Merge branch 'main' into vk/debug/nmap-both

Bumps [github.com/containerd/containerd](https://github.com/containerd/containerd) from 1.7.27 to 1.7.29.
- [Release notes](https://github.com/containerd/containerd/releases)
- [Changelog](https://github.com/containerd/containerd/blob/main/RELEASES.md)
- [Commits](https://github.com/containerd/containerd/compare/v1.7.27...v1.7.29)

---
updated-dependencies:
- dependency-name: github.com/containerd/containerd
  dependency-version: 1.7.29
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/docs-ack.yml

@@ -16,19 +16,29 @@ jobs:
     steps:
       - name: Read PR body
         id: body
+        shell: bash
         run: |
-          BODY=$(jq -r '.pull_request.body // ""' "$GITHUB_EVENT_PATH")
-          echo "body<<EOF" >> $GITHUB_OUTPUT
-          echo "$BODY" >> $GITHUB_OUTPUT
-          echo "EOF" >> $GITHUB_OUTPUT
+          set -euo pipefail
+          BODY_B64=$(jq -r '.pull_request.body // "" | @base64' "$GITHUB_EVENT_PATH")
+          {
+            echo "body_b64=$BODY_B64"
+          } >> "$GITHUB_OUTPUT"
 
       - name: Validate checkbox selection
         id: validate
+        shell: bash
+        env:
+          BODY_B64: ${{ steps.body.outputs.body_b64 }}
         run: |
-          body='${{ steps.body.outputs.body }}'
+          set -euo pipefail
+          if ! body="$(printf '%s' "$BODY_B64" | base64 -d)"; then
+            echo "::error::Failed to decode PR body from base64. Data may be corrupted or missing."
+            exit 1
+          fi
+
+          added_checked=$(printf '%s' "$body" | grep -Ei '^[[:space:]]*-\s*\[x\]\s*I added/updated documentation' | wc -l | tr -d '[:space:]' || true)
+          noneed_checked=$(printf '%s' "$body" | grep -Ei '^[[:space:]]*-\s*\[x\]\s*Documentation is \*\*not needed\*\*' | wc -l | tr -d '[:space:]' || true)
 
-          added_checked=$(printf "%s" "$body" | grep -E '^- \[x\] I added/updated documentation' -i | wc -l | tr -d ' ')
-          noneed_checked=$(printf "%s" "$body" | grep -E '^- \[x\] Documentation is \*\*not needed\*\*' -i | wc -l | tr -d ' ')
 
           if [ "$added_checked" -eq 1 ] && [ "$noneed_checked" -eq 1 ]; then
             echo "::error::Choose exactly one: either 'docs added' OR 'not needed'."
@@ -41,30 +51,35 @@ jobs:
           fi
 
           if [ "$added_checked" -eq 1 ]; then
-            echo "mode=added" >> $GITHUB_OUTPUT
+            echo "mode=added" >> "$GITHUB_OUTPUT"
           else
-            echo "mode=noneed" >> $GITHUB_OUTPUT
+            echo "mode=noneed" >> "$GITHUB_OUTPUT"
           fi
 
       - name: Extract docs PR URL (when 'docs added')
         if: steps.validate.outputs.mode == 'added'
         id: extract
+        shell: bash
+        env:
+          BODY_B64: ${{ steps.body.outputs.body_b64 }}
         run: |
-          body='${{ steps.body.outputs.body }}'
+          set -euo pipefail
+          body="$(printf '%s' "$BODY_B64" | base64 -d)"
 
           # Strictly require HTTPS and that it's a PR in netbirdio/docs
-          # Examples accepted:
-          #   https://github.com/netbirdio/docs/pull/1234
-          url=$(printf "%s" "$body" | grep -Eo 'https://github\.com/netbirdio/docs/pull/[0-9]+' | head -n1 || true)
+          # e.g., https://github.com/netbirdio/docs/pull/1234
+          url="$(printf '%s' "$body" | grep -Eo 'https://github\.com/netbirdio/docs/pull/[0-9]+' | head -n1 || true)"
 
-          if [ -z "$url" ]; then
+          if [ -z "${url:-}" ]; then
             echo "::error::You checked 'docs added' but didn't include a valid HTTPS PR link to netbirdio/docs (e.g., https://github.com/netbirdio/docs/pull/1234)."
             exit 1
           fi
 
-          pr_number=$(echo "$url" | sed -E 's#.*/pull/([0-9]+)$#\1#')
-          echo "url=$url" >> $GITHUB_OUTPUT
-          echo "pr_number=$pr_number" >> $GITHUB_OUTPUT
+          pr_number="$(printf '%s' "$url" | sed -E 's#.*/pull/([0-9]+)$#\1#')"
+          {
+            echo "url=$url"
+            echo "pr_number=$pr_number"
+          } >> "$GITHUB_OUTPUT"
 
       - name: Verify docs PR exists (and is open or merged)
         if: steps.validate.outputs.mode == 'added'

.github/workflows/golang-test-linux.yml

@@ -217,7 +217,7 @@ jobs:
           - arch: "386"
             raceFlag: ""
           - arch: "amd64"
-            raceFlag: ""
+            raceFlag: "-race"
     runs-on: ubuntu-22.04
     steps:
       - name: Install Go
@@ -382,6 +382,32 @@ jobs:
         store: [ 'sqlite', 'postgres' ]
     runs-on: ubuntu-22.04
     steps:
+      - name: Create Docker network
+        run: docker network create promnet
+
+      - name: Start Prometheus Pushgateway
+        run: docker run -d --name pushgateway --network promnet -p 9091:9091 prom/pushgateway
+
+      - name: Start Prometheus (for Pushgateway forwarding)
+        run: |
+          echo '
+          global:
+            scrape_interval: 15s
+          scrape_configs:
+            - job_name: "pushgateway"
+              static_configs:
+                - targets: ["pushgateway:9091"]
+          remote_write:
+            - url: ${{ secrets.GRAFANA_URL }}
+              basic_auth:
+                username: ${{ secrets.GRAFANA_USER }}
+                password: ${{ secrets.GRAFANA_API_KEY }}
+          ' > prometheus.yml
+
+          docker run -d --name prometheus --network promnet \
+            -v $PWD/prometheus.yml:/etc/prometheus/prometheus.yml \
+            -p 9090:9090 \
+            prom/prometheus
       - name: Install Go
         uses: actions/setup-go@v5
         with:
@@ -428,9 +454,10 @@ jobs:
           CGO_ENABLED=1 GOARCH=${{ matrix.arch }} \
           NETBIRD_STORE_ENGINE=${{ matrix.store }} \
           CI=true \
+          GIT_BRANCH=${{ github.ref_name }} \
           go test -tags devcert -run=^$ -bench=. \
-          -exec 'sudo --preserve-env=CI,NETBIRD_STORE_ENGINE' \
-          -timeout 20m ./management/... ./shared/management/...
+          -exec 'sudo --preserve-env=CI,NETBIRD_STORE_ENGINE,GIT_BRANCH,GITHUB_RUN_ID' \
+          -timeout 20m ./management/... ./shared/management/... $(go list ./management/... ./shared/management/... | grep -v -e /management/server/http)
 
   api_benchmark:
     name: "Management / Benchmark (API)"
@@ -521,7 +548,7 @@ jobs:
             -run=^$ \
             -bench=. \
             -exec 'sudo --preserve-env=CI,NETBIRD_STORE_ENGINE,GIT_BRANCH,GITHUB_RUN_ID' \
-            -timeout 20m ./management/... ./shared/management/...
+            -timeout 20m ./management/server/http/...
 
   api_integration_test:
     name: "Management / Integration"
@@ -571,4 +598,4 @@ jobs:
           CI=true \
           go test -tags=integration \
           -exec 'sudo --preserve-env=CI,NETBIRD_STORE_ENGINE' \
-          -timeout 20m ./management/... ./shared/management/...
+          -timeout 20m ./management/server/http/...

.github/workflows/golang-test-windows.yml

@@ -63,7 +63,7 @@ jobs:
       - run: PsExec64 -s -w ${{ github.workspace }} C:\hostedtoolcache\windows\go\${{ steps.go.outputs.go-version }}\x64\bin\go.exe env -w GOMODCACHE=${{ env.cache }}
       - run: PsExec64 -s -w ${{ github.workspace }} C:\hostedtoolcache\windows\go\${{ steps.go.outputs.go-version }}\x64\bin\go.exe env -w GOCACHE=${{ env.modcache }}
       - run: PsExec64 -s -w ${{ github.workspace }} C:\hostedtoolcache\windows\go\${{ steps.go.outputs.go-version }}\x64\bin\go.exe mod tidy
-      - run: echo "files=$(go list ./... | ForEach-Object { $_ } | Where-Object { $_ -notmatch '/management' })" >> $env:GITHUB_ENV
+      - run: echo "files=$(go list ./... | ForEach-Object { $_ } | Where-Object { $_ -notmatch '/management' } | Where-Object { $_ -notmatch '/relay' } | Where-Object { $_ -notmatch '/signal' })" >> $env:GITHUB_ENV
 
       - name: test
         run: PsExec64 -s -w ${{ github.workspace }} cmd.exe /c "C:\hostedtoolcache\windows\go\${{ steps.go.outputs.go-version }}\x64\bin\go.exe test -tags=devcert -timeout 10m -p 1 ${{ env.files }} > test-out.txt 2>&1"

.github/workflows/golangci-lint.yml

@@ -19,7 +19,7 @@ jobs:
       - name: codespell
         uses: codespell-project/actions-codespell@v2
         with:
-          ignore_words_list: erro,clienta,hastable,iif,groupd,testin,groupe
+          ignore_words_list: erro,clienta,hastable,iif,groupd,testin,groupe,cros
           skip: go.mod,go.sum
   golangci:
     strategy:

.github/workflows/release.yml

@@ -9,7 +9,7 @@ on:
   pull_request:
 
 env:
-  SIGN_PIPE_VER: "v0.0.22"
+  SIGN_PIPE_VER: "v0.0.23"
   GORELEASER_VER: "v2.3.2"
   PRODUCT_NAME: "NetBird"
   COPYRIGHT: "NetBird GmbH"

.github/workflows/wasm-build-validation.yml

@@ -0,0 +1,67 @@
+name: Wasm
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}-${{ github.head_ref || github.actor_id }}
+  cancel-in-progress: true
+
+jobs:
+  js_lint:
+    name: "JS / Lint"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - name: Install Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: "1.23.x"
+      - name: Install dependencies
+        run: sudo apt update && sudo apt install -y -q libgtk-3-dev libayatana-appindicator3-dev libgl1-mesa-dev xorg-dev libpcap-dev
+      - name: Install golangci-lint
+        uses: golangci/golangci-lint-action@d6238b002a20823d52840fda27e2d4891c5952dc
+        with:
+          version: latest
+          install-mode: binary
+          skip-cache: true
+          skip-pkg-cache: true
+          skip-build-cache: true
+      - name: Run golangci-lint for WASM
+        run: |
+          GOOS=js GOARCH=wasm golangci-lint run --timeout=12m --out-format colored-line-number ./client/...
+        continue-on-error: true
+
+  js_build:
+    name: "JS / Build"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - name: Install Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: "1.23.x"
+      - name: Build Wasm client
+        run: GOOS=js GOARCH=wasm go build -o netbird.wasm ./client/wasm/cmd
+        env:
+          CGO_ENABLED: 0
+      - name: Check Wasm build size
+        run: |
+          echo "Wasm build size:"
+          ls -lh netbird.wasm
+
+          SIZE=$(stat -c%s netbird.wasm)
+          SIZE_MB=$((SIZE / 1024 / 1024))
+
+          echo "Size: ${SIZE} bytes (${SIZE_MB} MB)"
+
+          if [ ${SIZE} -gt 52428800 ]; then
+            echo "Wasm binary size (${SIZE_MB}MB) exceeds 50MB limit!"
+            exit 1
+          fi
+

.goreleaser.yaml

@@ -2,6 +2,18 @@ version: 2
 
 project_name: netbird
 builds:
+  - id: netbird-wasm
+    dir: client/wasm/cmd
+    binary: netbird
+    env: [GOOS=js, GOARCH=wasm, CGO_ENABLED=0]
+    goos:
+      - js
+    goarch:
+      - wasm
+    ldflags:
+      - -s -w -X github.com/netbirdio/netbird/version.version={{.Version}} -X main.commit={{.Commit}} -X main.date={{.CommitDate}} -X main.builtBy=goreleaser
+    mod_timestamp: "{{ .CommitTimestamp }}"
+
   - id: netbird
     dir: client
     binary: netbird
@@ -115,6 +127,11 @@ archives:
   - builds:
       - netbird
       - netbird-static
+  - id: netbird-wasm
+    builds:
+      - netbird-wasm
+    name_template: "{{ .ProjectName }}_{{ .Version }}"
+    format: binary
 
 nfpms:
   - maintainer: Netbird <dev@netbird.io>

README.md

@@ -1,3 +1,4 @@
+
 <div align="center">
 <br/>
   <br/>
@@ -52,7 +53,7 @@
 
 ### Open Source Network Security in a Single Platform
 
-<img width="1188" alt="centralized-network-management 1" src="https://github.com/user-attachments/assets/c28cc8e4-15d2-4d2f-bb97-a6433db39d56" />
+https://github.com/user-attachments/assets/10cec749-bb56-4ab3-97af-4e38850108d2
 
 ### NetBird on Lawrence Systems (Video)
 [![Watch the video](https://img.youtube.com/vi/Kwrff6h0rEw/0.jpg)](https://www.youtube.com/watch?v=Kwrff6h0rEw)

client/Dockerfile

@@ -4,7 +4,7 @@
 #   sudo podman build -t localhost/netbird:latest -f client/Dockerfile --ignorefile .dockerignore-client .
 #   sudo podman run --rm -it --cap-add={BPF,NET_ADMIN,NET_RAW} localhost/netbird:latest
 
-FROM alpine:3.22.0
+FROM alpine:3.22.2
 # iproute2: busybox doesn't display ip rules properly
 RUN apk add --no-cache \
     bash \
@@ -18,7 +18,7 @@ ENV \
     NB_LOG_FILE="console,/var/log/netbird/client.log" \
     NB_DAEMON_ADDR="unix:///var/run/netbird.sock" \
     NB_ENTRYPOINT_SERVICE_TIMEOUT="5" \
-    NB_ENTRYPOINT_LOGIN_TIMEOUT="1"
+    NB_ENTRYPOINT_LOGIN_TIMEOUT="5"
 
 ENTRYPOINT [ "/usr/local/bin/netbird-entrypoint.sh" ]
 

client/android/client.go

@@ -4,6 +4,7 @@ package android
 
 import (
 	"context"
+	"os"
 	"slices"
 	"sync"
 
@@ -18,7 +19,7 @@ import (
 	"github.com/netbirdio/netbird/client/internal/stdnet"
 	"github.com/netbirdio/netbird/client/system"
 	"github.com/netbirdio/netbird/formatter"
-	"github.com/netbirdio/netbird/util/net"
+	"github.com/netbirdio/netbird/client/net"
 )
 
 // ConnectionListener export internal Listener for mobile
@@ -83,7 +84,8 @@ func NewClient(cfgFile string, androidSDKVersion int, deviceName string, uiVersi
 }
 
 // Run start the internal client. It is a blocker function
-func (c *Client) Run(urlOpener URLOpener, dns *DNSList, dnsReadyListener DnsReadyListener) error {
+func (c *Client) Run(urlOpener URLOpener, dns *DNSList, dnsReadyListener DnsReadyListener, envList *EnvList) error {
+	exportEnvList(envList)
 	cfg, err := profilemanager.UpdateOrCreateConfig(profilemanager.ConfigInput{
 		ConfigPath: c.cfgFile,
 	})
@@ -118,7 +120,8 @@ func (c *Client) Run(urlOpener URLOpener, dns *DNSList, dnsReadyListener DnsRead
 
 // RunWithoutLogin we apply this type of run function when the backed has been started without UI (i.e. after reboot).
 // In this case make no sense handle registration steps.
-func (c *Client) RunWithoutLogin(dns *DNSList, dnsReadyListener DnsReadyListener) error {
+func (c *Client) RunWithoutLogin(dns *DNSList, dnsReadyListener DnsReadyListener, envList *EnvList) error {
+	exportEnvList(envList)
 	cfg, err := profilemanager.UpdateOrCreateConfig(profilemanager.ConfigInput{
 		ConfigPath: c.cfgFile,
 	})
@@ -249,3 +252,14 @@ func (c *Client) SetConnectionListener(listener ConnectionListener) {
 func (c *Client) RemoveConnectionListener() {
 	c.recorder.RemoveConnectionListener()
 }
+
+func exportEnvList(list *EnvList) {
+	if list == nil {
+		return
+	}
+	for k, v := range list.AllItems() {
+		if err := os.Setenv(k, v); err != nil {
+			log.Errorf("could not set env variable %s: %v", k, err)
+		}
+	}
+}

client/android/env_list.go

@@ -0,0 +1,32 @@
+package android
+
+import "github.com/netbirdio/netbird/client/internal/peer"
+
+var (
+	// EnvKeyNBForceRelay Exported for Android java client
+	EnvKeyNBForceRelay = peer.EnvKeyNBForceRelay
+)
+
+// EnvList wraps a Go map for export to Java
+type EnvList struct {
+	data map[string]string
+}
+
+// NewEnvList creates a new EnvList
+func NewEnvList() *EnvList {
+	return &EnvList{data: make(map[string]string)}
+}
+
+// Put adds a key-value pair
+func (el *EnvList) Put(key, value string) {
+	el.data[key] = value
+}
+
+// Get retrieves a value by key
+func (el *EnvList) Get(key string) string {
+	return el.data[key]
+}
+
+func (el *EnvList) AllItems() map[string]string {
+	return el.data
+}

client/android/login.go

@@ -33,6 +33,7 @@ type ErrListener interface {
 // the backend want to show an url for the user
 type URLOpener interface {
 	Open(string)
+	OnLoginSuccess()
 }
 
 // Auth can register or login new client
@@ -181,6 +182,11 @@ func (a *Auth) login(urlOpener URLOpener) error {
 
 	err = a.withBackOff(a.ctx, func() error {
 		err := internal.Login(a.ctx, a.config, "", jwtToken)
+
+		if err == nil {
+			go urlOpener.OnLoginSuccess()
+		}
+
 		if s, ok := gstatus.FromError(err); ok && (s.Code() == codes.InvalidArgument || s.Code() == codes.PermissionDenied) {
 			return nil
 		}
@@ -194,7 +200,7 @@ func (a *Auth) login(urlOpener URLOpener) error {
 }
 
 func (a *Auth) foregroundGetTokenInfo(urlOpener URLOpener) (*auth.TokenInfo, error) {
-	oAuthFlow, err := auth.NewOAuthFlow(a.ctx, a.config, false)
+	oAuthFlow, err := auth.NewOAuthFlow(a.ctx, a.config, false, "")
 	if err != nil {
 		return nil, err
 	}

client/cmd/debug.go

@@ -168,7 +168,7 @@ func runForDuration(cmd *cobra.Command, args []string) error {
 
 	client := proto.NewDaemonServiceClient(conn)
 
-	stat, err := client.Status(cmd.Context(), &proto.StatusRequest{})
+	stat, err := client.Status(cmd.Context(), &proto.StatusRequest{ShouldRunProbes: true})
 	if err != nil {
 		return fmt.Errorf("failed to get status: %v", status.Convert(err).Message())
 	}
@@ -303,12 +303,18 @@ func setSyncResponsePersistence(cmd *cobra.Command, args []string) error {
 
 func getStatusOutput(cmd *cobra.Command, anon bool) string {
 	var statusOutputString string
-	statusResp, err := getStatus(cmd.Context())
+	statusResp, err := getStatus(cmd.Context(), true)
 	if err != nil {
 		cmd.PrintErrf("Failed to get status: %v\n", err)
 	} else {
+		pm := profilemanager.NewProfileManager()
+		var profName string
+		if activeProf, err := pm.GetActiveProfile(); err == nil {
+			profName = activeProf.Name
+		}
+
 		statusOutputString = nbstatus.ParseToFullDetailSummary(
-			nbstatus.ConvertToStatusOutputOverview(statusResp, anon, "", nil, nil, nil, "", ""),
+			nbstatus.ConvertToStatusOutputOverview(statusResp, anon, "", nil, nil, nil, "", profName),
 		)
 	}
 	return statusOutputString

client/cmd/debug_js.go

@@ -0,0 +1,8 @@
+package cmd
+
+import "context"
+
+// SetupDebugHandler is a no-op for WASM
+func SetupDebugHandler(context.Context, interface{}, interface{}, interface{}, string) {
+	// Debug handler not needed for WASM
+}

client/cmd/down.go

@@ -27,7 +27,7 @@ var downCmd = &cobra.Command{
 			return err
 		}
 
-		ctx, cancel := context.WithTimeout(context.Background(), time.Second*7)
+		ctx, cancel := context.WithTimeout(context.Background(), time.Second*20)
 		defer cancel()
 
 		conn, err := DialClientGRPCServer(ctx, daemonAddr)

client/cmd/login.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"os/exec"
 	"os/user"
 	"runtime"
 	"strings"
@@ -105,6 +106,13 @@ func doDaemonLogin(ctx context.Context, cmd *cobra.Command, providedSetupKey str
 		Username:            &username,
 	}
 
+	profileState, err := pm.GetProfileState(activeProf.Name)
+	if err != nil {
+		log.Debugf("failed to get profile state for login hint: %v", err)
+	} else if profileState.Email != "" {
+		loginRequest.Hint = &profileState.Email
+	}
+
 	if rootCmd.PersistentFlags().Changed(preSharedKeyFlag) {
 		loginRequest.OptionalPreSharedKey = &preSharedKey
 	}
@@ -227,7 +235,7 @@ func doForegroundLogin(ctx context.Context, cmd *cobra.Command, setupKey string,
 	}
 
 	// update host's static platform and system information
-	system.UpdateStaticInfo()
+	system.UpdateStaticInfoAsync()
 
 	configFilePath, err := activeProf.FilePath()
 	if err != nil {
@@ -240,7 +248,7 @@ func doForegroundLogin(ctx context.Context, cmd *cobra.Command, setupKey string,
 		return fmt.Errorf("read config file %s: %v", configFilePath, err)
 	}
 
-	err = foregroundLogin(ctx, cmd, config, setupKey)
+	err = foregroundLogin(ctx, cmd, config, setupKey, activeProf.Name)
 	if err != nil {
 		return fmt.Errorf("foreground login failed: %v", err)
 	}
@@ -268,7 +276,7 @@ func handleSSOLogin(ctx context.Context, cmd *cobra.Command, loginResp *proto.Lo
 	return nil
 }
 
-func foregroundLogin(ctx context.Context, cmd *cobra.Command, config *profilemanager.Config, setupKey string) error {
+func foregroundLogin(ctx context.Context, cmd *cobra.Command, config *profilemanager.Config, setupKey, profileName string) error {
 	needsLogin := false
 
 	err := WithBackOff(func() error {
@@ -285,7 +293,7 @@ func foregroundLogin(ctx context.Context, cmd *cobra.Command, config *profileman
 
 	jwtToken := ""
 	if setupKey == "" && needsLogin {
-		tokenInfo, err := foregroundGetTokenInfo(ctx, cmd, config)
+		tokenInfo, err := foregroundGetTokenInfo(ctx, cmd, config, profileName)
 		if err != nil {
 			return fmt.Errorf("interactive sso login failed: %v", err)
 		}
@@ -314,8 +322,17 @@ func foregroundLogin(ctx context.Context, cmd *cobra.Command, config *profileman
 	return nil
 }
 
-func foregroundGetTokenInfo(ctx context.Context, cmd *cobra.Command, config *profilemanager.Config) (*auth.TokenInfo, error) {
-	oAuthFlow, err := auth.NewOAuthFlow(ctx, config, isUnixRunningDesktop())
+func foregroundGetTokenInfo(ctx context.Context, cmd *cobra.Command, config *profilemanager.Config, profileName string) (*auth.TokenInfo, error) {
+	hint := ""
+	pm := profilemanager.NewProfileManager()
+	profileState, err := pm.GetProfileState(profileName)
+	if err != nil {
+		log.Debugf("failed to get profile state for login hint: %v", err)
+	} else if profileState.Email != "" {
+		hint = profileState.Email
+	}
+
+	oAuthFlow, err := auth.NewOAuthFlow(ctx, config, isUnixRunningDesktop(), hint)
 	if err != nil {
 		return nil, err
 	}
@@ -356,13 +373,21 @@ func openURL(cmd *cobra.Command, verificationURIComplete, userCode string, noBro
 	cmd.Println("")
 
 	if !noBrowser {
-		if err := open.Run(verificationURIComplete); err != nil {
+		if err := openBrowser(verificationURIComplete); err != nil {
 			cmd.Println("\nAlternatively, you may want to use a setup key, see:\n\n" +
 				"https://docs.netbird.io/how-to/register-machines-using-setup-keys")
 		}
 	}
 }
 
+// openBrowser opens the URL in a browser, respecting the BROWSER environment variable.
+func openBrowser(url string) error {
+	if browser := os.Getenv("BROWSER"); browser != "" {
+		return exec.Command(browser, url).Start()
+	}
+	return open.Run(url)
+}
+
 // isUnixRunningDesktop checks if a Linux OS is running desktop environment
 func isUnixRunningDesktop() bool {
 	if runtime.GOOS != "linux" && runtime.GOOS != "freebsd" {

client/cmd/root.go

@@ -39,6 +39,7 @@ const (
 	extraIFaceBlackListFlag  = "extra-iface-blacklist"
 	dnsRouteIntervalFlag     = "dns-router-interval"
 	enableLazyConnectionFlag = "enable-lazy-connection"
+	mtuFlag                  = "mtu"
 )
 
 var (
@@ -72,6 +73,7 @@ var (
 	anonymizeFlag           bool
 	dnsRouteInterval        time.Duration
 	lazyConnEnabled         bool
+	mtu                     uint16
 	profilesDisabled        bool
 	updateSettingsDisabled  bool
 
@@ -229,7 +231,7 @@ func FlagNameToEnvVar(cmdFlag string, prefix string) string {
 
 // DialClientGRPCServer returns client connection to the daemon server.
 func DialClientGRPCServer(ctx context.Context, addr string) (*grpc.ClientConn, error) {
-	ctx, cancel := context.WithTimeout(ctx, time.Second*3)
+	ctx, cancel := context.WithTimeout(ctx, time.Second*10)
 	defer cancel()
 
 	return grpc.DialContext(

client/cmd/root_test.go

@@ -54,6 +54,7 @@ func TestSetFlagsFromEnvVars(t *testing.T) {
 	cmd.PersistentFlags().StringVar(&interfaceName, interfaceNameFlag, iface.WgInterfaceDefault, "WireGuard interface name")
 	cmd.PersistentFlags().BoolVar(&rosenpassEnabled, enableRosenpassFlag, false, "Enable Rosenpass feature Rosenpass.")
 	cmd.PersistentFlags().Uint16Var(&wireguardPort, wireguardPortFlag, iface.DefaultWgPort, "WireGuard interface listening port")
+	cmd.PersistentFlags().Uint16Var(&mtu, mtuFlag, iface.DefaultMTU, "Set MTU (Maximum Transmission Unit) for the WireGuard interface")
 
 	t.Setenv("NB_EXTERNAL_IP_MAP", "abc,dec")
 	t.Setenv("NB_INTERFACE_NAME", "test-name")

client/cmd/service_controller.go

@@ -27,7 +27,7 @@ func (p *program) Start(svc service.Service) error {
 	log.Info("starting NetBird service") //nolint
 
 	// Collect static system and platform information
-	system.UpdateStaticInfo()
+	system.UpdateStaticInfoAsync()
 
 	// in any case, even if configuration does not exists we run daemon to serve CLI gRPC API.
 	p.serv = grpc.NewServer()

client/cmd/service_installer.go

@@ -10,6 +10,8 @@ import (
 	"path/filepath"
 	"runtime"
 
+	log "github.com/sirupsen/logrus"
+
 	"github.com/kardianos/service"
 	"github.com/spf13/cobra"
 
@@ -81,6 +83,10 @@ func configurePlatformSpecificSettings(svcConfig *service.Config) error {
 				svcConfig.Option["LogDirectory"] = dir
 			}
 		}
+
+		if err := configureSystemdNetworkd(); err != nil {
+			log.Warnf("failed to configure systemd-networkd: %v", err)
+		}
 	}
 
 	if runtime.GOOS == "windows" {
@@ -160,6 +166,12 @@ var uninstallCmd = &cobra.Command{
 			return fmt.Errorf("uninstall service: %w", err)
 		}
 
+		if runtime.GOOS == "linux" {
+			if err := cleanupSystemdNetworkd(); err != nil {
+				log.Warnf("failed to cleanup systemd-networkd configuration: %v", err)
+			}
+		}
+
 		cmd.Println("NetBird service has been uninstalled")
 		return nil
 	},
@@ -245,3 +257,50 @@ func isServiceRunning() (bool, error) {
 
 	return status == service.StatusRunning, nil
 }
+
+const (
+	networkdConf        = "/etc/systemd/networkd.conf"
+	networkdConfDir     = "/etc/systemd/networkd.conf.d"
+	networkdConfFile    = "/etc/systemd/networkd.conf.d/99-netbird.conf"
+	networkdConfContent = `# Created by NetBird to prevent systemd-networkd from removing
+# routes and policy rules managed by NetBird.
+
+[Network]
+ManageForeignRoutes=no
+ManageForeignRoutingPolicyRules=no
+`
+)
+
+// configureSystemdNetworkd creates a drop-in configuration file to prevent
+// systemd-networkd from removing NetBird's routes and policy rules.
+func configureSystemdNetworkd() error {
+	if _, err := os.Stat(networkdConf); os.IsNotExist(err) {
+		log.Debug("systemd-networkd not in use, skipping configuration")
+		return nil
+	}
+
+	// nolint:gosec // standard networkd permissions
+	if err := os.MkdirAll(networkdConfDir, 0755); err != nil {
+		return fmt.Errorf("create networkd.conf.d directory: %w", err)
+	}
+
+	// nolint:gosec // standard networkd permissions
+	if err := os.WriteFile(networkdConfFile, []byte(networkdConfContent), 0644); err != nil {
+		return fmt.Errorf("write networkd configuration: %w", err)
+	}
+
+	return nil
+}
+
+// cleanupSystemdNetworkd removes the NetBird systemd-networkd configuration file.
+func cleanupSystemdNetworkd() error {
+	if _, err := os.Stat(networkdConfFile); os.IsNotExist(err) {
+		return nil
+	}
+
+	if err := os.Remove(networkdConfFile); err != nil {
+		return fmt.Errorf("remove networkd configuration: %w", err)
+	}
+
+	return nil
+}

client/cmd/status.go

@@ -68,7 +68,7 @@ func statusFunc(cmd *cobra.Command, args []string) error {
 
 	ctx := internal.CtxInitState(cmd.Context())
 
-	resp, err := getStatus(ctx)
+	resp, err := getStatus(ctx, false)
 	if err != nil {
 		return err
 	}
@@ -121,7 +121,7 @@ func statusFunc(cmd *cobra.Command, args []string) error {
 	return nil
 }
 
-func getStatus(ctx context.Context) (*proto.StatusResponse, error) {
+func getStatus(ctx context.Context, shouldRunProbes bool) (*proto.StatusResponse, error) {
 	conn, err := DialClientGRPCServer(ctx, daemonAddr)
 	if err != nil {
 		return nil, fmt.Errorf("failed to connect to daemon error: %v\n"+
@@ -130,7 +130,7 @@ func getStatus(ctx context.Context) (*proto.StatusResponse, error) {
 	}
 	defer conn.Close()
 
-	resp, err := proto.NewDaemonServiceClient(conn).Status(ctx, &proto.StatusRequest{GetFullPeerStatus: true, ShouldRunProbes: true})
+	resp, err := proto.NewDaemonServiceClient(conn).Status(ctx, &proto.StatusRequest{GetFullPeerStatus: true, ShouldRunProbes: shouldRunProbes})
 	if err != nil {
 		return nil, fmt.Errorf("status failed: %v", status.Convert(err).Message())
 	}

client/cmd/testutil_test.go

@@ -9,29 +9,28 @@ import (
 	"github.com/golang/mock/gomock"
 	"github.com/stretchr/testify/require"
 	"go.opentelemetry.io/otel"
-
-	"github.com/netbirdio/netbird/management/internals/server/config"
-	"github.com/netbirdio/netbird/management/server/activity"
-	"github.com/netbirdio/netbird/management/server/groups"
-	"github.com/netbirdio/netbird/management/server/integrations/port_forwarding"
-	"github.com/netbirdio/netbird/management/server/permissions"
-	"github.com/netbirdio/netbird/management/server/settings"
-	"github.com/netbirdio/netbird/management/server/store"
-	"github.com/netbirdio/netbird/management/server/telemetry"
-	"github.com/netbirdio/netbird/management/server/types"
-
-	"github.com/netbirdio/netbird/util"
-
 	"google.golang.org/grpc"
 
 	"github.com/netbirdio/management-integrations/integrations"
 
 	clientProto "github.com/netbirdio/netbird/client/proto"
 	client "github.com/netbirdio/netbird/client/server"
+	"github.com/netbirdio/netbird/management/internals/server/config"
 	mgmt "github.com/netbirdio/netbird/management/server"
+	"github.com/netbirdio/netbird/management/server/activity"
+	"github.com/netbirdio/netbird/management/server/groups"
+	"github.com/netbirdio/netbird/management/server/integrations/port_forwarding"
+	"github.com/netbirdio/netbird/management/server/peers"
+	"github.com/netbirdio/netbird/management/server/peers/ephemeral/manager"
+	"github.com/netbirdio/netbird/management/server/permissions"
+	"github.com/netbirdio/netbird/management/server/settings"
+	"github.com/netbirdio/netbird/management/server/store"
+	"github.com/netbirdio/netbird/management/server/telemetry"
+	"github.com/netbirdio/netbird/management/server/types"
 	mgmtProto "github.com/netbirdio/netbird/shared/management/proto"
 	sigProto "github.com/netbirdio/netbird/shared/signal/proto"
 	sig "github.com/netbirdio/netbird/signal/server"
+	"github.com/netbirdio/netbird/util"
 )
 
 func startTestingServices(t *testing.T) string {
@@ -86,20 +85,24 @@ func startManagement(t *testing.T, config *config.Config, testFile string) (*grp
 	t.Cleanup(cleanUp)
 
 	peersUpdateManager := mgmt.NewPeersUpdateManager(nil)
-	jobManager := mgmt.NewJobManager(nil, store)
 	eventStore := &activity.InMemoryEventStore{}
 	if err != nil {
 		return nil, nil
 	}
-	iv, _ := integrations.NewIntegratedValidator(context.Background(), eventStore)
 
-	metrics, err := telemetry.NewDefaultAppMetrics(context.Background())
-	require.NoError(t, err)
 	ctrl := gomock.NewController(t)
 	t.Cleanup(ctrl.Finish)
 
-	settingsMockManager := settings.NewMockManager(ctrl)
 	permissionsManagerMock := permissions.NewMockManager(ctrl)
+	peersmanager := peers.NewManager(store, permissionsManagerMock)
+	settingsManagerMock := settings.NewMockManager(ctrl)
+
+	iv, _ := integrations.NewIntegratedValidator(context.Background(), peersmanager, settingsManagerMock, eventStore)
+
+	metrics, err := telemetry.NewDefaultAppMetrics(context.Background())
+	require.NoError(t, err)
+
+	settingsMockManager := settings.NewMockManager(ctrl)
 	groupsManager := groups.NewManagerMock()
 
 	settingsMockManager.EXPECT().
@@ -107,13 +110,13 @@ func startManagement(t *testing.T, config *config.Config, testFile string) (*grp
 		Return(&types.Settings{}, nil).
 		AnyTimes()
 
-	accountManager, err := mgmt.BuildManager(context.Background(), store, peersUpdateManager, jobManager, nil, "", "netbird.selfhosted", eventStore, nil, false, iv, metrics, port_forwarding.NewControllerMock(), settingsMockManager, permissionsManagerMock, false)
+	accountManager, err := mgmt.BuildManager(context.Background(), store, peersUpdateManager, nil, "", "netbird.selfhosted", eventStore, nil, false, iv, metrics, port_forwarding.NewControllerMock(), settingsMockManager, permissionsManagerMock, false)
 	if err != nil {
 		t.Fatal(err)
 	}
 
 	secretsManager := mgmt.NewTimeBasedAuthSecretsManager(peersUpdateManager, config.TURNConfig, config.Relay, settingsMockManager, groupsManager)
-	mgmtServer, err := mgmt.NewServer(context.Background(), config, accountManager, settingsMockManager, peersUpdateManager, jobManager, secretsManager, nil, nil, nil, &mgmt.MockIntegratedValidator{})
+	mgmtServer, err := mgmt.NewServer(context.Background(), config, accountManager, settingsMockManager, peersUpdateManager, secretsManager, nil, &manager.EphemeralManager{}, nil, &mgmt.MockIntegratedValidator{})
 	if err != nil {
 		t.Fatal(err)
 	}

client/cmd/up.go

@@ -63,6 +63,7 @@ func init() {
 	upCmd.PersistentFlags().BoolVarP(&foregroundMode, "foreground-mode", "F", false, "start service in foreground")
 	upCmd.PersistentFlags().StringVar(&interfaceName, interfaceNameFlag, iface.WgInterfaceDefault, "WireGuard interface name")
 	upCmd.PersistentFlags().Uint16Var(&wireguardPort, wireguardPortFlag, iface.DefaultWgPort, "WireGuard interface listening port")
+	upCmd.PersistentFlags().Uint16Var(&mtu, mtuFlag, iface.DefaultMTU, "Set MTU (Maximum Transmission Unit) for the WireGuard interface")
 	upCmd.PersistentFlags().BoolVarP(&networkMonitor, networkMonitorFlag, "N", networkMonitor,
 		`Manage network monitoring. Defaults to true on Windows and macOS, false on Linux and FreeBSD. `+
 			`E.g. --network-monitor=false to disable or --network-monitor=true to enable.`,
@@ -184,7 +185,7 @@ func runInForegroundMode(ctx context.Context, cmd *cobra.Command, activeProf *pr
 
 	_, _ = profilemanager.UpdateOldManagementURL(ctx, config, configFilePath)
 
-	err = foregroundLogin(ctx, cmd, config, providedSetupKey)
+	err = foregroundLogin(ctx, cmd, config, providedSetupKey, activeProf.Name)
 	if err != nil {
 		return fmt.Errorf("foreground login failed: %v", err)
 	}
@@ -229,7 +230,9 @@ func runInDaemonMode(ctx context.Context, cmd *cobra.Command, pm *profilemanager
 
 	client := proto.NewDaemonServiceClient(conn)
 
-	status, err := client.Status(ctx, &proto.StatusRequest{})
+	status, err := client.Status(ctx, &proto.StatusRequest{
+		WaitForReady: func() *bool { b := true; return &b }(),
+	})
 	if err != nil {
 		return fmt.Errorf("unable to get daemon status: %v", err)
 	}
@@ -283,6 +286,13 @@ func doDaemonUp(ctx context.Context, cmd *cobra.Command, client proto.DaemonServ
 	loginRequest.ProfileName = &activeProf.Name
 	loginRequest.Username = &username
 
+	profileState, err := pm.GetProfileState(activeProf.Name)
+	if err != nil {
+		log.Debugf("failed to get profile state for login hint: %v", err)
+	} else if profileState.Email != "" {
+		loginRequest.Hint = &profileState.Email
+	}
+
 	var loginErr error
 	var loginResp *proto.LoginResponse
 
@@ -357,6 +367,11 @@ func setupSetConfigReq(customDNSAddressConverted []byte, cmd *cobra.Command, pro
 		req.WireguardPort = &p
 	}
 
+	if cmd.Flag(mtuFlag).Changed {
+		m := int64(mtu)
+		req.Mtu = &m
+	}
+
 	if cmd.Flag(networkMonitorFlag).Changed {
 		req.NetworkMonitor = &networkMonitor
 	}
@@ -436,6 +451,13 @@ func setupConfig(customDNSAddressConverted []byte, cmd *cobra.Command, configFil
 		ic.WireguardPort = &p
 	}
 
+	if cmd.Flag(mtuFlag).Changed {
+		if err := iface.ValidateMTU(mtu); err != nil {
+			return nil, err
+		}
+		ic.MTU = &mtu
+	}
+
 	if cmd.Flag(networkMonitorFlag).Changed {
 		ic.NetworkMonitor = &networkMonitor
 	}
@@ -533,6 +555,14 @@ func setupLoginRequest(providedSetupKey string, customDNSAddressConverted []byte
 		loginRequest.WireguardPort = &wp
 	}
 
+	if cmd.Flag(mtuFlag).Changed {
+		if err := iface.ValidateMTU(mtu); err != nil {
+			return nil, err
+		}
+		m := int64(mtu)
+		loginRequest.Mtu = &m
+	}
+
 	if cmd.Flag(networkMonitorFlag).Changed {
 		loginRequest.NetworkMonitor = &networkMonitor
 	}

client/embed/embed.go

@@ -23,23 +23,29 @@ import (
 
 var ErrClientAlreadyStarted = errors.New("client already started")
 var ErrClientNotStarted = errors.New("client not started")
+var ErrConfigNotInitialized = errors.New("config not initialized")
 
-// Client manages a netbird embedded client instance
+// Client manages a netbird embedded client instance.
 type Client struct {
 	deviceName string
 	config     *profilemanager.Config
 	mu         sync.Mutex
 	cancel     context.CancelFunc
 	setupKey   string
+	jwtToken   string
 	connect    *internal.ConnectClient
 }
 
-// Options configures a new Client
+// Options configures a new Client.
 type Options struct {
 	// DeviceName is this peer's name in the network
 	DeviceName string
 	// SetupKey is used for authentication
 	SetupKey string
+	// JWTToken is used for JWT-based authentication
+	JWTToken string
+	// PrivateKey is used for direct private key authentication
+	PrivateKey string
 	// ManagementURL overrides the default management server URL
 	ManagementURL string
 	// PreSharedKey is the pre-shared key for the WireGuard interface
@@ -58,8 +64,35 @@ type Options struct {
 	DisableClientRoutes bool
 }
 
-// New creates a new netbird embedded client
+// validateCredentials checks that exactly one credential type is provided
+func (opts *Options) validateCredentials() error {
+	credentialsProvided := 0
+	if opts.SetupKey != "" {
+		credentialsProvided++
+	}
+	if opts.JWTToken != "" {
+		credentialsProvided++
+	}
+	if opts.PrivateKey != "" {
+		credentialsProvided++
+	}
+
+	if credentialsProvided == 0 {
+		return fmt.Errorf("one of SetupKey, JWTToken, or PrivateKey must be provided")
+	}
+	if credentialsProvided > 1 {
+		return fmt.Errorf("only one of SetupKey, JWTToken, or PrivateKey can be specified")
+	}
+
+	return nil
+}
+
+// New creates a new netbird embedded client.
 func New(opts Options) (*Client, error) {
+	if err := opts.validateCredentials(); err != nil {
+		return nil, err
+	}
+
 	if opts.LogOutput != nil {
 		logrus.SetOutput(opts.LogOutput)
 	}
@@ -107,9 +140,14 @@ func New(opts Options) (*Client, error) {
 		return nil, fmt.Errorf("create config: %w", err)
 	}
 
+	if opts.PrivateKey != "" {
+		config.PrivateKey = opts.PrivateKey
+	}
+
 	return &Client{
 		deviceName: opts.DeviceName,
 		setupKey:   opts.SetupKey,
+		jwtToken:   opts.JWTToken,
 		config:     config,
 	}, nil
 }
@@ -126,7 +164,7 @@ func (c *Client) Start(startCtx context.Context) error {
 	ctx := internal.CtxInitState(context.Background())
 	// nolint:staticcheck
 	ctx = context.WithValue(ctx, system.DeviceNameCtxKey, c.deviceName)
-	if err := internal.Login(ctx, c.config, c.setupKey, ""); err != nil {
+	if err := internal.Login(ctx, c.config, c.setupKey, c.jwtToken); err != nil {
 		return fmt.Errorf("login: %w", err)
 	}
 
@@ -135,7 +173,7 @@ func (c *Client) Start(startCtx context.Context) error {
 
 	// either startup error (permanent backoff err) or nil err (successful engine up)
 	// TODO: make after-startup backoff err available
-	run := make(chan struct{}, 1)
+	run := make(chan struct{})
 	clientErr := make(chan error, 1)
 	go func() {
 		if err := client.Run(run); err != nil {
@@ -187,6 +225,16 @@ func (c *Client) Stop(ctx context.Context) error {
 	}
 }
 
+// GetConfig returns a copy of the internal client config.
+func (c *Client) GetConfig() (profilemanager.Config, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.config == nil {
+		return profilemanager.Config{}, ErrConfigNotInitialized
+	}
+	return *c.config, nil
+}
+
 // Dial dials a network address in the netbird network.
 // Not applicable if the userspace networking mode is disabled.
 func (c *Client) Dial(ctx context.Context, network, address string) (net.Conn, error) {
@@ -211,7 +259,7 @@ func (c *Client) Dial(ctx context.Context, network, address string) (net.Conn, e
 	return nsnet.DialContext(ctx, network, address)
 }
 
-// ListenTCP listens on the given address in the netbird network
+// ListenTCP listens on the given address in the netbird network.
 // Not applicable if the userspace networking mode is disabled.
 func (c *Client) ListenTCP(address string) (net.Listener, error) {
 	nsnet, addr, err := c.getNet()
@@ -232,7 +280,7 @@ func (c *Client) ListenTCP(address string) (net.Listener, error) {
 	return nsnet.ListenTCP(tcpAddr)
 }
 
-// ListenUDP listens on the given address in the netbird network
+// ListenUDP listens on the given address in the netbird network.
 // Not applicable if the userspace networking mode is disabled.
 func (c *Client) ListenUDP(address string) (net.PacketConn, error) {
 	nsnet, addr, err := c.getNet()

client/firewall/create.go

@@ -15,13 +15,13 @@ import (
 )
 
 // NewFirewall creates a firewall manager instance
-func NewFirewall(iface IFaceMapper, _ *statemanager.Manager, flowLogger nftypes.FlowLogger, disableServerRoutes bool) (firewall.Manager, error) {
+func NewFirewall(iface IFaceMapper, _ *statemanager.Manager, flowLogger nftypes.FlowLogger, disableServerRoutes bool, mtu uint16) (firewall.Manager, error) {
 	if !iface.IsUserspaceBind() {
 		return nil, fmt.Errorf("not implemented for this OS: %s", runtime.GOOS)
 	}
 
 	// use userspace packet filtering firewall
-	fm, err := uspfilter.Create(iface, disableServerRoutes, flowLogger)
+	fm, err := uspfilter.Create(iface, disableServerRoutes, flowLogger, mtu)
 	if err != nil {
 		return nil, err
 	}

client/firewall/create_linux.go

@@ -34,12 +34,12 @@ const SKIP_NFTABLES_ENV = "NB_SKIP_NFTABLES_CHECK"
 // FWType is the type for the firewall type
 type FWType int
 
-func NewFirewall(iface IFaceMapper, stateManager *statemanager.Manager, flowLogger nftypes.FlowLogger, disableServerRoutes bool) (firewall.Manager, error) {
+func NewFirewall(iface IFaceMapper, stateManager *statemanager.Manager, flowLogger nftypes.FlowLogger, disableServerRoutes bool, mtu uint16) (firewall.Manager, error) {
 	// on the linux system we try to user nftables or iptables
 	// in any case, because we need to allow netbird interface traffic
 	// so we use AllowNetbird traffic from these firewall managers
 	// for the userspace packet filtering firewall
-	fm, err := createNativeFirewall(iface, stateManager, disableServerRoutes)
+	fm, err := createNativeFirewall(iface, stateManager, disableServerRoutes, mtu)
 
 	if !iface.IsUserspaceBind() {
 		return fm, err
@@ -48,11 +48,11 @@ func NewFirewall(iface IFaceMapper, stateManager *statemanager.Manager, flowLogg
 	if err != nil {
 		log.Warnf("failed to create native firewall: %v. Proceeding with userspace", err)
 	}
-	return createUserspaceFirewall(iface, fm, disableServerRoutes, flowLogger)
+	return createUserspaceFirewall(iface, fm, disableServerRoutes, flowLogger, mtu)
 }
 
-func createNativeFirewall(iface IFaceMapper, stateManager *statemanager.Manager, routes bool) (firewall.Manager, error) {
-	fm, err := createFW(iface)
+func createNativeFirewall(iface IFaceMapper, stateManager *statemanager.Manager, routes bool, mtu uint16) (firewall.Manager, error) {
+	fm, err := createFW(iface, mtu)
 	if err != nil {
 		return nil, fmt.Errorf("create firewall: %s", err)
 	}
@@ -64,26 +64,26 @@ func createNativeFirewall(iface IFaceMapper, stateManager *statemanager.Manager,
 	return fm, nil
 }
 
-func createFW(iface IFaceMapper) (firewall.Manager, error) {
+func createFW(iface IFaceMapper, mtu uint16) (firewall.Manager, error) {
 	switch check() {
 	case IPTABLES:
 		log.Info("creating an iptables firewall manager")
-		return nbiptables.Create(iface)
+		return nbiptables.Create(iface, mtu)
 	case NFTABLES:
 		log.Info("creating an nftables firewall manager")
-		return nbnftables.Create(iface)
+		return nbnftables.Create(iface, mtu)
 	default:
 		log.Info("no firewall manager found, trying to use userspace packet filtering firewall")
 		return nil, errors.New("no firewall manager found")
 	}
 }
 
-func createUserspaceFirewall(iface IFaceMapper, fm firewall.Manager, disableServerRoutes bool, flowLogger nftypes.FlowLogger) (firewall.Manager, error) {
+func createUserspaceFirewall(iface IFaceMapper, fm firewall.Manager, disableServerRoutes bool, flowLogger nftypes.FlowLogger, mtu uint16) (firewall.Manager, error) {
 	var errUsp error
 	if fm != nil {
-		fm, errUsp = uspfilter.CreateWithNativeFirewall(iface, fm, disableServerRoutes, flowLogger)
+		fm, errUsp = uspfilter.CreateWithNativeFirewall(iface, fm, disableServerRoutes, flowLogger, mtu)
 	} else {
-		fm, errUsp = uspfilter.Create(iface, disableServerRoutes, flowLogger)
+		fm, errUsp = uspfilter.Create(iface, disableServerRoutes, flowLogger, mtu)
 	}
 
 	if errUsp != nil {

client/firewall/iptables/acl_linux.go

@@ -12,7 +12,7 @@ import (
 
 	firewall "github.com/netbirdio/netbird/client/firewall/manager"
 	"github.com/netbirdio/netbird/client/internal/statemanager"
-	nbnet "github.com/netbirdio/netbird/util/net"
+	nbnet "github.com/netbirdio/netbird/client/net"
 )
 
 const (
@@ -400,7 +400,6 @@ func transformIPsetName(ipsetName string, sPort, dPort *firewall.Port, action fi
 		return ""
 	}
 
-	// Include action in the ipset name to prevent squashing rules with different actions
 	actionSuffix := ""
 	if action == firewall.ActionDrop {
 		actionSuffix = "-drop"

client/firewall/iptables/manager_linux.go

@@ -36,7 +36,7 @@ type iFaceMapper interface {
 }
 
 // Create iptables firewall manager
-func Create(wgIface iFaceMapper) (*Manager, error) {
+func Create(wgIface iFaceMapper, mtu uint16) (*Manager, error) {
 	iptablesClient, err := iptables.NewWithProtocol(iptables.ProtocolIPv4)
 	if err != nil {
 		return nil, fmt.Errorf("init iptables: %w", err)
@@ -47,7 +47,7 @@ func Create(wgIface iFaceMapper) (*Manager, error) {
 		ipv4Client: iptablesClient,
 	}
 
-	m.router, err = newRouter(iptablesClient, wgIface)
+	m.router, err = newRouter(iptablesClient, wgIface, mtu)
 	if err != nil {
 		return nil, fmt.Errorf("create router: %w", err)
 	}
@@ -66,6 +66,7 @@ func (m *Manager) Init(stateManager *statemanager.Manager) error {
 			NameStr:       m.wgIface.Name(),
 			WGAddress:     m.wgIface.Address(),
 			UserspaceBind: m.wgIface.IsUserspaceBind(),
+			MTU:           m.router.mtu,
 		},
 	}
 	stateManager.RegisterState(state)
@@ -260,6 +261,22 @@ func (m *Manager) UpdateSet(set firewall.Set, prefixes []netip.Prefix) error {
 	return m.router.UpdateSet(set, prefixes)
 }
 
+// AddInboundDNAT adds an inbound DNAT rule redirecting traffic from NetBird peers to local services.
+func (m *Manager) AddInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	return m.router.AddInboundDNAT(localAddr, protocol, sourcePort, targetPort)
+}
+
+// RemoveInboundDNAT removes an inbound DNAT rule.
+func (m *Manager) RemoveInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	return m.router.RemoveInboundDNAT(localAddr, protocol, sourcePort, targetPort)
+}
+
 func getConntrackEstablished() []string {
 	return []string{"-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT"}
 }

client/firewall/iptables/manager_linux_test.go

@@ -11,6 +11,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	fw "github.com/netbirdio/netbird/client/firewall/manager"
+	"github.com/netbirdio/netbird/client/iface"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 )
 
@@ -53,7 +54,7 @@ func TestIptablesManager(t *testing.T) {
 	require.NoError(t, err)
 
 	// just check on the local interface
-	manager, err := Create(ifaceMock)
+	manager, err := Create(ifaceMock, iface.DefaultMTU)
 	require.NoError(t, err)
 	require.NoError(t, manager.Init(nil))
 
@@ -114,7 +115,7 @@ func TestIptablesManagerDenyRules(t *testing.T) {
 	ipv4Client, err := iptables.NewWithProtocol(iptables.ProtocolIPv4)
 	require.NoError(t, err)
 
-	manager, err := Create(ifaceMock)
+	manager, err := Create(ifaceMock, iface.DefaultMTU)
 	require.NoError(t, err)
 	require.NoError(t, manager.Init(nil))
 
@@ -198,7 +199,7 @@ func TestIptablesManagerIPSet(t *testing.T) {
 	}
 
 	// just check on the local interface
-	manager, err := Create(mock)
+	manager, err := Create(mock, iface.DefaultMTU)
 	require.NoError(t, err)
 	require.NoError(t, manager.Init(nil))
 
@@ -264,7 +265,7 @@ func TestIptablesCreatePerformance(t *testing.T) {
 	for _, testMax := range []int{10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000} {
 		t.Run(fmt.Sprintf("Testing %d rules", testMax), func(t *testing.T) {
 			// just check on the local interface
-			manager, err := Create(mock)
+			manager, err := Create(mock, iface.DefaultMTU)
 			require.NoError(t, err)
 			require.NoError(t, manager.Init(nil))
 			time.Sleep(time.Second)

client/firewall/iptables/router_linux.go

@@ -19,7 +19,7 @@ import (
 	"github.com/netbirdio/netbird/client/internal/routemanager/ipfwdstate"
 	"github.com/netbirdio/netbird/client/internal/routemanager/refcounter"
 	"github.com/netbirdio/netbird/client/internal/statemanager"
-	nbnet "github.com/netbirdio/netbird/util/net"
+	nbnet "github.com/netbirdio/netbird/client/net"
 )
 
 // constants needed to manage and create iptable rules
@@ -30,17 +30,20 @@ const (
 
 	chainPOSTROUTING        = "POSTROUTING"
 	chainPREROUTING         = "PREROUTING"
+	chainFORWARD            = "FORWARD"
 	chainRTNAT              = "NETBIRD-RT-NAT"
 	chainRTFWDIN            = "NETBIRD-RT-FWD-IN"
 	chainRTFWDOUT           = "NETBIRD-RT-FWD-OUT"
 	chainRTPRE              = "NETBIRD-RT-PRE"
 	chainRTRDR              = "NETBIRD-RT-RDR"
+	chainRTMSSCLAMP         = "NETBIRD-RT-MSSCLAMP"
 	routingFinalForwardJump = "ACCEPT"
 	routingFinalNatJump     = "MASQUERADE"
 
 	jumpManglePre  = "jump-mangle-pre"
 	jumpNatPre     = "jump-nat-pre"
 	jumpNatPost    = "jump-nat-post"
+	jumpMSSClamp   = "jump-mss-clamp"
 	markManglePre  = "mark-mangle-pre"
 	markManglePost = "mark-mangle-post"
 	matchSet       = "--match-set"
@@ -48,6 +51,9 @@ const (
 	dnatSuffix = "_dnat"
 	snatSuffix = "_snat"
 	fwdSuffix  = "_fwd"
+
+	// ipTCPHeaderMinSize represents minimum IP (20) + TCP (20) header size for MSS calculation
+	ipTCPHeaderMinSize = 40
 )
 
 type ruleInfo struct {
@@ -77,16 +83,18 @@ type router struct {
 	ipsetCounter     *ipsetCounter
 	wgIface          iFaceMapper
 	legacyManagement bool
+	mtu              uint16
 
 	stateManager *statemanager.Manager
 	ipFwdState   *ipfwdstate.IPForwardingState
 }
 
-func newRouter(iptablesClient *iptables.IPTables, wgIface iFaceMapper) (*router, error) {
+func newRouter(iptablesClient *iptables.IPTables, wgIface iFaceMapper, mtu uint16) (*router, error) {
 	r := &router{
 		iptablesClient: iptablesClient,
 		rules:          make(map[string][]string),
 		wgIface:        wgIface,
+		mtu:            mtu,
 		ipFwdState:     ipfwdstate.NewIPForwardingState(),
 	}
 
@@ -392,6 +400,7 @@ func (r *router) cleanUpDefaultForwardRules() error {
 		{chainRTPRE, tableMangle},
 		{chainRTNAT, tableNat},
 		{chainRTRDR, tableNat},
+		{chainRTMSSCLAMP, tableMangle},
 	} {
 		ok, err := r.iptablesClient.ChainExists(chainInfo.table, chainInfo.chain)
 		if err != nil {
@@ -416,6 +425,7 @@ func (r *router) createContainers() error {
 		{chainRTPRE, tableMangle},
 		{chainRTNAT, tableNat},
 		{chainRTRDR, tableNat},
+		{chainRTMSSCLAMP, tableMangle},
 	} {
 		if err := r.iptablesClient.NewChain(chainInfo.table, chainInfo.chain); err != nil {
 			return fmt.Errorf("create chain %s in table %s: %w", chainInfo.chain, chainInfo.table, err)
@@ -438,6 +448,10 @@ func (r *router) createContainers() error {
 		return fmt.Errorf("add jump rules: %w", err)
 	}
 
+	if err := r.addMSSClampingRules(); err != nil {
+		log.Errorf("failed to add MSS clamping rules: %s", err)
+	}
+
 	return nil
 }
 
@@ -518,6 +532,35 @@ func (r *router) addPostroutingRules() error {
 	return nil
 }
 
+// addMSSClampingRules adds MSS clamping rules to prevent fragmentation for forwarded traffic.
+// TODO: Add IPv6 support
+func (r *router) addMSSClampingRules() error {
+	mss := r.mtu - ipTCPHeaderMinSize
+
+	// Add jump rule from FORWARD chain in mangle table to our custom chain
+	jumpRule := []string{
+		"-j", chainRTMSSCLAMP,
+	}
+	if err := r.iptablesClient.Insert(tableMangle, chainFORWARD, 1, jumpRule...); err != nil {
+		return fmt.Errorf("add jump to MSS clamp chain: %w", err)
+	}
+	r.rules[jumpMSSClamp] = jumpRule
+
+	ruleOut := []string{
+		"-o", r.wgIface.Name(),
+		"-p", "tcp",
+		"--tcp-flags", "SYN,RST", "SYN",
+		"-j", "TCPMSS",
+		"--set-mss", fmt.Sprintf("%d", mss),
+	}
+	if err := r.iptablesClient.Append(tableMangle, chainRTMSSCLAMP, ruleOut...); err != nil {
+		return fmt.Errorf("add outbound MSS clamp rule: %w", err)
+	}
+	r.rules["mss-clamp-out"] = ruleOut
+
+	return nil
+}
+
 func (r *router) insertEstablishedRule(chain string) error {
 	establishedRule := getConntrackEstablished()
 
@@ -558,7 +601,7 @@ func (r *router) addJumpRules() error {
 }
 
 func (r *router) cleanJumpRules() error {
-	for _, ruleKey := range []string{jumpNatPost, jumpManglePre, jumpNatPre} {
+	for _, ruleKey := range []string{jumpNatPost, jumpManglePre, jumpNatPre, jumpMSSClamp} {
 		if rule, exists := r.rules[ruleKey]; exists {
 			var table, chain string
 			switch ruleKey {
@@ -571,6 +614,9 @@ func (r *router) cleanJumpRules() error {
 			case jumpNatPre:
 				table = tableNat
 				chain = chainPREROUTING
+			case jumpMSSClamp:
+				table = tableMangle
+				chain = chainFORWARD
 			default:
 				return fmt.Errorf("unknown jump rule: %s", ruleKey)
 			}
@@ -880,6 +926,54 @@ func (r *router) UpdateSet(set firewall.Set, prefixes []netip.Prefix) error {
 	return nberrors.FormatErrorOrNil(merr)
 }
 
+// AddInboundDNAT adds an inbound DNAT rule redirecting traffic from NetBird peers to local services.
+func (r *router) AddInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	ruleID := fmt.Sprintf("inbound-dnat-%s-%s-%d-%d", localAddr.String(), protocol, sourcePort, targetPort)
+
+	if _, exists := r.rules[ruleID]; exists {
+		return nil
+	}
+
+	dnatRule := []string{
+		"-i", r.wgIface.Name(),
+		"-p", strings.ToLower(string(protocol)),
+		"--dport", strconv.Itoa(int(sourcePort)),
+		"-d", localAddr.String(),
+		"-m", "addrtype", "--dst-type", "LOCAL",
+		"-j", "DNAT",
+		"--to-destination", ":" + strconv.Itoa(int(targetPort)),
+	}
+
+	ruleInfo := ruleInfo{
+		table: tableNat,
+		chain: chainRTRDR,
+		rule:  dnatRule,
+	}
+
+	if err := r.iptablesClient.Append(ruleInfo.table, ruleInfo.chain, ruleInfo.rule...); err != nil {
+		return fmt.Errorf("add inbound DNAT rule: %w", err)
+	}
+	r.rules[ruleID] = ruleInfo.rule
+
+	r.updateState()
+	return nil
+}
+
+// RemoveInboundDNAT removes an inbound DNAT rule.
+func (r *router) RemoveInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	ruleID := fmt.Sprintf("inbound-dnat-%s-%s-%d-%d", localAddr.String(), protocol, sourcePort, targetPort)
+
+	if dnatRule, exists := r.rules[ruleID]; exists {
+		if err := r.iptablesClient.Delete(tableNat, chainRTRDR, dnatRule...); err != nil {
+			return fmt.Errorf("delete inbound DNAT rule: %w", err)
+		}
+		delete(r.rules, ruleID)
+	}
+
+	r.updateState()
+	return nil
+}
+
 func applyPort(flag string, port *firewall.Port) []string {
 	if port == nil {
 		return nil

client/firewall/iptables/router_linux_test.go

@@ -14,7 +14,8 @@ import (
 
 	firewall "github.com/netbirdio/netbird/client/firewall/manager"
 	"github.com/netbirdio/netbird/client/firewall/test"
-	nbnet "github.com/netbirdio/netbird/util/net"
+	"github.com/netbirdio/netbird/client/iface"
+	nbnet "github.com/netbirdio/netbird/client/net"
 )
 
 func isIptablesSupported() bool {
@@ -30,7 +31,7 @@ func TestIptablesManager_RestoreOrCreateContainers(t *testing.T) {
 	iptablesClient, err := iptables.NewWithProtocol(iptables.ProtocolIPv4)
 	require.NoError(t, err, "failed to init iptables client")
 
-	manager, err := newRouter(iptablesClient, ifaceMock)
+	manager, err := newRouter(iptablesClient, ifaceMock, iface.DefaultMTU)
 	require.NoError(t, err, "should return a valid iptables manager")
 	require.NoError(t, manager.init(nil))
 
@@ -38,7 +39,6 @@ func TestIptablesManager_RestoreOrCreateContainers(t *testing.T) {
 		assert.NoError(t, manager.Reset(), "shouldn't return error")
 	}()
 
-	// Now 5 rules:
 	// 1. established rule forward in
 	// 2. estbalished rule forward out
 	// 3. jump rule to POST nat chain
@@ -48,7 +48,9 @@ func TestIptablesManager_RestoreOrCreateContainers(t *testing.T) {
 	// 7. static return masquerade rule
 	// 8. mangle prerouting mark rule
 	// 9. mangle postrouting mark rule
-	require.Len(t, manager.rules, 9, "should have created rules map")
+	// 10. jump rule to MSS clamping chain
+	// 11. MSS clamping rule for outbound traffic
+	require.Len(t, manager.rules, 11, "should have created rules map")
 
 	exists, err := manager.iptablesClient.Exists(tableNat, chainPOSTROUTING, "-j", chainRTNAT)
 	require.NoError(t, err, "should be able to query the iptables %s table and %s chain", tableNat, chainPOSTROUTING)
@@ -82,7 +84,7 @@ func TestIptablesManager_AddNatRule(t *testing.T) {
 			iptablesClient, err := iptables.NewWithProtocol(iptables.ProtocolIPv4)
 			require.NoError(t, err, "failed to init iptables client")
 
-			manager, err := newRouter(iptablesClient, ifaceMock)
+			manager, err := newRouter(iptablesClient, ifaceMock, iface.DefaultMTU)
 			require.NoError(t, err, "shouldn't return error")
 			require.NoError(t, manager.init(nil))
 
@@ -155,7 +157,7 @@ func TestIptablesManager_RemoveNatRule(t *testing.T) {
 		t.Run(testCase.Name, func(t *testing.T) {
 			iptablesClient, _ := iptables.NewWithProtocol(iptables.ProtocolIPv4)
 
-			manager, err := newRouter(iptablesClient, ifaceMock)
+			manager, err := newRouter(iptablesClient, ifaceMock, iface.DefaultMTU)
 			require.NoError(t, err, "shouldn't return error")
 			require.NoError(t, manager.init(nil))
 			defer func() {
@@ -217,7 +219,7 @@ func TestRouter_AddRouteFiltering(t *testing.T) {
 	iptablesClient, err := iptables.NewWithProtocol(iptables.ProtocolIPv4)
 	require.NoError(t, err, "Failed to create iptables client")
 
-	r, err := newRouter(iptablesClient, ifaceMock)
+	r, err := newRouter(iptablesClient, ifaceMock, iface.DefaultMTU)
 	require.NoError(t, err, "Failed to create router manager")
 	require.NoError(t, r.init(nil))
 

client/firewall/iptables/state_linux.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"sync"
 
+	"github.com/netbirdio/netbird/client/iface"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 )
 
@@ -11,6 +12,7 @@ type InterfaceState struct {
 	NameStr       string         `json:"name"`
 	WGAddress     wgaddr.Address `json:"wg_address"`
 	UserspaceBind bool           `json:"userspace_bind"`
+	MTU           uint16         `json:"mtu"`
 }
 
 func (i *InterfaceState) Name() string {
@@ -42,7 +44,11 @@ func (s *ShutdownState) Name() string {
 }
 
 func (s *ShutdownState) Cleanup() error {
-	ipt, err := Create(s.InterfaceState)
+	mtu := s.InterfaceState.MTU
+	if mtu == 0 {
+		mtu = iface.DefaultMTU
+	}
+	ipt, err := Create(s.InterfaceState, mtu)
 	if err != nil {
 		return fmt.Errorf("create iptables manager: %w", err)
 	}

client/firewall/manager/firewall.go

@@ -100,6 +100,9 @@ type Manager interface {
 	//
 	// If comment argument is empty firewall manager should set
 	// rule ID as comment for the rule
+	//
+	// Note: Callers should call Flush() after adding rules to ensure
+	// they are applied to the kernel and rule handles are refreshed.
 	AddPeerFiltering(
 		id []byte,
 		ip net.IP,
@@ -151,14 +154,20 @@ type Manager interface {
 
 	DisableRouting() error
 
-	// AddDNATRule adds a DNAT rule
+	// AddDNATRule adds outbound DNAT rule for forwarding external traffic to the NetBird network.
 	AddDNATRule(ForwardRule) (Rule, error)
 
-	// DeleteDNATRule deletes a DNAT rule
+	// DeleteDNATRule deletes the outbound DNAT rule.
 	DeleteDNATRule(Rule) error
 
 	// UpdateSet updates the set with the given prefixes
 	UpdateSet(hash Set, prefixes []netip.Prefix) error
+
+	// AddInboundDNAT adds an inbound DNAT rule redirecting traffic from NetBird peers to local services
+	AddInboundDNAT(localAddr netip.Addr, protocol Protocol, sourcePort, targetPort uint16) error
+
+	// RemoveInboundDNAT removes inbound DNAT rule
+	RemoveInboundDNAT(localAddr netip.Addr, protocol Protocol, sourcePort, targetPort uint16) error
 }
 
 func GenKey(format string, pair RouterPair) string {

client/firewall/nftables/acl_linux.go

@@ -16,7 +16,7 @@ import (
 	"golang.org/x/sys/unix"
 
 	firewall "github.com/netbirdio/netbird/client/firewall/manager"
-	nbnet "github.com/netbirdio/netbird/util/net"
+	nbnet "github.com/netbirdio/netbird/client/net"
 )
 
 const (
@@ -29,8 +29,6 @@ const (
 	chainNameForwardFilter     = "netbird-acl-forward-filter"
 	chainNameManglePrerouting  = "netbird-mangle-prerouting"
 	chainNameManglePostrouting = "netbird-mangle-postrouting"
-
-	allowNetbirdInputRuleID = "allow Netbird incoming traffic"
 )
 
 const flushError = "flush: %w"
@@ -195,25 +193,6 @@ func (m *AclManager) DeletePeerRule(rule firewall.Rule) error {
 // createDefaultAllowRules creates default allow rules for the input and output chains
 func (m *AclManager) createDefaultAllowRules() error {
 	expIn := []expr.Any{
-		&expr.Payload{
-			DestRegister: 1,
-			Base:         expr.PayloadBaseNetworkHeader,
-			Offset:       12,
-			Len:          4,
-		},
-		// mask
-		&expr.Bitwise{
-			SourceRegister: 1,
-			DestRegister:   1,
-			Len:            4,
-			Mask:           []byte{0, 0, 0, 0},
-			Xor:            []byte{0, 0, 0, 0},
-		},
-		// net address
-		&expr.Cmp{
-			Register: 1,
-			Data:     []byte{0, 0, 0, 0},
-		},
 		&expr.Verdict{
 			Kind: expr.VerdictAccept,
 		},
@@ -258,7 +237,7 @@ func (m *AclManager) addIOFiltering(
 	action firewall.Action,
 	ipset *nftables.Set,
 ) (*Rule, error) {
-	ruleId := generatePeerRuleId(ip, sPort, dPort, action, ipset)
+	ruleId := generatePeerRuleId(ip, proto, sPort, dPort, action, ipset)
 	if r, ok := m.rules[ruleId]; ok {
 		return &Rule{
 			nftRule:    r.nftRule,
@@ -357,11 +336,12 @@ func (m *AclManager) addIOFiltering(
 	}
 
 	if err := m.rConn.Flush(); err != nil {
-		return nil, fmt.Errorf(flushError, err)
+		return nil, fmt.Errorf("flush input rule %s: %v", ruleId, err)
 	}
 
 	ruleStruct := &Rule{
-		nftRule:    nftRule,
+		nftRule: nftRule,
+		// best effort mangle rule
 		mangleRule: m.createPreroutingRule(expressions, userData),
 		nftSet:     ipset,
 		ruleID:     ruleId,
@@ -420,12 +400,19 @@ func (m *AclManager) createPreroutingRule(expressions []expr.Any, userData []byt
 		},
 	)
 
-	return m.rConn.AddRule(&nftables.Rule{
+	nfRule := m.rConn.AddRule(&nftables.Rule{
 		Table:    m.workTable,
 		Chain:    m.chainPrerouting,
 		Exprs:    preroutingExprs,
 		UserData: userData,
 	})
+
+	if err := m.rConn.Flush(); err != nil {
+		log.Errorf("failed to flush mangle rule %s: %v", string(userData), err)
+		return nil
+	}
+
+	return nfRule
 }
 
 func (m *AclManager) createDefaultChains() (err error) {
@@ -697,8 +684,8 @@ func (m *AclManager) refreshRuleHandles(chain *nftables.Chain, mangle bool) erro
 	return nil
 }
 
-func generatePeerRuleId(ip net.IP, sPort *firewall.Port, dPort *firewall.Port, action firewall.Action, ipset *nftables.Set) string {
-	rulesetID := ":"
+func generatePeerRuleId(ip net.IP, proto firewall.Protocol, sPort *firewall.Port, dPort *firewall.Port, action firewall.Action, ipset *nftables.Set) string {
+	rulesetID := ":" + string(proto) + ":"
 	if sPort != nil {
 		rulesetID += sPort.String()
 	}

client/firewall/nftables/manager_linux.go

@@ -1,11 +1,11 @@
 package nftables
 
 import (
-	"bytes"
 	"context"
 	"fmt"
 	"net"
 	"net/netip"
+	"os"
 	"sync"
 
 	"github.com/google/nftables"
@@ -19,13 +19,22 @@ import (
 )
 
 const (
-	// tableNameNetbird is the name of the table that is used for filtering by the Netbird client
+	// tableNameNetbird is the default name of the table that is used for filtering by the Netbird client
 	tableNameNetbird = "netbird"
+	// envTableName is the environment variable to override the table name
+	envTableName = "NB_NFTABLES_TABLE"
 
 	tableNameFilter = "filter"
 	chainNameInput  = "INPUT"
 )
 
+func getTableName() string {
+	if name := os.Getenv(envTableName); name != "" {
+		return name
+	}
+	return tableNameNetbird
+}
+
 // iFaceMapper defines subset methods of interface required for manager
 type iFaceMapper interface {
 	Name() string
@@ -44,16 +53,16 @@ type Manager struct {
 }
 
 // Create nftables firewall manager
-func Create(wgIface iFaceMapper) (*Manager, error) {
+func Create(wgIface iFaceMapper, mtu uint16) (*Manager, error) {
 	m := &Manager{
 		rConn:   &nftables.Conn{},
 		wgIface: wgIface,
 	}
 
-	workTable := &nftables.Table{Name: tableNameNetbird, Family: nftables.TableFamilyIPv4}
+	workTable := &nftables.Table{Name: getTableName(), Family: nftables.TableFamilyIPv4}
 
 	var err error
-	m.router, err = newRouter(workTable, wgIface)
+	m.router, err = newRouter(workTable, wgIface, mtu)
 	if err != nil {
 		return nil, fmt.Errorf("create router: %w", err)
 	}
@@ -93,6 +102,7 @@ func (m *Manager) Init(stateManager *statemanager.Manager) error {
 			NameStr:       m.wgIface.Name(),
 			WGAddress:     m.wgIface.Address(),
 			UserspaceBind: m.wgIface.IsUserspaceBind(),
+			MTU:           m.router.mtu,
 		},
 	}); err != nil {
 		log.Errorf("failed to update state: %v", err)
@@ -197,44 +207,11 @@ func (m *Manager) AllowNetbird() error {
 	m.mutex.Lock()
 	defer m.mutex.Unlock()
 
-	err := m.aclManager.createDefaultAllowRules()
-	if err != nil {
-		return fmt.Errorf("failed to create default allow rules: %v", err)
+	if err := m.aclManager.createDefaultAllowRules(); err != nil {
+		return fmt.Errorf("create default allow rules: %w", err)
 	}
-
-	chains, err := m.rConn.ListChainsOfTableFamily(nftables.TableFamilyIPv4)
-	if err != nil {
-		return fmt.Errorf("list of chains: %w", err)
-	}
-
-	var chain *nftables.Chain
-	for _, c := range chains {
-		if c.Table.Name == tableNameFilter && c.Name == chainNameInput {
-			chain = c
-			break
-		}
-	}
-
-	if chain == nil {
-		log.Debugf("chain INPUT not found. Skipping add allow netbird rule")
-		return nil
-	}
-
-	rules, err := m.rConn.GetRules(chain.Table, chain)
-	if err != nil {
-		return fmt.Errorf("failed to get rules for the INPUT chain: %v", err)
-	}
-
-	if rule := m.detectAllowNetbirdRule(rules); rule != nil {
-		log.Debugf("allow netbird rule already exists: %v", rule)
-		return nil
-	}
-
-	m.applyAllowNetbirdRules(chain)
-
-	err = m.rConn.Flush()
-	if err != nil {
-		return fmt.Errorf("failed to flush allow input netbird rules: %v", err)
+	if err := m.rConn.Flush(); err != nil {
+		return fmt.Errorf("flush allow input netbird rules: %w", err)
 	}
 
 	return nil
@@ -250,10 +227,6 @@ func (m *Manager) Close(stateManager *statemanager.Manager) error {
 	m.mutex.Lock()
 	defer m.mutex.Unlock()
 
-	if err := m.resetNetbirdInputRules(); err != nil {
-		return fmt.Errorf("reset netbird input rules: %v", err)
-	}
-
 	if err := m.router.Reset(); err != nil {
 		return fmt.Errorf("reset router: %v", err)
 	}
@@ -273,49 +246,15 @@ func (m *Manager) Close(stateManager *statemanager.Manager) error {
 	return nil
 }
 
-func (m *Manager) resetNetbirdInputRules() error {
-	chains, err := m.rConn.ListChains()
-	if err != nil {
-		return fmt.Errorf("list chains: %w", err)
-	}
-
-	m.deleteNetbirdInputRules(chains)
-
-	return nil
-}
-
-func (m *Manager) deleteNetbirdInputRules(chains []*nftables.Chain) {
-	for _, c := range chains {
-		if c.Table.Name == tableNameFilter && c.Name == chainNameInput {
-			rules, err := m.rConn.GetRules(c.Table, c)
-			if err != nil {
-				log.Errorf("get rules for chain %q: %v", c.Name, err)
-				continue
-			}
-
-			m.deleteMatchingRules(rules)
-		}
-	}
-}
-
-func (m *Manager) deleteMatchingRules(rules []*nftables.Rule) {
-	for _, r := range rules {
-		if bytes.Equal(r.UserData, []byte(allowNetbirdInputRuleID)) {
-			if err := m.rConn.DelRule(r); err != nil {
-				log.Errorf("delete rule: %v", err)
-			}
-		}
-	}
-}
-
 func (m *Manager) cleanupNetbirdTables() error {
 	tables, err := m.rConn.ListTables()
 	if err != nil {
 		return fmt.Errorf("list tables: %w", err)
 	}
 
+	tableName := getTableName()
 	for _, t := range tables {
-		if t.Name == tableNameNetbird {
+		if t.Name == tableName {
 			m.rConn.DelTable(t)
 		}
 	}
@@ -376,61 +315,40 @@ func (m *Manager) UpdateSet(set firewall.Set, prefixes []netip.Prefix) error {
 	return m.router.UpdateSet(set, prefixes)
 }
 
+// AddInboundDNAT adds an inbound DNAT rule redirecting traffic from NetBird peers to local services.
+func (m *Manager) AddInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	return m.router.AddInboundDNAT(localAddr, protocol, sourcePort, targetPort)
+}
+
+// RemoveInboundDNAT removes an inbound DNAT rule.
+func (m *Manager) RemoveInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	return m.router.RemoveInboundDNAT(localAddr, protocol, sourcePort, targetPort)
+}
+
 func (m *Manager) createWorkTable() (*nftables.Table, error) {
 	tables, err := m.rConn.ListTablesOfFamily(nftables.TableFamilyIPv4)
 	if err != nil {
 		return nil, fmt.Errorf("list of tables: %w", err)
 	}
 
+	tableName := getTableName()
 	for _, t := range tables {
-		if t.Name == tableNameNetbird {
+		if t.Name == tableName {
 			m.rConn.DelTable(t)
 		}
 	}
 
-	table := m.rConn.AddTable(&nftables.Table{Name: tableNameNetbird, Family: nftables.TableFamilyIPv4})
+	table := m.rConn.AddTable(&nftables.Table{Name: getTableName(), Family: nftables.TableFamilyIPv4})
 	err = m.rConn.Flush()
 	return table, err
 }
 
-func (m *Manager) applyAllowNetbirdRules(chain *nftables.Chain) {
-	rule := &nftables.Rule{
-		Table: chain.Table,
-		Chain: chain,
-		Exprs: []expr.Any{
-			&expr.Meta{Key: expr.MetaKeyIIFNAME, Register: 1},
-			&expr.Cmp{
-				Op:       expr.CmpOpEq,
-				Register: 1,
-				Data:     ifname(m.wgIface.Name()),
-			},
-			&expr.Verdict{
-				Kind: expr.VerdictAccept,
-			},
-		},
-		UserData: []byte(allowNetbirdInputRuleID),
-	}
-	_ = m.rConn.InsertRule(rule)
-}
-
-func (m *Manager) detectAllowNetbirdRule(existedRules []*nftables.Rule) *nftables.Rule {
-	ifName := ifname(m.wgIface.Name())
-	for _, rule := range existedRules {
-		if rule.Table.Name == tableNameFilter && rule.Chain.Name == chainNameInput {
-			if len(rule.Exprs) < 4 {
-				if e, ok := rule.Exprs[0].(*expr.Meta); !ok || e.Key != expr.MetaKeyIIFNAME {
-					continue
-				}
-				if e, ok := rule.Exprs[1].(*expr.Cmp); !ok || e.Op != expr.CmpOpEq || !bytes.Equal(e.Data, ifName) {
-					continue
-				}
-				return rule
-			}
-		}
-	}
-	return nil
-}
-
 func insertReturnTrafficRule(conn *nftables.Conn, table *nftables.Table, chain *nftables.Chain) {
 	rule := &nftables.Rule{
 		Table: table,

client/firewall/nftables/manager_linux_test.go

@@ -16,6 +16,7 @@ import (
 	"golang.org/x/sys/unix"
 
 	fw "github.com/netbirdio/netbird/client/firewall/manager"
+	"github.com/netbirdio/netbird/client/iface"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 )
 
@@ -56,7 +57,7 @@ func (i *iFaceMock) IsUserspaceBind() bool { return false }
 func TestNftablesManager(t *testing.T) {
 
 	// just check on the local interface
-	manager, err := Create(ifaceMock)
+	manager, err := Create(ifaceMock, iface.DefaultMTU)
 	require.NoError(t, err)
 	require.NoError(t, manager.Init(nil))
 	time.Sleep(time.Second * 3)
@@ -168,7 +169,7 @@ func TestNftablesManager(t *testing.T) {
 func TestNftablesManagerRuleOrder(t *testing.T) {
 	// This test verifies rule insertion order in nftables peer ACLs
 	// We add accept rule first, then deny rule to test ordering behavior
-	manager, err := Create(ifaceMock)
+	manager, err := Create(ifaceMock, iface.DefaultMTU)
 	require.NoError(t, err)
 	require.NoError(t, manager.Init(nil))
 
@@ -261,7 +262,7 @@ func TestNFtablesCreatePerformance(t *testing.T) {
 	for _, testMax := range []int{10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000} {
 		t.Run(fmt.Sprintf("Testing %d rules", testMax), func(t *testing.T) {
 			// just check on the local interface
-			manager, err := Create(mock)
+			manager, err := Create(mock, iface.DefaultMTU)
 			require.NoError(t, err)
 			require.NoError(t, manager.Init(nil))
 			time.Sleep(time.Second * 3)
@@ -345,7 +346,7 @@ func TestNftablesManagerCompatibilityWithIptables(t *testing.T) {
 	stdout, stderr := runIptablesSave(t)
 	verifyIptablesOutput(t, stdout, stderr)
 
-	manager, err := Create(ifaceMock)
+	manager, err := Create(ifaceMock, iface.DefaultMTU)
 	require.NoError(t, err, "failed to create manager")
 	require.NoError(t, manager.Init(nil))
 

client/firewall/nftables/router_linux.go

@@ -16,13 +16,14 @@ import (
 	"github.com/google/nftables/xt"
 	"github.com/hashicorp/go-multierror"
 	log "github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
 
 	nberrors "github.com/netbirdio/netbird/client/errors"
 	firewall "github.com/netbirdio/netbird/client/firewall/manager"
 	nbid "github.com/netbirdio/netbird/client/internal/acl/id"
 	"github.com/netbirdio/netbird/client/internal/routemanager/ipfwdstate"
 	"github.com/netbirdio/netbird/client/internal/routemanager/refcounter"
-	nbnet "github.com/netbirdio/netbird/util/net"
+	nbnet "github.com/netbirdio/netbird/client/net"
 )
 
 const (
@@ -32,12 +33,17 @@ const (
 	chainNameRoutingNat    = "netbird-rt-postrouting"
 	chainNameRoutingRdr    = "netbird-rt-redirect"
 	chainNameForward       = "FORWARD"
+	chainNameMangleForward = "netbird-mangle-forward"
 
 	userDataAcceptForwardRuleIif = "frwacceptiif"
 	userDataAcceptForwardRuleOif = "frwacceptoif"
+	userDataAcceptInputRule      = "inputaccept"
 
 	dnatSuffix = "_dnat"
 	snatSuffix = "_snat"
+
+	// ipTCPHeaderMinSize represents minimum IP (20) + TCP (20) header size for MSS calculation
+	ipTCPHeaderMinSize = 40
 )
 
 const refreshRulesMapError = "refresh rules map: %w"
@@ -63,9 +69,10 @@ type router struct {
 	wgIface          iFaceMapper
 	ipFwdState       *ipfwdstate.IPForwardingState
 	legacyManagement bool
+	mtu              uint16
 }
 
-func newRouter(workTable *nftables.Table, wgIface iFaceMapper) (*router, error) {
+func newRouter(workTable *nftables.Table, wgIface iFaceMapper, mtu uint16) (*router, error) {
 	r := &router{
 		conn:       &nftables.Conn{},
 		workTable:  workTable,
@@ -73,6 +80,7 @@ func newRouter(workTable *nftables.Table, wgIface iFaceMapper) (*router, error)
 		rules:      make(map[string]*nftables.Rule),
 		wgIface:    wgIface,
 		ipFwdState: ipfwdstate.NewIPForwardingState(),
+		mtu:        mtu,
 	}
 
 	r.ipsetCounter = refcounter.New(
@@ -96,8 +104,8 @@ func newRouter(workTable *nftables.Table, wgIface iFaceMapper) (*router, error)
 func (r *router) init(workTable *nftables.Table) error {
 	r.workTable = workTable
 
-	if err := r.removeAcceptForwardRules(); err != nil {
-		log.Errorf("failed to clean up rules from FORWARD chain: %s", err)
+	if err := r.removeAcceptFilterRules(); err != nil {
+		log.Errorf("failed to clean up rules from filter table: %s", err)
 	}
 
 	if err := r.createContainers(); err != nil {
@@ -111,15 +119,15 @@ func (r *router) init(workTable *nftables.Table) error {
 	return nil
 }
 
-// Reset cleans existing nftables default forward rules from the system
+// Reset cleans existing nftables filter table rules from the system
 func (r *router) Reset() error {
 	// clear without deleting the ipsets, the nf table will be deleted by the caller
 	r.ipsetCounter.Clear()
 
 	var merr *multierror.Error
 
-	if err := r.removeAcceptForwardRules(); err != nil {
-		merr = multierror.Append(merr, fmt.Errorf("remove accept forward rules: %w", err))
+	if err := r.removeAcceptFilterRules(); err != nil {
+		merr = multierror.Append(merr, fmt.Errorf("remove accept filter rules: %w", err))
 	}
 
 	if err := r.removeNatPreroutingRules(); err != nil {
@@ -220,11 +228,23 @@ func (r *router) createContainers() error {
 		Type:     nftables.ChainTypeFilter,
 	})
 
+	r.chains[chainNameMangleForward] = r.conn.AddChain(&nftables.Chain{
+		Name:     chainNameMangleForward,
+		Table:    r.workTable,
+		Hooknum:  nftables.ChainHookForward,
+		Priority: nftables.ChainPriorityMangle,
+		Type:     nftables.ChainTypeFilter,
+	})
+
 	// Add the single NAT rule that matches on mark
 	if err := r.addPostroutingRules(); err != nil {
 		return fmt.Errorf("add single nat rule: %v", err)
 	}
 
+	if err := r.addMSSClampingRules(); err != nil {
+		log.Errorf("failed to add MSS clamping rules: %s", err)
+	}
+
 	if err := r.acceptForwardRules(); err != nil {
 		log.Errorf("failed to add accept rules for the forward chain: %s", err)
 	}
@@ -745,6 +765,83 @@ func (r *router) addPostroutingRules() error {
 	return nil
 }
 
+// addMSSClampingRules adds MSS clamping rules to prevent fragmentation for forwarded traffic.
+// TODO: Add IPv6 support
+func (r *router) addMSSClampingRules() error {
+	mss := r.mtu - ipTCPHeaderMinSize
+
+	exprsOut := []expr.Any{
+		&expr.Meta{
+			Key:      expr.MetaKeyOIFNAME,
+			Register: 1,
+		},
+		&expr.Cmp{
+			Op:       expr.CmpOpEq,
+			Register: 1,
+			Data:     ifname(r.wgIface.Name()),
+		},
+		&expr.Meta{
+			Key:      expr.MetaKeyL4PROTO,
+			Register: 1,
+		},
+		&expr.Cmp{
+			Op:       expr.CmpOpEq,
+			Register: 1,
+			Data:     []byte{unix.IPPROTO_TCP},
+		},
+		&expr.Payload{
+			DestRegister: 1,
+			Base:         expr.PayloadBaseTransportHeader,
+			Offset:       13,
+			Len:          1,
+		},
+		&expr.Bitwise{
+			DestRegister:   1,
+			SourceRegister: 1,
+			Len:            1,
+			Mask:           []byte{0x02},
+			Xor:            []byte{0x00},
+		},
+		&expr.Cmp{
+			Op:       expr.CmpOpNeq,
+			Register: 1,
+			Data:     []byte{0x00},
+		},
+		&expr.Counter{},
+		&expr.Exthdr{
+			DestRegister: 1,
+			Type:         2,
+			Offset:       2,
+			Len:          2,
+			Op:           expr.ExthdrOpTcpopt,
+		},
+		&expr.Cmp{
+			Op:       expr.CmpOpGt,
+			Register: 1,
+			Data:     binaryutil.BigEndian.PutUint16(uint16(mss)),
+		},
+		&expr.Immediate{
+			Register: 1,
+			Data:     binaryutil.BigEndian.PutUint16(uint16(mss)),
+		},
+		&expr.Exthdr{
+			SourceRegister: 1,
+			Type:           2,
+			Offset:         2,
+			Len:            2,
+			Op:             expr.ExthdrOpTcpopt,
+		},
+	}
+
+	r.conn.AddRule(&nftables.Rule{
+		Table: r.workTable,
+		Chain: r.chains[chainNameMangleForward],
+		Exprs: exprsOut,
+	})
+
+	return nil
+}
+
 // addLegacyRouteRule adds a legacy routing rule for mgmt servers pre route acls
 func (r *router) addLegacyRouteRule(pair firewall.RouterPair) error {
 	sourceExp, err := r.applyNetwork(pair.Source, nil, true)
@@ -840,6 +937,7 @@ func (r *router) RemoveAllLegacyRouteRules() error {
 // that our traffic is not dropped by existing rules there.
 // The existing FORWARD rules/policies decide outbound traffic towards our interface.
 // In case the FORWARD policy is set to "drop", we add an established/related rule to allow return traffic for the inbound rule.
+// This method also adds INPUT chain rules to allow traffic to the local interface.
 func (r *router) acceptForwardRules() error {
 	if r.filterTable == nil {
 		log.Debugf("table 'filter' not found for forward rules, skipping accept rules")
@@ -849,7 +947,7 @@ func (r *router) acceptForwardRules() error {
 	fw := "iptables"
 
 	defer func() {
-		log.Debugf("Used %s to add accept forward rules", fw)
+		log.Debugf("Used %s to add accept forward and input rules", fw)
 	}()
 
 	// Try iptables first and fallback to nftables if iptables is not available
@@ -859,22 +957,30 @@ func (r *router) acceptForwardRules() error {
 		log.Warnf("Will use nftables to manipulate the filter table because iptables is not available: %v", err)
 
 		fw = "nftables"
-		return r.acceptForwardRulesNftables()
+		return r.acceptFilterRulesNftables()
 	}
 
-	return r.acceptForwardRulesIptables(ipt)
+	return r.acceptFilterRulesIptables(ipt)
 }
 
-func (r *router) acceptForwardRulesIptables(ipt *iptables.IPTables) error {
+func (r *router) acceptFilterRulesIptables(ipt *iptables.IPTables) error {
 	var merr *multierror.Error
+
 	for _, rule := range r.getAcceptForwardRules() {
 		if err := ipt.Insert("filter", chainNameForward, 1, rule...); err != nil {
-			merr = multierror.Append(err, fmt.Errorf("add iptables rule: %v", err))
+			merr = multierror.Append(err, fmt.Errorf("add iptables forward rule: %v", err))
 		} else {
-			log.Debugf("added iptables rule: %v", rule)
+			log.Debugf("added iptables forward rule: %v", rule)
 		}
 	}
 
+	inputRule := r.getAcceptInputRule()
+	if err := ipt.Insert("filter", chainNameInput, 1, inputRule...); err != nil {
+		merr = multierror.Append(err, fmt.Errorf("add iptables input rule: %v", err))
+	} else {
+		log.Debugf("added iptables input rule: %v", inputRule)
+	}
+
 	return nberrors.FormatErrorOrNil(merr)
 }
 
@@ -886,10 +992,13 @@ func (r *router) getAcceptForwardRules() [][]string {
 	}
 }
 
-func (r *router) acceptForwardRulesNftables() error {
+func (r *router) getAcceptInputRule() []string {
+	return []string{"-i", r.wgIface.Name(), "-j", "ACCEPT"}
+}
+
+func (r *router) acceptFilterRulesNftables() error {
 	intf := ifname(r.wgIface.Name())
 
-	// Rule for incoming interface (iif) with counter
 	iifRule := &nftables.Rule{
 		Table: r.filterTable,
 		Chain: &nftables.Chain{
@@ -922,11 +1031,10 @@ func (r *router) acceptForwardRulesNftables() error {
 		},
 	}
 
-	// Rule for outgoing interface (oif) with counter
 	oifRule := &nftables.Rule{
 		Table: r.filterTable,
 		Chain: &nftables.Chain{
-			Name:     "FORWARD",
+			Name:     chainNameForward,
 			Table:    r.filterTable,
 			Type:     nftables.ChainTypeFilter,
 			Hooknum:  nftables.ChainHookForward,
@@ -935,35 +1043,60 @@ func (r *router) acceptForwardRulesNftables() error {
 		Exprs:    append(oifExprs, getEstablishedExprs(2)...),
 		UserData: []byte(userDataAcceptForwardRuleOif),
 	}
-
 	r.conn.InsertRule(oifRule)
 
+	inputRule := &nftables.Rule{
+		Table: r.filterTable,
+		Chain: &nftables.Chain{
+			Name:     chainNameInput,
+			Table:    r.filterTable,
+			Type:     nftables.ChainTypeFilter,
+			Hooknum:  nftables.ChainHookInput,
+			Priority: nftables.ChainPriorityFilter,
+		},
+		Exprs: []expr.Any{
+			&expr.Meta{Key: expr.MetaKeyIIFNAME, Register: 1},
+			&expr.Cmp{
+				Op:       expr.CmpOpEq,
+				Register: 1,
+				Data:     intf,
+			},
+			&expr.Counter{},
+			&expr.Verdict{Kind: expr.VerdictAccept},
+		},
+		UserData: []byte(userDataAcceptInputRule),
+	}
+	r.conn.InsertRule(inputRule)
+
 	return nil
 }
 
-func (r *router) removeAcceptForwardRules() error {
+func (r *router) removeAcceptFilterRules() error {
 	if r.filterTable == nil {
 		return nil
 	}
 
-	// Try iptables first and fallback to nftables if iptables is not available
 	ipt, err := iptables.New()
 	if err != nil {
 		log.Warnf("Will use nftables to manipulate the filter table because iptables is not available: %v", err)
-		return r.removeAcceptForwardRulesNftables()
+		return r.removeAcceptFilterRulesNftables()
 	}
 
-	return r.removeAcceptForwardRulesIptables(ipt)
+	return r.removeAcceptFilterRulesIptables(ipt)
 }
 
-func (r *router) removeAcceptForwardRulesNftables() error {
+func (r *router) removeAcceptFilterRulesNftables() error {
 	chains, err := r.conn.ListChainsOfTableFamily(nftables.TableFamilyIPv4)
 	if err != nil {
 		return fmt.Errorf("list chains: %v", err)
 	}
 
 	for _, chain := range chains {
-		if chain.Table.Name != r.filterTable.Name || chain.Name != chainNameForward {
+		if chain.Table.Name != r.filterTable.Name {
+			continue
+		}
+
+		if chain.Name != chainNameForward && chain.Name != chainNameInput {
 			continue
 		}
 
@@ -974,7 +1107,8 @@ func (r *router) removeAcceptForwardRulesNftables() error {
 
 		for _, rule := range rules {
 			if bytes.Equal(rule.UserData, []byte(userDataAcceptForwardRuleIif)) ||
-				bytes.Equal(rule.UserData, []byte(userDataAcceptForwardRuleOif)) {
+				bytes.Equal(rule.UserData, []byte(userDataAcceptForwardRuleOif)) ||
+				bytes.Equal(rule.UserData, []byte(userDataAcceptInputRule)) {
 				if err := r.conn.DelRule(rule); err != nil {
 					return fmt.Errorf("delete rule: %v", err)
 				}
@@ -989,14 +1123,20 @@ func (r *router) removeAcceptForwardRulesNftables() error {
 	return nil
 }
 
-func (r *router) removeAcceptForwardRulesIptables(ipt *iptables.IPTables) error {
+func (r *router) removeAcceptFilterRulesIptables(ipt *iptables.IPTables) error {
 	var merr *multierror.Error
+
 	for _, rule := range r.getAcceptForwardRules() {
 		if err := ipt.DeleteIfExists("filter", chainNameForward, rule...); err != nil {
-			merr = multierror.Append(err, fmt.Errorf("remove iptables rule: %v", err))
+			merr = multierror.Append(err, fmt.Errorf("remove iptables forward rule: %v", err))
 		}
 	}
 
+	inputRule := r.getAcceptInputRule()
+	if err := ipt.DeleteIfExists("filter", chainNameInput, inputRule...); err != nil {
+		merr = multierror.Append(err, fmt.Errorf("remove iptables input rule: %v", err))
+	}
+
 	return nberrors.FormatErrorOrNil(merr)
 }
 
@@ -1350,6 +1490,103 @@ func (r *router) UpdateSet(set firewall.Set, prefixes []netip.Prefix) error {
 	return nil
 }
 
+// AddInboundDNAT adds an inbound DNAT rule redirecting traffic from NetBird peers to local services.
+func (r *router) AddInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	ruleID := fmt.Sprintf("inbound-dnat-%s-%s-%d-%d", localAddr.String(), protocol, sourcePort, targetPort)
+
+	if _, exists := r.rules[ruleID]; exists {
+		return nil
+	}
+
+	protoNum, err := protoToInt(protocol)
+	if err != nil {
+		return fmt.Errorf("convert protocol to number: %w", err)
+	}
+
+	exprs := []expr.Any{
+		&expr.Meta{Key: expr.MetaKeyIIFNAME, Register: 1},
+		&expr.Cmp{
+			Op:       expr.CmpOpEq,
+			Register: 1,
+			Data:     ifname(r.wgIface.Name()),
+		},
+		&expr.Meta{Key: expr.MetaKeyL4PROTO, Register: 2},
+		&expr.Cmp{
+			Op:       expr.CmpOpEq,
+			Register: 2,
+			Data:     []byte{protoNum},
+		},
+		&expr.Payload{
+			DestRegister: 3,
+			Base:         expr.PayloadBaseTransportHeader,
+			Offset:       2,
+			Len:          2,
+		},
+		&expr.Cmp{
+			Op:       expr.CmpOpEq,
+			Register: 3,
+			Data:     binaryutil.BigEndian.PutUint16(sourcePort),
+		},
+	}
+
+	exprs = append(exprs, applyPrefix(netip.PrefixFrom(localAddr, 32), false)...)
+
+	exprs = append(exprs,
+		&expr.Immediate{
+			Register: 1,
+			Data:     localAddr.AsSlice(),
+		},
+		&expr.Immediate{
+			Register: 2,
+			Data:     binaryutil.BigEndian.PutUint16(targetPort),
+		},
+		&expr.NAT{
+			Type:        expr.NATTypeDestNAT,
+			Family:      uint32(nftables.TableFamilyIPv4),
+			RegAddrMin:  1,
+			RegProtoMin: 2,
+			RegProtoMax: 0,
+		},
+	)
+
+	dnatRule := &nftables.Rule{
+		Table:    r.workTable,
+		Chain:    r.chains[chainNameRoutingRdr],
+		Exprs:    exprs,
+		UserData: []byte(ruleID),
+	}
+	r.conn.AddRule(dnatRule)
+
+	if err := r.conn.Flush(); err != nil {
+		return fmt.Errorf("add inbound DNAT rule: %w", err)
+	}
+
+	r.rules[ruleID] = dnatRule
+
+	return nil
+}
+
+// RemoveInboundDNAT removes an inbound DNAT rule.
+func (r *router) RemoveInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	if err := r.refreshRulesMap(); err != nil {
+		return fmt.Errorf(refreshRulesMapError, err)
+	}
+
+	ruleID := fmt.Sprintf("inbound-dnat-%s-%s-%d-%d", localAddr.String(), protocol, sourcePort, targetPort)
+
+	if rule, exists := r.rules[ruleID]; exists {
+		if err := r.conn.DelRule(rule); err != nil {
+			return fmt.Errorf("delete inbound DNAT rule %s: %w", ruleID, err)
+		}
+		if err := r.conn.Flush(); err != nil {
+			return fmt.Errorf("flush delete inbound DNAT rule: %w", err)
+		}
+		delete(r.rules, ruleID)
+	}
+
+	return nil
+}
+
 // applyNetwork generates nftables expressions for networks (CIDR) or sets
 func (r *router) applyNetwork(
 	network firewall.Network,

client/firewall/nftables/router_linux_test.go

@@ -17,6 +17,7 @@ import (
 
 	firewall "github.com/netbirdio/netbird/client/firewall/manager"
 	"github.com/netbirdio/netbird/client/firewall/test"
+	"github.com/netbirdio/netbird/client/iface"
 )
 
 const (
@@ -36,7 +37,7 @@ func TestNftablesManager_AddNatRule(t *testing.T) {
 	for _, testCase := range test.InsertRuleTestCases {
 		t.Run(testCase.Name, func(t *testing.T) {
 			// need fw manager to init both acl mgr and router for all chains to be present
-			manager, err := Create(ifaceMock)
+			manager, err := Create(ifaceMock, iface.DefaultMTU)
 			t.Cleanup(func() {
 				require.NoError(t, manager.Close(nil))
 			})
@@ -125,7 +126,7 @@ func TestNftablesManager_RemoveNatRule(t *testing.T) {
 
 	for _, testCase := range test.RemoveRuleTestCases {
 		t.Run(testCase.Name, func(t *testing.T) {
-			manager, err := Create(ifaceMock)
+			manager, err := Create(ifaceMock, iface.DefaultMTU)
 			t.Cleanup(func() {
 				require.NoError(t, manager.Close(nil))
 			})
@@ -197,7 +198,7 @@ func TestRouter_AddRouteFiltering(t *testing.T) {
 
 	defer deleteWorkTable()
 
-	r, err := newRouter(workTable, ifaceMock)
+	r, err := newRouter(workTable, ifaceMock, iface.DefaultMTU)
 	require.NoError(t, err, "Failed to create router")
 	require.NoError(t, r.init(workTable))
 
@@ -364,7 +365,7 @@ func TestNftablesCreateIpSet(t *testing.T) {
 
 	defer deleteWorkTable()
 
-	r, err := newRouter(workTable, ifaceMock)
+	r, err := newRouter(workTable, ifaceMock, iface.DefaultMTU)
 	require.NoError(t, err, "Failed to create router")
 	require.NoError(t, r.init(workTable))
 

client/firewall/nftables/state_linux.go

@@ -3,6 +3,7 @@ package nftables
 import (
 	"fmt"
 
+	"github.com/netbirdio/netbird/client/iface"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 )
 
@@ -10,6 +11,7 @@ type InterfaceState struct {
 	NameStr       string         `json:"name"`
 	WGAddress     wgaddr.Address `json:"wg_address"`
 	UserspaceBind bool           `json:"userspace_bind"`
+	MTU           uint16         `json:"mtu"`
 }
 
 func (i *InterfaceState) Name() string {
@@ -33,7 +35,11 @@ func (s *ShutdownState) Name() string {
 }
 
 func (s *ShutdownState) Cleanup() error {
-	nft, err := Create(s.InterfaceState)
+	mtu := s.InterfaceState.MTU
+	if mtu == 0 {
+		mtu = iface.DefaultMTU
+	}
+	nft, err := Create(s.InterfaceState, mtu)
 	if err != nil {
 		return fmt.Errorf("create nftables manager: %w", err)
 	}

client/firewall/uspfilter/conntrack/common.go

@@ -22,6 +22,8 @@ type BaseConnTrack struct {
 	PacketsRx atomic.Uint64
 	BytesTx   atomic.Uint64
 	BytesRx   atomic.Uint64
+
+	DNATOrigPort atomic.Uint32
 }
 
 // these small methods will be inlined by the compiler

client/firewall/uspfilter/conntrack/tcp.go

@@ -157,7 +157,7 @@ func NewTCPTracker(timeout time.Duration, logger *nblog.Logger, flowLogger nftyp
 	return tracker
 }
 
-func (t *TCPTracker) updateIfExists(srcIP, dstIP netip.Addr, srcPort, dstPort uint16, flags uint8, direction nftypes.Direction, size int) (ConnKey, bool) {
+func (t *TCPTracker) updateIfExists(srcIP, dstIP netip.Addr, srcPort, dstPort uint16, flags uint8, direction nftypes.Direction, size int) (ConnKey, uint16, bool) {
 	key := ConnKey{
 		SrcIP:   srcIP,
 		DstIP:   dstIP,
@@ -171,28 +171,30 @@ func (t *TCPTracker) updateIfExists(srcIP, dstIP netip.Addr, srcPort, dstPort ui
 
 	if exists {
 		t.updateState(key, conn, flags, direction, size)
-		return key, true
+		return key, uint16(conn.DNATOrigPort.Load()), true
 	}
 
-	return key, false
+	return key, 0, false
 }
 
-// TrackOutbound records an outbound TCP connection
-func (t *TCPTracker) TrackOutbound(srcIP, dstIP netip.Addr, srcPort, dstPort uint16, flags uint8, size int) {
-	if _, exists := t.updateIfExists(dstIP, srcIP, dstPort, srcPort, flags, nftypes.Egress, size); !exists {
-		// if (inverted direction) conn is not tracked, track this direction
-		t.track(srcIP, dstIP, srcPort, dstPort, flags, nftypes.Egress, nil, size)
+// TrackOutbound records an outbound TCP connection and returns the original port if DNAT reversal is needed
+func (t *TCPTracker) TrackOutbound(srcIP, dstIP netip.Addr, srcPort, dstPort uint16, flags uint8, size int) uint16 {
+	if _, origPort, exists := t.updateIfExists(dstIP, srcIP, dstPort, srcPort, flags, nftypes.Egress, size); exists {
+		return origPort
 	}
+	// if (inverted direction) conn is not tracked, track this direction
+	t.track(srcIP, dstIP, srcPort, dstPort, flags, nftypes.Egress, nil, size, 0)
+	return 0
 }
 
 // TrackInbound processes an inbound TCP packet and updates connection state
-func (t *TCPTracker) TrackInbound(srcIP, dstIP netip.Addr, srcPort, dstPort uint16, flags uint8, ruleID []byte, size int) {
-	t.track(srcIP, dstIP, srcPort, dstPort, flags, nftypes.Ingress, ruleID, size)
+func (t *TCPTracker) TrackInbound(srcIP, dstIP netip.Addr, srcPort, dstPort uint16, flags uint8, ruleID []byte, size int, dnatOrigPort uint16) {
+	t.track(srcIP, dstIP, srcPort, dstPort, flags, nftypes.Ingress, ruleID, size, dnatOrigPort)
 }
 
 // track is the common implementation for tracking both inbound and outbound connections
-func (t *TCPTracker) track(srcIP, dstIP netip.Addr, srcPort, dstPort uint16, flags uint8, direction nftypes.Direction, ruleID []byte, size int) {
-	key, exists := t.updateIfExists(srcIP, dstIP, srcPort, dstPort, flags, direction, size)
+func (t *TCPTracker) track(srcIP, dstIP netip.Addr, srcPort, dstPort uint16, flags uint8, direction nftypes.Direction, ruleID []byte, size int, origPort uint16) {
+	key, _, exists := t.updateIfExists(srcIP, dstIP, srcPort, dstPort, flags, direction, size)
 	if exists || flags&TCPSyn == 0 {
 		return
 	}
@@ -210,8 +212,13 @@ func (t *TCPTracker) track(srcIP, dstIP netip.Addr, srcPort, dstPort uint16, fla
 
 	conn.tombstone.Store(false)
 	conn.state.Store(int32(TCPStateNew))
+	conn.DNATOrigPort.Store(uint32(origPort))
 
-	t.logger.Trace2("New %s TCP connection: %s", direction, key)
+	if origPort != 0 {
+		t.logger.Trace4("New %s TCP connection: %s (port DNAT %d -> %d)", direction, key, origPort, dstPort)
+	} else {
+		t.logger.Trace2("New %s TCP connection: %s", direction, key)
+	}
 	t.updateState(key, conn, flags, direction, size)
 
 	t.mutex.Lock()
@@ -449,6 +456,21 @@ func (t *TCPTracker) cleanup() {
 	}
 }
 
+// GetConnection safely retrieves a connection state
+func (t *TCPTracker) GetConnection(srcIP netip.Addr, srcPort uint16, dstIP netip.Addr, dstPort uint16) (*TCPConnTrack, bool) {
+	t.mutex.RLock()
+	defer t.mutex.RUnlock()
+
+	key := ConnKey{
+		SrcIP:   srcIP,
+		DstIP:   dstIP,
+		SrcPort: srcPort,
+		DstPort: dstPort,
+	}
+	conn, exists := t.connections[key]
+	return conn, exists
+}
+
 // Close stops the cleanup routine and releases resources
 func (t *TCPTracker) Close() {
 	t.tickerCancel()

client/firewall/uspfilter/conntrack/tcp_test.go

@@ -603,7 +603,7 @@ func TestTCPInboundInitiatedConnection(t *testing.T) {
 	serverPort := uint16(80)
 
 	// 1. Client sends SYN (we receive it as inbound)
-	tracker.TrackInbound(clientIP, serverIP, clientPort, serverPort, TCPSyn, nil, 100)
+	tracker.TrackInbound(clientIP, serverIP, clientPort, serverPort, TCPSyn, nil, 100, 0)
 
 	key := ConnKey{
 		SrcIP:   clientIP,
@@ -623,12 +623,12 @@ func TestTCPInboundInitiatedConnection(t *testing.T) {
 	tracker.TrackOutbound(serverIP, clientIP, serverPort, clientPort, TCPSyn|TCPAck, 100)
 
 	// 3. Client sends ACK to complete handshake
-	tracker.TrackInbound(clientIP, serverIP, clientPort, serverPort, TCPAck, nil, 100)
+	tracker.TrackInbound(clientIP, serverIP, clientPort, serverPort, TCPAck, nil, 100, 0)
 	require.Equal(t, TCPStateEstablished, conn.GetState(), "Connection should be ESTABLISHED after handshake completion")
 
 	// 4. Test data transfer
 	// Client sends data
-	tracker.TrackInbound(clientIP, serverIP, clientPort, serverPort, TCPPush|TCPAck, nil, 1000)
+	tracker.TrackInbound(clientIP, serverIP, clientPort, serverPort, TCPPush|TCPAck, nil, 1000, 0)
 
 	// Server sends ACK for data
 	tracker.TrackOutbound(serverIP, clientIP, serverPort, clientPort, TCPAck, 100)
@@ -637,7 +637,7 @@ func TestTCPInboundInitiatedConnection(t *testing.T) {
 	tracker.TrackOutbound(serverIP, clientIP, serverPort, clientPort, TCPPush|TCPAck, 1500)
 
 	// Client sends ACK for data
-	tracker.TrackInbound(clientIP, serverIP, clientPort, serverPort, TCPAck, nil, 100)
+	tracker.TrackInbound(clientIP, serverIP, clientPort, serverPort, TCPAck, nil, 100, 0)
 
 	// Verify state and counters
 	require.Equal(t, TCPStateEstablished, conn.GetState())

client/firewall/uspfilter/conntrack/udp.go

@@ -58,20 +58,23 @@ func NewUDPTracker(timeout time.Duration, logger *nblog.Logger, flowLogger nftyp
 	return tracker
 }
 
-// TrackOutbound records an outbound UDP connection
-func (t *UDPTracker) TrackOutbound(srcIP netip.Addr, dstIP netip.Addr, srcPort uint16, dstPort uint16, size int) {
-	if _, exists := t.updateIfExists(dstIP, srcIP, dstPort, srcPort, nftypes.Egress, size); !exists {
-		// if (inverted direction) conn is not tracked, track this direction
-		t.track(srcIP, dstIP, srcPort, dstPort, nftypes.Egress, nil, size)
+// TrackOutbound records an outbound UDP connection and returns the original port if DNAT reversal is needed
+func (t *UDPTracker) TrackOutbound(srcIP netip.Addr, dstIP netip.Addr, srcPort uint16, dstPort uint16, size int) uint16 {
+	_, origPort, exists := t.updateIfExists(dstIP, srcIP, dstPort, srcPort, nftypes.Egress, size)
+	if exists {
+		return origPort
 	}
+	// if (inverted direction) conn is not tracked, track this direction
+	t.track(srcIP, dstIP, srcPort, dstPort, nftypes.Egress, nil, size, 0)
+	return 0
 }
 
 // TrackInbound records an inbound UDP connection
-func (t *UDPTracker) TrackInbound(srcIP netip.Addr, dstIP netip.Addr, srcPort uint16, dstPort uint16, ruleID []byte, size int) {
-	t.track(srcIP, dstIP, srcPort, dstPort, nftypes.Ingress, ruleID, size)
+func (t *UDPTracker) TrackInbound(srcIP netip.Addr, dstIP netip.Addr, srcPort uint16, dstPort uint16, ruleID []byte, size int, dnatOrigPort uint16) {
+	t.track(srcIP, dstIP, srcPort, dstPort, nftypes.Ingress, ruleID, size, dnatOrigPort)
 }
 
-func (t *UDPTracker) updateIfExists(srcIP netip.Addr, dstIP netip.Addr, srcPort uint16, dstPort uint16, direction nftypes.Direction, size int) (ConnKey, bool) {
+func (t *UDPTracker) updateIfExists(srcIP netip.Addr, dstIP netip.Addr, srcPort uint16, dstPort uint16, direction nftypes.Direction, size int) (ConnKey, uint16, bool) {
 	key := ConnKey{
 		SrcIP:   srcIP,
 		DstIP:   dstIP,
@@ -86,15 +89,15 @@ func (t *UDPTracker) updateIfExists(srcIP netip.Addr, dstIP netip.Addr, srcPort
 	if exists {
 		conn.UpdateLastSeen()
 		conn.UpdateCounters(direction, size)
-		return key, true
+		return key, uint16(conn.DNATOrigPort.Load()), true
 	}
 
-	return key, false
+	return key, 0, false
 }
 
 // track is the common implementation for tracking both inbound and outbound connections
-func (t *UDPTracker) track(srcIP netip.Addr, dstIP netip.Addr, srcPort uint16, dstPort uint16, direction nftypes.Direction, ruleID []byte, size int) {
-	key, exists := t.updateIfExists(srcIP, dstIP, srcPort, dstPort, direction, size)
+func (t *UDPTracker) track(srcIP netip.Addr, dstIP netip.Addr, srcPort uint16, dstPort uint16, direction nftypes.Direction, ruleID []byte, size int, origPort uint16) {
+	key, _, exists := t.updateIfExists(srcIP, dstIP, srcPort, dstPort, direction, size)
 	if exists {
 		return
 	}
@@ -109,6 +112,7 @@ func (t *UDPTracker) track(srcIP netip.Addr, dstIP netip.Addr, srcPort uint16, d
 		SourcePort: srcPort,
 		DestPort:   dstPort,
 	}
+	conn.DNATOrigPort.Store(uint32(origPort))
 	conn.UpdateLastSeen()
 	conn.UpdateCounters(direction, size)
 
@@ -116,7 +120,11 @@ func (t *UDPTracker) track(srcIP netip.Addr, dstIP netip.Addr, srcPort uint16, d
 	t.connections[key] = conn
 	t.mutex.Unlock()
 
-	t.logger.Trace2("New %s UDP connection: %s", direction, key)
+	if origPort != 0 {
+		t.logger.Trace4("New %s UDP connection: %s (port DNAT %d -> %d)", direction, key, origPort, dstPort)
+	} else {
+		t.logger.Trace2("New %s UDP connection: %s", direction, key)
+	}
 	t.sendEvent(nftypes.TypeStart, conn, ruleID)
 }
 

client/firewall/uspfilter/filter.go

@@ -1,6 +1,7 @@
 package uspfilter
 
 import (
+	"encoding/binary"
 	"errors"
 	"fmt"
 	"net"
@@ -27,7 +28,12 @@ import (
 	"github.com/netbirdio/netbird/client/internal/statemanager"
 )
 
-const layerTypeAll = 0
+const (
+	layerTypeAll = 0
+
+	// ipTCPHeaderMinSize represents minimum IP (20) + TCP (20) header size for MSS calculation
+	ipTCPHeaderMinSize = 40
+)
 
 const (
 	// EnvDisableConntrack disables the stateful filter, replies to outbound traffic won't be allowed.
@@ -36,6 +42,9 @@ const (
 	// EnvDisableUserspaceRouting disables userspace routing, to-be-routed packets will be dropped.
 	EnvDisableUserspaceRouting = "NB_DISABLE_USERSPACE_ROUTING"
 
+	// EnvDisableMSSClamping disables TCP MSS clamping for forwarded traffic.
+	EnvDisableMSSClamping = "NB_DISABLE_MSS_CLAMPING"
+
 	// EnvForceUserspaceRouter forces userspace routing even if native routing is available.
 	EnvForceUserspaceRouter = "NB_FORCE_USERSPACE_ROUTER"
 
@@ -50,6 +59,12 @@ const (
 
 var errNatNotSupported = errors.New("nat not supported with userspace firewall")
 
+// serviceKey represents a protocol/port combination for netstack service registry
+type serviceKey struct {
+	protocol gopacket.LayerType
+	port     uint16
+}
+
 // RuleSet is a set of rules grouped by a string key
 type RuleSet map[string]PeerRule
 
@@ -109,6 +124,17 @@ type Manager struct {
 	dnatMappings map[netip.Addr]netip.Addr
 	dnatMutex    sync.RWMutex
 	dnatBiMap    *biDNATMap
+
+	portDNATEnabled atomic.Bool
+	portDNATRules   []portDNATRule
+	portDNATMutex   sync.RWMutex
+
+	netstackServices     map[serviceKey]struct{}
+	netstackServiceMutex sync.RWMutex
+
+	mtu             uint16
+	mssClampValue   uint16
+	mssClampEnabled bool
 }
 
 // decoder for packages
@@ -122,19 +148,21 @@ type decoder struct {
 	icmp6   layers.ICMPv6
 	decoded []gopacket.LayerType
 	parser  *gopacket.DecodingLayerParser
+
+	dnatOrigPort uint16
 }
 
 // Create userspace firewall manager constructor
-func Create(iface common.IFaceMapper, disableServerRoutes bool, flowLogger nftypes.FlowLogger) (*Manager, error) {
-	return create(iface, nil, disableServerRoutes, flowLogger)
+func Create(iface common.IFaceMapper, disableServerRoutes bool, flowLogger nftypes.FlowLogger, mtu uint16) (*Manager, error) {
+	return create(iface, nil, disableServerRoutes, flowLogger, mtu)
 }
 
-func CreateWithNativeFirewall(iface common.IFaceMapper, nativeFirewall firewall.Manager, disableServerRoutes bool, flowLogger nftypes.FlowLogger) (*Manager, error) {
+func CreateWithNativeFirewall(iface common.IFaceMapper, nativeFirewall firewall.Manager, disableServerRoutes bool, flowLogger nftypes.FlowLogger, mtu uint16) (*Manager, error) {
 	if nativeFirewall == nil {
 		return nil, errors.New("native firewall is nil")
 	}
 
-	mgr, err := create(iface, nativeFirewall, disableServerRoutes, flowLogger)
+	mgr, err := create(iface, nativeFirewall, disableServerRoutes, flowLogger, mtu)
 	if err != nil {
 		return nil, err
 	}
@@ -142,8 +170,8 @@ func CreateWithNativeFirewall(iface common.IFaceMapper, nativeFirewall firewall.
 	return mgr, nil
 }
 
-func parseCreateEnv() (bool, bool) {
-	var disableConntrack, enableLocalForwarding bool
+func parseCreateEnv() (bool, bool, bool) {
+	var disableConntrack, enableLocalForwarding, disableMSSClamping bool
 	var err error
 	if val := os.Getenv(EnvDisableConntrack); val != "" {
 		disableConntrack, err = strconv.ParseBool(val)
@@ -162,12 +190,18 @@ func parseCreateEnv() (bool, bool) {
 			log.Warnf("failed to parse %s: %v", EnvEnableLocalForwarding, err)
 		}
 	}
+	if val := os.Getenv(EnvDisableMSSClamping); val != "" {
+		disableMSSClamping, err = strconv.ParseBool(val)
+		if err != nil {
+			log.Warnf("failed to parse %s: %v", EnvDisableMSSClamping, err)
+		}
+	}
 
-	return disableConntrack, enableLocalForwarding
+	return disableConntrack, enableLocalForwarding, disableMSSClamping
 }
 
-func create(iface common.IFaceMapper, nativeFirewall firewall.Manager, disableServerRoutes bool, flowLogger nftypes.FlowLogger) (*Manager, error) {
-	disableConntrack, enableLocalForwarding := parseCreateEnv()
+func create(iface common.IFaceMapper, nativeFirewall firewall.Manager, disableServerRoutes bool, flowLogger nftypes.FlowLogger, mtu uint16) (*Manager, error) {
+	disableConntrack, enableLocalForwarding, disableMSSClamping := parseCreateEnv()
 
 	m := &Manager{
 		decoders: sync.Pool{
@@ -196,13 +230,19 @@ func create(iface common.IFaceMapper, nativeFirewall firewall.Manager, disableSe
 		netstack:            netstack.IsEnabled(),
 		localForwarding:     enableLocalForwarding,
 		dnatMappings:        make(map[netip.Addr]netip.Addr),
+		portDNATRules:       []portDNATRule{},
+		netstackServices:    make(map[serviceKey]struct{}),
+		mtu:                 mtu,
 	}
 	m.routingEnabled.Store(false)
 
+	if !disableMSSClamping {
+		m.mssClampEnabled = true
+		m.mssClampValue = mtu - ipTCPHeaderMinSize
+	}
 	if err := m.localipmanager.UpdateLocalIPs(iface); err != nil {
 		return nil, fmt.Errorf("update local IPs: %w", err)
 	}
-
 	if disableConntrack {
 		log.Info("conntrack is disabled")
 	} else {
@@ -210,14 +250,11 @@ func create(iface common.IFaceMapper, nativeFirewall firewall.Manager, disableSe
 		m.icmpTracker = conntrack.NewICMPTracker(conntrack.DefaultICMPTimeout, m.logger, flowLogger)
 		m.tcpTracker = conntrack.NewTCPTracker(conntrack.DefaultTCPTimeout, m.logger, flowLogger)
 	}
-
-	// netstack needs the forwarder for local traffic
 	if m.netstack && m.localForwarding {
 		if err := m.initForwarder(); err != nil {
 			log.Errorf("failed to initialize forwarder: %v", err)
 		}
 	}
-
 	if err := iface.SetFilter(m); err != nil {
 		return nil, fmt.Errorf("set filter: %w", err)
 	}
@@ -320,7 +357,7 @@ func (m *Manager) initForwarder() error {
 		return errors.New("forwarding not supported")
 	}
 
-	forwarder, err := forwarder.New(m.wgIface, m.logger, m.flowLogger, m.netstack)
+	forwarder, err := forwarder.New(m.wgIface, m.logger, m.flowLogger, m.netstack, m.mtu)
 	if err != nil {
 		m.routingEnabled.Store(false)
 		return fmt.Errorf("create forwarder: %w", err)
@@ -626,11 +663,20 @@ func (m *Manager) filterOutbound(packetData []byte, size int) bool {
 		return false
 	}
 
-	if d.decoded[1] == layers.LayerTypeUDP && m.udpHooksDrop(uint16(d.udp.DstPort), dstIP, packetData) {
-		return true
+	switch d.decoded[1] {
+	case layers.LayerTypeUDP:
+		if m.udpHooksDrop(uint16(d.udp.DstPort), dstIP, packetData) {
+			return true
+		}
+	case layers.LayerTypeTCP:
+		// Clamp MSS on all TCP SYN packets, including those from local IPs.
+		// SNATed routed traffic may appear as local IP but still requires clamping.
+		if m.mssClampEnabled {
+			m.clampTCPMSS(packetData, d)
+		}
 	}
 
-	m.trackOutbound(d, srcIP, dstIP, size)
+	m.trackOutbound(d, srcIP, dstIP, packetData, size)
 	m.translateOutboundDNAT(packetData, d)
 
 	return false
@@ -674,14 +720,117 @@ func getTCPFlags(tcp *layers.TCP) uint8 {
 	return flags
 }
 
-func (m *Manager) trackOutbound(d *decoder, srcIP, dstIP netip.Addr, size int) {
+// clampTCPMSS clamps the TCP MSS option in SYN and SYN-ACK packets to prevent fragmentation.
+// Both sides advertise their MSS during connection establishment, so we need to clamp both.
+func (m *Manager) clampTCPMSS(packetData []byte, d *decoder) bool {
+	if !d.tcp.SYN {
+		return false
+	}
+	if len(d.tcp.Options) == 0 {
+		return false
+	}
+
+	mssOptionIndex := -1
+	var currentMSS uint16
+	for i, opt := range d.tcp.Options {
+		if opt.OptionType == layers.TCPOptionKindMSS && len(opt.OptionData) == 2 {
+			currentMSS = binary.BigEndian.Uint16(opt.OptionData)
+			if currentMSS > m.mssClampValue {
+				mssOptionIndex = i
+				break
+			}
+		}
+	}
+
+	if mssOptionIndex == -1 {
+		return false
+	}
+
+	ipHeaderSize := int(d.ip4.IHL) * 4
+	if ipHeaderSize < 20 {
+		return false
+	}
+
+	if !m.updateMSSOption(packetData, d, mssOptionIndex, ipHeaderSize) {
+		return false
+	}
+
+	m.logger.Trace2("Clamped TCP MSS from %d to %d", currentMSS, m.mssClampValue)
+	return true
+}
+
+func (m *Manager) updateMSSOption(packetData []byte, d *decoder, mssOptionIndex, ipHeaderSize int) bool {
+	tcpHeaderStart := ipHeaderSize
+	tcpOptionsStart := tcpHeaderStart + 20
+
+	optOffset := tcpOptionsStart
+	for j := 0; j < mssOptionIndex; j++ {
+		switch d.tcp.Options[j].OptionType {
+		case layers.TCPOptionKindEndList, layers.TCPOptionKindNop:
+			optOffset++
+		default:
+			optOffset += 2 + len(d.tcp.Options[j].OptionData)
+		}
+	}
+
+	mssValueOffset := optOffset + 2
+	binary.BigEndian.PutUint16(packetData[mssValueOffset:mssValueOffset+2], m.mssClampValue)
+
+	m.recalculateTCPChecksum(packetData, d, tcpHeaderStart)
+	return true
+}
+
+func (m *Manager) recalculateTCPChecksum(packetData []byte, d *decoder, tcpHeaderStart int) {
+	tcpLayer := packetData[tcpHeaderStart:]
+	tcpLength := len(packetData) - tcpHeaderStart
+
+	tcpLayer[16] = 0
+	tcpLayer[17] = 0
+
+	var pseudoSum uint32
+	pseudoSum += uint32(d.ip4.SrcIP[0])<<8 | uint32(d.ip4.SrcIP[1])
+	pseudoSum += uint32(d.ip4.SrcIP[2])<<8 | uint32(d.ip4.SrcIP[3])
+	pseudoSum += uint32(d.ip4.DstIP[0])<<8 | uint32(d.ip4.DstIP[1])
+	pseudoSum += uint32(d.ip4.DstIP[2])<<8 | uint32(d.ip4.DstIP[3])
+	pseudoSum += uint32(d.ip4.Protocol)
+	pseudoSum += uint32(tcpLength)
+
+	var sum uint32 = pseudoSum
+	for i := 0; i < tcpLength-1; i += 2 {
+		sum += uint32(tcpLayer[i])<<8 | uint32(tcpLayer[i+1])
+	}
+	if tcpLength%2 == 1 {
+		sum += uint32(tcpLayer[tcpLength-1]) << 8
+	}
+
+	for sum > 0xFFFF {
+		sum = (sum & 0xFFFF) + (sum >> 16)
+	}
+
+	checksum := ^uint16(sum)
+	binary.BigEndian.PutUint16(tcpLayer[16:18], checksum)
+}
+
+func (m *Manager) trackOutbound(d *decoder, srcIP, dstIP netip.Addr, packetData []byte, size int) {
 	transport := d.decoded[1]
 	switch transport {
 	case layers.LayerTypeUDP:
-		m.udpTracker.TrackOutbound(srcIP, dstIP, uint16(d.udp.SrcPort), uint16(d.udp.DstPort), size)
+		origPort := m.udpTracker.TrackOutbound(srcIP, dstIP, uint16(d.udp.SrcPort), uint16(d.udp.DstPort), size)
+		if origPort == 0 {
+			break
+		}
+		if err := m.rewriteUDPPort(packetData, d, origPort, sourcePortOffset); err != nil {
+			m.logger.Error1("failed to rewrite UDP port: %v", err)
+		}
 	case layers.LayerTypeTCP:
 		flags := getTCPFlags(&d.tcp)
-		m.tcpTracker.TrackOutbound(srcIP, dstIP, uint16(d.tcp.SrcPort), uint16(d.tcp.DstPort), flags, size)
+		origPort := m.tcpTracker.TrackOutbound(srcIP, dstIP, uint16(d.tcp.SrcPort), uint16(d.tcp.DstPort), flags, size)
+		if origPort == 0 {
+			break
+		}
+		if err := m.rewriteTCPPort(packetData, d, origPort, sourcePortOffset); err != nil {
+			m.logger.Error1("failed to rewrite TCP port: %v", err)
+		}
 	case layers.LayerTypeICMPv4:
 		m.icmpTracker.TrackOutbound(srcIP, dstIP, d.icmp4.Id, d.icmp4.TypeCode, d.icmp4.Payload, size)
 	}
@@ -691,13 +840,15 @@ func (m *Manager) trackInbound(d *decoder, srcIP, dstIP netip.Addr, ruleID []byt
 	transport := d.decoded[1]
 	switch transport {
 	case layers.LayerTypeUDP:
-		m.udpTracker.TrackInbound(srcIP, dstIP, uint16(d.udp.SrcPort), uint16(d.udp.DstPort), ruleID, size)
+		m.udpTracker.TrackInbound(srcIP, dstIP, uint16(d.udp.SrcPort), uint16(d.udp.DstPort), ruleID, size, d.dnatOrigPort)
 	case layers.LayerTypeTCP:
 		flags := getTCPFlags(&d.tcp)
-		m.tcpTracker.TrackInbound(srcIP, dstIP, uint16(d.tcp.SrcPort), uint16(d.tcp.DstPort), flags, ruleID, size)
+		m.tcpTracker.TrackInbound(srcIP, dstIP, uint16(d.tcp.SrcPort), uint16(d.tcp.DstPort), flags, ruleID, size, d.dnatOrigPort)
 	case layers.LayerTypeICMPv4:
 		m.icmpTracker.TrackInbound(srcIP, dstIP, d.icmp4.Id, d.icmp4.TypeCode, ruleID, d.icmp4.Payload, size)
 	}
+
+	d.dnatOrigPort = 0
 }
 
 // udpHooksDrop checks if any UDP hooks should drop the packet
@@ -759,10 +910,20 @@ func (m *Manager) filterInbound(packetData []byte, size int) bool {
 		return false
 	}
 
+	// TODO: optimize port DNAT by caching matched rules in conntrack
+	if translated := m.translateInboundPortDNAT(packetData, d, srcIP, dstIP); translated {
+		// Re-decode after port DNAT translation to update port information
+		if err := d.parser.DecodeLayers(packetData, &d.decoded); err != nil {
+			m.logger.Error1("failed to re-decode packet after port DNAT: %v", err)
+			return true
+		}
+		srcIP, dstIP = m.extractIPs(d)
+	}
+
 	if translated := m.translateInboundReverse(packetData, d); translated {
 		// Re-decode after translation to get original addresses
 		if err := d.parser.DecodeLayers(packetData, &d.decoded); err != nil {
-			m.logger.Error1("Failed to re-decode packet after reverse DNAT: %v", err)
+			m.logger.Error1("failed to re-decode packet after reverse DNAT: %v", err)
 			return true
 		}
 		srcIP, dstIP = m.extractIPs(d)
@@ -807,9 +968,7 @@ func (m *Manager) handleLocalTraffic(d *decoder, srcIP, dstIP netip.Addr, packet
 		return true
 	}
 
-	// If requested we pass local traffic to internal interfaces to the forwarder.
-	// netstack doesn't have an interface to forward packets to the native stack so we always need to use the forwarder.
-	if m.localForwarding && (m.netstack || dstIP != m.wgIface.Address().IP) {
+	if m.shouldForward(d, dstIP) {
 		return m.handleForwardedLocalTraffic(packetData)
 	}
 
@@ -1243,3 +1402,86 @@ func (m *Manager) DisableRouting() error {
 
 	return nil
 }
+
+// RegisterNetstackService registers a service as listening on the netstack for the given protocol and port
+func (m *Manager) RegisterNetstackService(protocol nftypes.Protocol, port uint16) {
+	m.netstackServiceMutex.Lock()
+	defer m.netstackServiceMutex.Unlock()
+	layerType := m.protocolToLayerType(protocol)
+	key := serviceKey{protocol: layerType, port: port}
+	m.netstackServices[key] = struct{}{}
+	m.logger.Debug3("RegisterNetstackService: registered %s:%d (layerType=%s)", protocol, port, layerType)
+	m.logger.Debug1("RegisterNetstackService: current registry size: %d", len(m.netstackServices))
+}
+
+// UnregisterNetstackService removes a service from the netstack registry
+func (m *Manager) UnregisterNetstackService(protocol nftypes.Protocol, port uint16) {
+	m.netstackServiceMutex.Lock()
+	defer m.netstackServiceMutex.Unlock()
+	layerType := m.protocolToLayerType(protocol)
+	key := serviceKey{protocol: layerType, port: port}
+	delete(m.netstackServices, key)
+	m.logger.Debug2("Unregistered netstack service on protocol %s port %d", protocol, port)
+}
+
+// protocolToLayerType converts nftypes.Protocol to gopacket.LayerType for internal use
+func (m *Manager) protocolToLayerType(protocol nftypes.Protocol) gopacket.LayerType {
+	switch protocol {
+	case nftypes.TCP:
+		return layers.LayerTypeTCP
+	case nftypes.UDP:
+		return layers.LayerTypeUDP
+	case nftypes.ICMP:
+		return layers.LayerTypeICMPv4
+	default:
+		return gopacket.LayerType(0) // Invalid/unknown
+	}
+}
+
+// shouldForward determines if a packet should be forwarded to the forwarder.
+// The forwarder handles routing packets to the native OS network stack.
+// Returns true if packet should go to the forwarder, false if it should go to netstack listeners or the native stack directly.
+func (m *Manager) shouldForward(d *decoder, dstIP netip.Addr) bool {
+	// not enabled, never forward
+	if !m.localForwarding {
+		return false
+	}
+
+	// netstack always needs to forward because it's lacking a native interface
+	// exception for registered netstack services, those should go to netstack listeners
+	if m.netstack {
+		return !m.hasMatchingNetstackService(d)
+	}
+
+	// traffic to our other local interfaces (not NetBird IP) - always forward
+	if dstIP != m.wgIface.Address().IP {
+		return true
+	}
+
+	// traffic to our NetBird IP, not netstack mode - send to netstack listeners
+	return false
+}
+
+// hasMatchingNetstackService checks if there's a registered netstack service for this packet
+func (m *Manager) hasMatchingNetstackService(d *decoder) bool {
+	if len(d.decoded) < 2 {
+		return false
+	}
+
+	var dstPort uint16
+	switch d.decoded[1] {
+	case layers.LayerTypeTCP:
+		dstPort = uint16(d.tcp.DstPort)
+	case layers.LayerTypeUDP:
+		dstPort = uint16(d.udp.DstPort)
+	default:
+		return false
+	}
+
+	key := serviceKey{protocol: d.decoded[1], port: dstPort}
+	m.netstackServiceMutex.RLock()
+	_, exists := m.netstackServices[key]
+	m.netstackServiceMutex.RUnlock()
+
+	return exists
+}

client/firewall/uspfilter/filter_bench_test.go

@@ -17,6 +17,7 @@ import (
 
 	fw "github.com/netbirdio/netbird/client/firewall/manager"
 	"github.com/netbirdio/netbird/client/firewall/uspfilter/conntrack"
+	"github.com/netbirdio/netbird/client/iface"
 	"github.com/netbirdio/netbird/client/iface/device"
 )
 
@@ -169,7 +170,7 @@ func BenchmarkCoreFiltering(b *testing.B) {
 				// Create manager and basic setup
 				manager, _ := Create(&IFaceMock{
 					SetFilterFunc: func(device.PacketFilter) error { return nil },
-				}, false, flowLogger)
+				}, false, flowLogger, iface.DefaultMTU)
 				defer b.Cleanup(func() {
 					require.NoError(b, manager.Close(nil))
 				})
@@ -209,7 +210,7 @@ func BenchmarkStateScaling(b *testing.B) {
 		b.Run(fmt.Sprintf("conns_%d", count), func(b *testing.B) {
 			manager, _ := Create(&IFaceMock{
 				SetFilterFunc: func(device.PacketFilter) error { return nil },
-			}, false, flowLogger)
+			}, false, flowLogger, iface.DefaultMTU)
 			b.Cleanup(func() {
 				require.NoError(b, manager.Close(nil))
 			})
@@ -252,7 +253,7 @@ func BenchmarkEstablishmentOverhead(b *testing.B) {
 		b.Run(sc.name, func(b *testing.B) {
 			manager, _ := Create(&IFaceMock{
 				SetFilterFunc: func(device.PacketFilter) error { return nil },
-			}, false, flowLogger)
+			}, false, flowLogger, iface.DefaultMTU)
 			b.Cleanup(func() {
 				require.NoError(b, manager.Close(nil))
 			})
@@ -410,7 +411,7 @@ func BenchmarkRoutedNetworkReturn(b *testing.B) {
 		b.Run(sc.name, func(b *testing.B) {
 			manager, _ := Create(&IFaceMock{
 				SetFilterFunc: func(device.PacketFilter) error { return nil },
-			}, false, flowLogger)
+			}, false, flowLogger, iface.DefaultMTU)
 			b.Cleanup(func() {
 				require.NoError(b, manager.Close(nil))
 			})
@@ -537,7 +538,7 @@ func BenchmarkLongLivedConnections(b *testing.B) {
 
 			manager, _ := Create(&IFaceMock{
 				SetFilterFunc: func(device.PacketFilter) error { return nil },
-			}, false, flowLogger)
+			}, false, flowLogger, iface.DefaultMTU)
 			defer b.Cleanup(func() {
 				require.NoError(b, manager.Close(nil))
 			})
@@ -620,7 +621,7 @@ func BenchmarkShortLivedConnections(b *testing.B) {
 
 			manager, _ := Create(&IFaceMock{
 				SetFilterFunc: func(device.PacketFilter) error { return nil },
-			}, false, flowLogger)
+			}, false, flowLogger, iface.DefaultMTU)
 			defer b.Cleanup(func() {
 				require.NoError(b, manager.Close(nil))
 			})
@@ -731,7 +732,7 @@ func BenchmarkParallelLongLivedConnections(b *testing.B) {
 
 			manager, _ := Create(&IFaceMock{
 				SetFilterFunc: func(device.PacketFilter) error { return nil },
-			}, false, flowLogger)
+			}, false, flowLogger, iface.DefaultMTU)
 			defer b.Cleanup(func() {
 				require.NoError(b, manager.Close(nil))
 			})
@@ -811,7 +812,7 @@ func BenchmarkParallelShortLivedConnections(b *testing.B) {
 
 			manager, _ := Create(&IFaceMock{
 				SetFilterFunc: func(device.PacketFilter) error { return nil },
-			}, false, flowLogger)
+			}, false, flowLogger, iface.DefaultMTU)
 			defer b.Cleanup(func() {
 				require.NoError(b, manager.Close(nil))
 			})
@@ -896,38 +897,6 @@ func BenchmarkParallelShortLivedConnections(b *testing.B) {
 	}
 }
 
-// generateTCPPacketWithFlags creates a TCP packet with specific flags
-func generateTCPPacketWithFlags(b *testing.B, srcIP, dstIP net.IP, srcPort, dstPort, flags uint16) []byte {
-	b.Helper()
-
-	ipv4 := &layers.IPv4{
-		TTL:      64,
-		Version:  4,
-		SrcIP:    srcIP,
-		DstIP:    dstIP,
-		Protocol: layers.IPProtocolTCP,
-	}
-
-	tcp := &layers.TCP{
-		SrcPort: layers.TCPPort(srcPort),
-		DstPort: layers.TCPPort(dstPort),
-	}
-
-	// Set TCP flags
-	tcp.SYN = (flags & uint16(conntrack.TCPSyn)) != 0
-	tcp.ACK = (flags & uint16(conntrack.TCPAck)) != 0
-	tcp.PSH = (flags & uint16(conntrack.TCPPush)) != 0
-	tcp.RST = (flags & uint16(conntrack.TCPRst)) != 0
-	tcp.FIN = (flags & uint16(conntrack.TCPFin)) != 0
-
-	require.NoError(b, tcp.SetNetworkLayerForChecksum(ipv4))
-
-	buf := gopacket.NewSerializeBuffer()
-	opts := gopacket.SerializeOptions{ComputeChecksums: true, FixLengths: true}
-	require.NoError(b, gopacket.SerializeLayers(buf, opts, ipv4, tcp, gopacket.Payload("test")))
-	return buf.Bytes()
-}
-
 func BenchmarkRouteACLs(b *testing.B) {
 	manager := setupRoutedManager(b, "10.10.0.100/16")
 
@@ -990,3 +959,231 @@ func BenchmarkRouteACLs(b *testing.B) {
 		}
 	}
 }
+
+// BenchmarkMSSClamping benchmarks the MSS clamping impact on filterOutbound.
+// This shows the overhead difference between the common case (non-SYN packets, fast path)
+// and the rare case (SYN packets that need clamping, expensive path).
+func BenchmarkMSSClamping(b *testing.B) {
+	scenarios := []struct {
+		name        string
+		description string
+		genPacket   func(*testing.B, net.IP, net.IP) []byte
+		frequency   string
+	}{
+		{
+			name:        "syn_needs_clamp",
+			description: "SYN packet needing MSS clamping",
+			genPacket: func(b *testing.B, src, dst net.IP) []byte {
+				return generateSYNPacketWithMSS(b, src, dst, 12345, 80, 1460)
+			},
+			frequency: "~0.1% of traffic - EXPENSIVE",
+		},
+		{
+			name:        "syn_no_clamp_needed",
+			description: "SYN packet with already-small MSS",
+			genPacket: func(b *testing.B, src, dst net.IP) []byte {
+				return generateSYNPacketWithMSS(b, src, dst, 12345, 80, 1200)
+			},
+			frequency: "~0.05% of traffic",
+		},
+		{
+			name:        "tcp_ack",
+			description: "Non-SYN TCP packet (ACK, data transfer)",
+			genPacket: func(b *testing.B, src, dst net.IP) []byte {
+				return generateTCPPacketWithFlags(b, src, dst, 12345, 80, uint16(conntrack.TCPAck))
+			},
+			frequency: "~60-70% of traffic - FAST PATH",
+		},
+		{
+			name:        "tcp_psh_ack",
+			description: "TCP data packet (PSH+ACK)",
+			genPacket: func(b *testing.B, src, dst net.IP) []byte {
+				return generateTCPPacketWithFlags(b, src, dst, 12345, 80, uint16(conntrack.TCPPush|conntrack.TCPAck))
+			},
+			frequency: "~10-20% of traffic - FAST PATH",
+		},
+		{
+			name:        "udp",
+			description: "UDP packet",
+			genPacket: func(b *testing.B, src, dst net.IP) []byte {
+				return generatePacket(b, src, dst, 12345, 80, layers.IPProtocolUDP)
+			},
+			frequency: "~20-30% of traffic - FAST PATH",
+		},
+	}
+
+	for _, sc := range scenarios {
+		b.Run(sc.name, func(b *testing.B) {
+			manager, err := Create(&IFaceMock{
+				SetFilterFunc: func(device.PacketFilter) error { return nil },
+			}, false, flowLogger, iface.DefaultMTU)
+			require.NoError(b, err)
+			defer func() {
+				require.NoError(b, manager.Close(nil))
+			}()
+
+			manager.mssClampEnabled = true
+			manager.mssClampValue = 1240
+
+			srcIP := net.ParseIP("100.64.0.2")
+			dstIP := net.ParseIP("8.8.8.8")
+			packet := sc.genPacket(b, srcIP, dstIP)
+
+			b.ReportAllocs()
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				manager.filterOutbound(packet, len(packet))
+			}
+		})
+	}
+}
+
+// BenchmarkMSSClampingOverhead compares overhead of MSS clamping enabled vs disabled
+// for the common case (non-SYN TCP packets).
+func BenchmarkMSSClampingOverhead(b *testing.B) {
+	scenarios := []struct {
+		name      string
+		enabled   bool
+		genPacket func(*testing.B, net.IP, net.IP) []byte
+	}{
+		{
+			name:    "disabled_tcp_ack",
+			enabled: false,
+			genPacket: func(b *testing.B, src, dst net.IP) []byte {
+				return generateTCPPacketWithFlags(b, src, dst, 12345, 80, uint16(conntrack.TCPAck))
+			},
+		},
+		{
+			name:    "enabled_tcp_ack",
+			enabled: true,
+			genPacket: func(b *testing.B, src, dst net.IP) []byte {
+				return generateTCPPacketWithFlags(b, src, dst, 12345, 80, uint16(conntrack.TCPAck))
+			},
+		},
+		{
+			name:    "disabled_syn_needs_clamp",
+			enabled: false,
+			genPacket: func(b *testing.B, src, dst net.IP) []byte {
+				return generateSYNPacketWithMSS(b, src, dst, 12345, 80, 1460)
+			},
+		},
+		{
+			name:    "enabled_syn_needs_clamp",
+			enabled: true,
+			genPacket: func(b *testing.B, src, dst net.IP) []byte {
+				return generateSYNPacketWithMSS(b, src, dst, 12345, 80, 1460)
+			},
+		},
+	}
+
+	for _, sc := range scenarios {
+		b.Run(sc.name, func(b *testing.B) {
+			manager, err := Create(&IFaceMock{
+				SetFilterFunc: func(device.PacketFilter) error { return nil },
+			}, false, flowLogger, iface.DefaultMTU)
+			require.NoError(b, err)
+			defer func() {
+				require.NoError(b, manager.Close(nil))
+			}()
+
+			manager.mssClampEnabled = sc.enabled
+			if sc.enabled {
+				manager.mssClampValue = 1240
+			}
+
+			srcIP := net.ParseIP("100.64.0.2")
+			dstIP := net.ParseIP("8.8.8.8")
+			packet := sc.genPacket(b, srcIP, dstIP)
+
+			b.ReportAllocs()
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				manager.filterOutbound(packet, len(packet))
+			}
+		})
+	}
+}
+
+// BenchmarkMSSClampingMemory measures memory allocations for common vs rare cases
+func BenchmarkMSSClampingMemory(b *testing.B) {
+	scenarios := []struct {
+		name      string
+		genPacket func(*testing.B, net.IP, net.IP) []byte
+	}{
+		{
+			name: "tcp_ack_fast_path",
+			genPacket: func(b *testing.B, src, dst net.IP) []byte {
+				return generateTCPPacketWithFlags(b, src, dst, 12345, 80, uint16(conntrack.TCPAck))
+			},
+		},
+		{
+			name: "syn_needs_clamp",
+			genPacket: func(b *testing.B, src, dst net.IP) []byte {
+				return generateSYNPacketWithMSS(b, src, dst, 12345, 80, 1460)
+			},
+		},
+		{
+			name: "udp_fast_path",
+			genPacket: func(b *testing.B, src, dst net.IP) []byte {
+				return generatePacket(b, src, dst, 12345, 80, layers.IPProtocolUDP)
+			},
+		},
+	}
+
+	for _, sc := range scenarios {
+		b.Run(sc.name, func(b *testing.B) {
+			manager, err := Create(&IFaceMock{
+				SetFilterFunc: func(device.PacketFilter) error { return nil },
+			}, false, flowLogger, iface.DefaultMTU)
+			require.NoError(b, err)
+			defer func() {
+				require.NoError(b, manager.Close(nil))
+			}()
+
+			manager.mssClampEnabled = true
+			manager.mssClampValue = 1240
+
+			srcIP := net.ParseIP("100.64.0.2")
+			dstIP := net.ParseIP("8.8.8.8")
+			packet := sc.genPacket(b, srcIP, dstIP)
+
+			b.ReportAllocs()
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				manager.filterOutbound(packet, len(packet))
+			}
+		})
+	}
+}
+
+func generateSYNPacketNoMSS(b *testing.B, srcIP, dstIP net.IP, srcPort, dstPort uint16) []byte {
+	b.Helper()
+
+	ip := &layers.IPv4{
+		Version:  4,
+		IHL:      5,
+		TTL:      64,
+		Protocol: layers.IPProtocolTCP,
+		SrcIP:    srcIP,
+		DstIP:    dstIP,
+	}
+
+	tcp := &layers.TCP{
+		SrcPort: layers.TCPPort(srcPort),
+		DstPort: layers.TCPPort(dstPort),
+		SYN:     true,
+		Seq:     1000,
+		Window:  65535,
+	}
+
+	require.NoError(b, tcp.SetNetworkLayerForChecksum(ip))
+
+	buf := gopacket.NewSerializeBuffer()
+	opts := gopacket.SerializeOptions{
+		FixLengths:       true,
+		ComputeChecksums: true,
+	}
+
+	require.NoError(b, gopacket.SerializeLayers(buf, opts, ip, tcp, gopacket.Payload([]byte{})))
+	return buf.Bytes()
+}

client/firewall/uspfilter/filter_filter_test.go

@@ -12,6 +12,7 @@ import (
 	wgdevice "golang.zx2c4.com/wireguard/device"
 
 	fw "github.com/netbirdio/netbird/client/firewall/manager"
+	"github.com/netbirdio/netbird/client/iface"
 	"github.com/netbirdio/netbird/client/iface/device"
 	"github.com/netbirdio/netbird/client/iface/mocks"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
@@ -31,7 +32,7 @@ func TestPeerACLFiltering(t *testing.T) {
 		},
 	}
 
-	manager, err := Create(ifaceMock, false, flowLogger)
+	manager, err := Create(ifaceMock, false, flowLogger, iface.DefaultMTU)
 	require.NoError(t, err)
 	require.NotNil(t, manager)
 
@@ -616,7 +617,7 @@ func setupRoutedManager(tb testing.TB, network string) *Manager {
 		},
 	}
 
-	manager, err := Create(ifaceMock, false, flowLogger)
+	manager, err := Create(ifaceMock, false, flowLogger, iface.DefaultMTU)
 	require.NoError(tb, err)
 	require.NoError(tb, manager.EnableRouting())
 	require.NotNil(tb, manager)
@@ -1462,7 +1463,7 @@ func TestRouteACLSet(t *testing.T) {
 		},
 	}
 
-	manager, err := Create(ifaceMock, false, flowLogger)
+	manager, err := Create(ifaceMock, false, flowLogger, iface.DefaultMTU)
 	require.NoError(t, err)
 	t.Cleanup(func() {
 		require.NoError(t, manager.Close(nil))

client/firewall/uspfilter/filter_test.go

@@ -1,6 +1,7 @@
 package uspfilter
 
 import (
+	"encoding/binary"
 	"fmt"
 	"net"
 	"net/netip"
@@ -17,6 +18,7 @@ import (
 	fw "github.com/netbirdio/netbird/client/firewall/manager"
 	"github.com/netbirdio/netbird/client/firewall/uspfilter/conntrack"
 	"github.com/netbirdio/netbird/client/firewall/uspfilter/log"
+	nbiface "github.com/netbirdio/netbird/client/iface"
 	"github.com/netbirdio/netbird/client/iface/device"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 	"github.com/netbirdio/netbird/client/internal/netflow"
@@ -66,7 +68,7 @@ func TestManagerCreate(t *testing.T) {
 		SetFilterFunc: func(device.PacketFilter) error { return nil },
 	}
 
-	m, err := Create(ifaceMock, false, flowLogger)
+	m, err := Create(ifaceMock, false, flowLogger, nbiface.DefaultMTU)
 	if err != nil {
 		t.Errorf("failed to create Manager: %v", err)
 		return
@@ -86,7 +88,7 @@ func TestManagerAddPeerFiltering(t *testing.T) {
 		},
 	}
 
-	m, err := Create(ifaceMock, false, flowLogger)
+	m, err := Create(ifaceMock, false, flowLogger, nbiface.DefaultMTU)
 	if err != nil {
 		t.Errorf("failed to create Manager: %v", err)
 		return
@@ -119,7 +121,7 @@ func TestManagerDeleteRule(t *testing.T) {
 		SetFilterFunc: func(device.PacketFilter) error { return nil },
 	}
 
-	m, err := Create(ifaceMock, false, flowLogger)
+	m, err := Create(ifaceMock, false, flowLogger, nbiface.DefaultMTU)
 	if err != nil {
 		t.Errorf("failed to create Manager: %v", err)
 		return
@@ -215,7 +217,7 @@ func TestAddUDPPacketHook(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			manager, err := Create(&IFaceMock{
 				SetFilterFunc: func(device.PacketFilter) error { return nil },
-			}, false, flowLogger)
+			}, false, flowLogger, nbiface.DefaultMTU)
 			require.NoError(t, err)
 
 			manager.AddUDPPacketHook(tt.in, tt.ip, tt.dPort, tt.hook)
@@ -265,7 +267,7 @@ func TestManagerReset(t *testing.T) {
 		SetFilterFunc: func(device.PacketFilter) error { return nil },
 	}
 
-	m, err := Create(ifaceMock, false, flowLogger)
+	m, err := Create(ifaceMock, false, flowLogger, nbiface.DefaultMTU)
 	if err != nil {
 		t.Errorf("failed to create Manager: %v", err)
 		return
@@ -304,7 +306,7 @@ func TestNotMatchByIP(t *testing.T) {
 		},
 	}
 
-	m, err := Create(ifaceMock, false, flowLogger)
+	m, err := Create(ifaceMock, false, flowLogger, nbiface.DefaultMTU)
 	if err != nil {
 		t.Errorf("failed to create Manager: %v", err)
 		return
@@ -367,7 +369,7 @@ func TestRemovePacketHook(t *testing.T) {
 	}
 
 	// creating manager instance
-	manager, err := Create(iface, false, flowLogger)
+	manager, err := Create(iface, false, flowLogger, nbiface.DefaultMTU)
 	if err != nil {
 		t.Fatalf("Failed to create Manager: %s", err)
 	}
@@ -413,7 +415,7 @@ func TestRemovePacketHook(t *testing.T) {
 func TestProcessOutgoingHooks(t *testing.T) {
 	manager, err := Create(&IFaceMock{
 		SetFilterFunc: func(device.PacketFilter) error { return nil },
-	}, false, flowLogger)
+	}, false, flowLogger, nbiface.DefaultMTU)
 	require.NoError(t, err)
 
 	manager.udpTracker.Close()
@@ -495,7 +497,7 @@ func TestUSPFilterCreatePerformance(t *testing.T) {
 			ifaceMock := &IFaceMock{
 				SetFilterFunc: func(device.PacketFilter) error { return nil },
 			}
-			manager, err := Create(ifaceMock, false, flowLogger)
+			manager, err := Create(ifaceMock, false, flowLogger, nbiface.DefaultMTU)
 			require.NoError(t, err)
 			time.Sleep(time.Second)
 
@@ -522,7 +524,7 @@ func TestUSPFilterCreatePerformance(t *testing.T) {
 func TestStatefulFirewall_UDPTracking(t *testing.T) {
 	manager, err := Create(&IFaceMock{
 		SetFilterFunc: func(device.PacketFilter) error { return nil },
-	}, false, flowLogger)
+	}, false, flowLogger, nbiface.DefaultMTU)
 	require.NoError(t, err)
 
 	manager.udpTracker.Close() // Close the existing tracker
@@ -729,7 +731,7 @@ func TestUpdateSetMerge(t *testing.T) {
 		SetFilterFunc: func(device.PacketFilter) error { return nil },
 	}
 
-	manager, err := Create(ifaceMock, false, flowLogger)
+	manager, err := Create(ifaceMock, false, flowLogger, nbiface.DefaultMTU)
 	require.NoError(t, err)
 	t.Cleanup(func() {
 		require.NoError(t, manager.Close(nil))
@@ -815,7 +817,7 @@ func TestUpdateSetDeduplication(t *testing.T) {
 		SetFilterFunc: func(device.PacketFilter) error { return nil },
 	}
 
-	manager, err := Create(ifaceMock, false, flowLogger)
+	manager, err := Create(ifaceMock, false, flowLogger, nbiface.DefaultMTU)
 	require.NoError(t, err)
 	t.Cleanup(func() {
 		require.NoError(t, manager.Close(nil))
@@ -923,3 +925,192 @@ func TestUpdateSetDeduplication(t *testing.T) {
 		require.Equal(t, tc.expected, isAllowed, tc.desc)
 	}
 }
+
+func TestMSSClamping(t *testing.T) {
+	ifaceMock := &IFaceMock{
+		SetFilterFunc: func(device.PacketFilter) error { return nil },
+		AddressFunc: func() wgaddr.Address {
+			return wgaddr.Address{
+				IP:      netip.MustParseAddr("100.10.0.100"),
+				Network: netip.MustParsePrefix("100.10.0.0/16"),
+			}
+		},
+	}
+
+	manager, err := Create(ifaceMock, false, flowLogger, 1280)
+	require.NoError(t, err)
+	defer func() {
+		require.NoError(t, manager.Close(nil))
+	}()
+
+	require.True(t, manager.mssClampEnabled, "MSS clamping should be enabled by default")
+	expectedMSSValue := uint16(1280 - ipTCPHeaderMinSize)
+	require.Equal(t, expectedMSSValue, manager.mssClampValue, "MSS clamp value should be MTU - 40")
+
+	err = manager.UpdateLocalIPs()
+	require.NoError(t, err)
+
+	srcIP := net.ParseIP("100.10.0.2")
+	dstIP := net.ParseIP("8.8.8.8")
+
+	t.Run("SYN packet with high MSS gets clamped", func(t *testing.T) {
+		highMSS := uint16(1460)
+		packet := generateSYNPacketWithMSS(t, srcIP, dstIP, 12345, 80, highMSS)
+
+		manager.filterOutbound(packet, len(packet))
+
+		d := parsePacket(t, packet)
+		require.Len(t, d.tcp.Options, 1, "Should have MSS option")
+		require.Equal(t, uint8(layers.TCPOptionKindMSS), uint8(d.tcp.Options[0].OptionType))
+		actualMSS := binary.BigEndian.Uint16(d.tcp.Options[0].OptionData)
+		require.Equal(t, expectedMSSValue, actualMSS, "MSS should be clamped to MTU - 40")
+	})
+
+	t.Run("SYN packet with low MSS unchanged", func(t *testing.T) {
+		lowMSS := uint16(1200)
+		packet := generateSYNPacketWithMSS(t, srcIP, dstIP, 12345, 80, lowMSS)
+
+		manager.filterOutbound(packet, len(packet))
+
+		d := parsePacket(t, packet)
+		require.Len(t, d.tcp.Options, 1, "Should have MSS option")
+		actualMSS := binary.BigEndian.Uint16(d.tcp.Options[0].OptionData)
+		require.Equal(t, lowMSS, actualMSS, "Low MSS should not be modified")
+	})
+
+	t.Run("SYN-ACK packet gets clamped", func(t *testing.T) {
+		highMSS := uint16(1460)
+		packet := generateSYNACKPacketWithMSS(t, srcIP, dstIP, 12345, 80, highMSS)
+
+		manager.filterOutbound(packet, len(packet))
+
+		d := parsePacket(t, packet)
+		require.Len(t, d.tcp.Options, 1, "Should have MSS option")
+		actualMSS := binary.BigEndian.Uint16(d.tcp.Options[0].OptionData)
+		require.Equal(t, expectedMSSValue, actualMSS, "MSS in SYN-ACK should be clamped")
+	})
+
+	t.Run("Non-SYN packet unchanged", func(t *testing.T) {
+		packet := generateTCPPacketWithFlags(t, srcIP, dstIP, 12345, 80, uint16(conntrack.TCPAck))
+
+		manager.filterOutbound(packet, len(packet))
+
+		d := parsePacket(t, packet)
+		require.Empty(t, d.tcp.Options, "ACK packet should have no options")
+	})
+}
+
+func generateSYNPacketWithMSS(tb testing.TB, srcIP, dstIP net.IP, srcPort, dstPort uint16, mss uint16) []byte {
+	tb.Helper()
+
+	ipLayer := &layers.IPv4{
+		Version:  4,
+		TTL:      64,
+		Protocol: layers.IPProtocolTCP,
+		SrcIP:    srcIP,
+		DstIP:    dstIP,
+	}
+
+	tcpLayer := &layers.TCP{
+		SrcPort: layers.TCPPort(srcPort),
+		DstPort: layers.TCPPort(dstPort),
+		SYN:     true,
+		Window:  65535,
+		Options: []layers.TCPOption{
+			{
+				OptionType:   layers.TCPOptionKindMSS,
+				OptionLength: 4,
+				OptionData:   binary.BigEndian.AppendUint16(nil, mss),
+			},
+		},
+	}
+	err := tcpLayer.SetNetworkLayerForChecksum(ipLayer)
+	require.NoError(tb, err)
+
+	buf := gopacket.NewSerializeBuffer()
+	opts := gopacket.SerializeOptions{ComputeChecksums: true, FixLengths: true}
+	err = gopacket.SerializeLayers(buf, opts, ipLayer, tcpLayer, gopacket.Payload([]byte{}))
+	require.NoError(tb, err)
+
+	return buf.Bytes()
+}
+
+func generateSYNACKPacketWithMSS(tb testing.TB, srcIP, dstIP net.IP, srcPort, dstPort uint16, mss uint16) []byte {
+	tb.Helper()
+
+	ipLayer := &layers.IPv4{
+		Version:  4,
+		TTL:      64,
+		Protocol: layers.IPProtocolTCP,
+		SrcIP:    srcIP,
+		DstIP:    dstIP,
+	}
+
+	tcpLayer := &layers.TCP{
+		SrcPort: layers.TCPPort(srcPort),
+		DstPort: layers.TCPPort(dstPort),
+		SYN:     true,
+		ACK:     true,
+		Window:  65535,
+		Options: []layers.TCPOption{
+			{
+				OptionType:   layers.TCPOptionKindMSS,
+				OptionLength: 4,
+				OptionData:   binary.BigEndian.AppendUint16(nil, mss),
+			},
+		},
+	}
+	err := tcpLayer.SetNetworkLayerForChecksum(ipLayer)
+	require.NoError(tb, err)
+
+	buf := gopacket.NewSerializeBuffer()
+	opts := gopacket.SerializeOptions{ComputeChecksums: true, FixLengths: true}
+	err = gopacket.SerializeLayers(buf, opts, ipLayer, tcpLayer, gopacket.Payload([]byte{}))
+	require.NoError(tb, err)
+
+	return buf.Bytes()
+}
+
+func generateTCPPacketWithFlags(tb testing.TB, srcIP, dstIP net.IP, srcPort, dstPort uint16, flags uint16) []byte {
+	tb.Helper()
+
+	ipLayer := &layers.IPv4{
+		Version:  4,
+		TTL:      64,
+		Protocol: layers.IPProtocolTCP,
+		SrcIP:    srcIP,
+		DstIP:    dstIP,
+	}
+
+	tcpLayer := &layers.TCP{
+		SrcPort: layers.TCPPort(srcPort),
+		DstPort: layers.TCPPort(dstPort),
+		Window:  65535,
+	}
+
+	if flags&uint16(conntrack.TCPSyn) != 0 {
+		tcpLayer.SYN = true
+	}
+	if flags&uint16(conntrack.TCPAck) != 0 {
+		tcpLayer.ACK = true
+	}
+	if flags&uint16(conntrack.TCPFin) != 0 {
+		tcpLayer.FIN = true
+	}
+	if flags&uint16(conntrack.TCPRst) != 0 {
+		tcpLayer.RST = true
+	}
+	if flags&uint16(conntrack.TCPPush) != 0 {
+		tcpLayer.PSH = true
+	}
+
+	err := tcpLayer.SetNetworkLayerForChecksum(ipLayer)
+	require.NoError(tb, err)
+
+	buf := gopacket.NewSerializeBuffer()
+	opts := gopacket.SerializeOptions{ComputeChecksums: true, FixLengths: true}
+	err = gopacket.SerializeLayers(buf, opts, ipLayer, tcpLayer, gopacket.Payload([]byte{}))
+	require.NoError(tb, err)
+
+	return buf.Bytes()
+}

client/firewall/uspfilter/forwarder/forwarder.go

@@ -45,7 +45,7 @@ type Forwarder struct {
 	netstack     bool
 }
 
-func New(iface common.IFaceMapper, logger *nblog.Logger, flowLogger nftypes.FlowLogger, netstack bool) (*Forwarder, error) {
+func New(iface common.IFaceMapper, logger *nblog.Logger, flowLogger nftypes.FlowLogger, netstack bool, mtu uint16) (*Forwarder, error) {
 	s := stack.New(stack.Options{
 		NetworkProtocols: []stack.NetworkProtocolFactory{ipv4.NewProtocol},
 		TransportProtocols: []stack.TransportProtocolFactory{
@@ -56,10 +56,6 @@ func New(iface common.IFaceMapper, logger *nblog.Logger, flowLogger nftypes.Flow
 		HandleLocal: false,
 	})
 
-	mtu, err := iface.GetDevice().MTU()
-	if err != nil {
-		return nil, fmt.Errorf("get MTU: %w", err)
-	}
 	nicID := tcpip.NICID(1)
 	endpoint := &endpoint{
 		logger: logger,
@@ -68,7 +64,7 @@ func New(iface common.IFaceMapper, logger *nblog.Logger, flowLogger nftypes.Flow
 	}
 
 	if err := s.CreateNIC(nicID, endpoint); err != nil {
-		return nil, fmt.Errorf("failed to create NIC: %v", err)
+		return nil, fmt.Errorf("create NIC: %v", err)
 	}
 
 	protoAddr := tcpip.ProtocolAddress{

client/firewall/uspfilter/forwarder/udp.go

@@ -49,7 +49,7 @@ type idleConn struct {
 	conn *udpPacketConn
 }
 
-func newUDPForwarder(mtu int, logger *nblog.Logger, flowLogger nftypes.FlowLogger) *udpForwarder {
+func newUDPForwarder(mtu uint16, logger *nblog.Logger, flowLogger nftypes.FlowLogger) *udpForwarder {
 	ctx, cancel := context.WithCancel(context.Background())
 	f := &udpForwarder{
 		logger:     logger,

client/firewall/uspfilter/log/log.go

@@ -50,6 +50,8 @@ type logMessage struct {
 	arg4   any
 	arg5   any
 	arg6   any
+	arg7   any
+	arg8   any
 }
 
 // Logger is a high-performance, non-blocking logger
@@ -94,7 +96,6 @@ func (l *Logger) SetLevel(level Level) {
 	log.Debugf("Set uspfilter logger loglevel to %v", levelStrings[level])
 }
 
-
 func (l *Logger) Error(format string) {
 	if l.level.Load() >= uint32(LevelError) {
 		select {
@@ -185,6 +186,15 @@ func (l *Logger) Debug2(format string, arg1, arg2 any) {
 	}
 }
 
+func (l *Logger) Debug3(format string, arg1, arg2, arg3 any) {
+	if l.level.Load() >= uint32(LevelDebug) {
+		select {
+		case l.msgChannel <- logMessage{level: LevelDebug, format: format, arg1: arg1, arg2: arg2, arg3: arg3}:
+		default:
+		}
+	}
+}
+
 func (l *Logger) Trace1(format string, arg1 any) {
 	if l.level.Load() >= uint32(LevelTrace) {
 		select {
@@ -239,6 +249,16 @@ func (l *Logger) Trace6(format string, arg1, arg2, arg3, arg4, arg5, arg6 any) {
 	}
 }
 
+// Trace8 logs a trace message with 8 arguments (8 placeholder in format string)
+func (l *Logger) Trace8(format string, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8 any) {
+	if l.level.Load() >= uint32(LevelTrace) {
+		select {
+		case l.msgChannel <- logMessage{level: LevelTrace, format: format, arg1: arg1, arg2: arg2, arg3: arg3, arg4: arg4, arg5: arg5, arg6: arg6, arg7: arg7, arg8: arg8}:
+		default:
+		}
+	}
+}
+
 func (l *Logger) formatMessage(buf *[]byte, msg logMessage) {
 	*buf = (*buf)[:0]
 	*buf = time.Now().AppendFormat(*buf, "2006-01-02T15:04:05-07:00")
@@ -260,6 +280,12 @@ func (l *Logger) formatMessage(buf *[]byte, msg logMessage) {
 						argCount++
 						if msg.arg6 != nil {
 							argCount++
+							if msg.arg7 != nil {
+								argCount++
+								if msg.arg8 != nil {
+									argCount++
+								}
+							}
 						}
 					}
 				}
@@ -283,6 +309,10 @@ func (l *Logger) formatMessage(buf *[]byte, msg logMessage) {
 		formatted = fmt.Sprintf(msg.format, msg.arg1, msg.arg2, msg.arg3, msg.arg4, msg.arg5)
 	case 6:
 		formatted = fmt.Sprintf(msg.format, msg.arg1, msg.arg2, msg.arg3, msg.arg4, msg.arg5, msg.arg6)
+	case 7:
+		formatted = fmt.Sprintf(msg.format, msg.arg1, msg.arg2, msg.arg3, msg.arg4, msg.arg5, msg.arg6, msg.arg7)
+	case 8:
+		formatted = fmt.Sprintf(msg.format, msg.arg1, msg.arg2, msg.arg3, msg.arg4, msg.arg5, msg.arg6, msg.arg7, msg.arg8)
 	}
 
 	*buf = append(*buf, formatted...)
@@ -390,4 +420,4 @@ func (l *Logger) Stop(ctx context.Context) error {
 	case <-done:
 		return nil
 	}
-}
+}

client/firewall/uspfilter/nat.go

@@ -5,7 +5,9 @@ import (
 	"errors"
 	"fmt"
 	"net/netip"
+	"slices"
 
+	"github.com/google/gopacket"
 	"github.com/google/gopacket/layers"
 
 	firewall "github.com/netbirdio/netbird/client/firewall/manager"
@@ -13,6 +15,21 @@ import (
 
 var ErrIPv4Only = errors.New("only IPv4 is supported for DNAT")
 
+var (
+	errInvalidIPHeaderLength = errors.New("invalid IP header length")
+)
+
+const (
+	// Port offsets in TCP/UDP headers
+	sourcePortOffset      = 0
+	destinationPortOffset = 2
+
+	// IP address offsets in IPv4 header
+	sourceIPOffset      = 12
+	destinationIPOffset = 16
+)
+
+// ipv4Checksum calculates IPv4 header checksum.
 func ipv4Checksum(header []byte) uint16 {
 	if len(header) < 20 {
 		return 0
@@ -52,6 +69,7 @@ func ipv4Checksum(header []byte) uint16 {
 	return ^uint16(sum)
 }
 
+// icmpChecksum calculates ICMP checksum.
 func icmpChecksum(data []byte) uint16 {
 	var sum1, sum2, sum3, sum4 uint32
 	i := 0
@@ -89,11 +107,21 @@ func icmpChecksum(data []byte) uint16 {
 	return ^uint16(sum)
 }
 
+// biDNATMap maintains bidirectional DNAT mappings.
 type biDNATMap struct {
 	forward map[netip.Addr]netip.Addr
 	reverse map[netip.Addr]netip.Addr
 }
 
+// portDNATRule represents a port-specific DNAT rule.
+type portDNATRule struct {
+	protocol   gopacket.LayerType
+	origPort   uint16
+	targetPort uint16
+	targetIP   netip.Addr
+}
+
+// newBiDNATMap creates a new bidirectional DNAT mapping structure.
 func newBiDNATMap() *biDNATMap {
 	return &biDNATMap{
 		forward: make(map[netip.Addr]netip.Addr),
@@ -101,11 +129,13 @@ func newBiDNATMap() *biDNATMap {
 	}
 }
 
+// set adds a bidirectional DNAT mapping between original and translated addresses.
 func (b *biDNATMap) set(original, translated netip.Addr) {
 	b.forward[original] = translated
 	b.reverse[translated] = original
 }
 
+// delete removes a bidirectional DNAT mapping for the given original address.
 func (b *biDNATMap) delete(original netip.Addr) {
 	if translated, exists := b.forward[original]; exists {
 		delete(b.forward, original)
@@ -113,19 +143,25 @@ func (b *biDNATMap) delete(original netip.Addr) {
 	}
 }
 
+// getTranslated returns the translated address for a given original address.
 func (b *biDNATMap) getTranslated(original netip.Addr) (netip.Addr, bool) {
 	translated, exists := b.forward[original]
 	return translated, exists
 }
 
+// getOriginal returns the original address for a given translated address.
 func (b *biDNATMap) getOriginal(translated netip.Addr) (netip.Addr, bool) {
 	original, exists := b.reverse[translated]
 	return original, exists
 }
 
+// AddInternalDNATMapping adds a 1:1 IP address mapping for internal DNAT translation.
 func (m *Manager) AddInternalDNATMapping(originalAddr, translatedAddr netip.Addr) error {
-	if !originalAddr.IsValid() || !translatedAddr.IsValid() {
-		return fmt.Errorf("invalid IP addresses")
+	if !originalAddr.IsValid() {
+		return fmt.Errorf("invalid original IP address")
+	}
+	if !translatedAddr.IsValid() {
+		return fmt.Errorf("invalid translated IP address")
 	}
 
 	if m.localipmanager.IsLocalIP(translatedAddr) {
@@ -135,7 +171,6 @@ func (m *Manager) AddInternalDNATMapping(originalAddr, translatedAddr netip.Addr
 	m.dnatMutex.Lock()
 	defer m.dnatMutex.Unlock()
 
-	// Initialize both maps together if either is nil
 	if m.dnatMappings == nil || m.dnatBiMap == nil {
 		m.dnatMappings = make(map[netip.Addr]netip.Addr)
 		m.dnatBiMap = newBiDNATMap()
@@ -151,7 +186,7 @@ func (m *Manager) AddInternalDNATMapping(originalAddr, translatedAddr netip.Addr
 	return nil
 }
 
-// RemoveInternalDNATMapping removes a 1:1 IP address mapping
+// RemoveInternalDNATMapping removes a 1:1 IP address mapping.
 func (m *Manager) RemoveInternalDNATMapping(originalAddr netip.Addr) error {
 	m.dnatMutex.Lock()
 	defer m.dnatMutex.Unlock()
@@ -169,7 +204,7 @@ func (m *Manager) RemoveInternalDNATMapping(originalAddr netip.Addr) error {
 	return nil
 }
 
-// getDNATTranslation returns the translated address if a mapping exists
+// getDNATTranslation returns the translated address if a mapping exists.
 func (m *Manager) getDNATTranslation(addr netip.Addr) (netip.Addr, bool) {
 	if !m.dnatEnabled.Load() {
 		return addr, false
@@ -181,7 +216,7 @@ func (m *Manager) getDNATTranslation(addr netip.Addr) (netip.Addr, bool) {
 	return translated, exists
 }
 
-// findReverseDNATMapping finds original address for return traffic
+// findReverseDNATMapping finds original address for return traffic.
 func (m *Manager) findReverseDNATMapping(translatedAddr netip.Addr) (netip.Addr, bool) {
 	if !m.dnatEnabled.Load() {
 		return translatedAddr, false
@@ -193,16 +228,12 @@ func (m *Manager) findReverseDNATMapping(translatedAddr netip.Addr) (netip.Addr,
 	return original, exists
 }
 
-// translateOutboundDNAT applies DNAT translation to outbound packets
+// translateOutboundDNAT applies DNAT translation to outbound packets.
 func (m *Manager) translateOutboundDNAT(packetData []byte, d *decoder) bool {
 	if !m.dnatEnabled.Load() {
 		return false
 	}
 
-	if len(packetData) < 20 || d.decoded[0] != layers.LayerTypeIPv4 {
-		return false
-	}
-
 	dstIP := netip.AddrFrom4([4]byte{packetData[16], packetData[17], packetData[18], packetData[19]})
 
 	translatedIP, exists := m.getDNATTranslation(dstIP)
@@ -210,8 +241,8 @@ func (m *Manager) translateOutboundDNAT(packetData []byte, d *decoder) bool {
 		return false
 	}
 
-	if err := m.rewritePacketDestination(packetData, d, translatedIP); err != nil {
-		m.logger.Error1("Failed to rewrite packet destination: %v", err)
+	if err := m.rewritePacketIP(packetData, d, translatedIP, destinationIPOffset); err != nil {
+		m.logger.Error1("failed to rewrite packet destination: %v", err)
 		return false
 	}
 
@@ -219,16 +250,12 @@ func (m *Manager) translateOutboundDNAT(packetData []byte, d *decoder) bool {
 	return true
 }
 
-// translateInboundReverse applies reverse DNAT to inbound return traffic
+// translateInboundReverse applies reverse DNAT to inbound return traffic.
 func (m *Manager) translateInboundReverse(packetData []byte, d *decoder) bool {
 	if !m.dnatEnabled.Load() {
 		return false
 	}
 
-	if len(packetData) < 20 || d.decoded[0] != layers.LayerTypeIPv4 {
-		return false
-	}
-
 	srcIP := netip.AddrFrom4([4]byte{packetData[12], packetData[13], packetData[14], packetData[15]})
 
 	originalIP, exists := m.findReverseDNATMapping(srcIP)
@@ -236,8 +263,8 @@ func (m *Manager) translateInboundReverse(packetData []byte, d *decoder) bool {
 		return false
 	}
 
-	if err := m.rewritePacketSource(packetData, d, originalIP); err != nil {
-		m.logger.Error1("Failed to rewrite packet source: %v", err)
+	if err := m.rewritePacketIP(packetData, d, originalIP, sourceIPOffset); err != nil {
+		m.logger.Error1("failed to rewrite packet source: %v", err)
 		return false
 	}
 
@@ -245,21 +272,21 @@ func (m *Manager) translateInboundReverse(packetData []byte, d *decoder) bool {
 	return true
 }
 
-// rewritePacketDestination replaces destination IP in the packet
-func (m *Manager) rewritePacketDestination(packetData []byte, d *decoder, newIP netip.Addr) error {
-	if len(packetData) < 20 || d.decoded[0] != layers.LayerTypeIPv4 || !newIP.Is4() {
+// rewritePacketIP replaces an IP address (source or destination) in the packet and updates checksums.
+func (m *Manager) rewritePacketIP(packetData []byte, d *decoder, newIP netip.Addr, ipOffset int) error {
+	if !newIP.Is4() {
 		return ErrIPv4Only
 	}
 
-	var oldDst [4]byte
-	copy(oldDst[:], packetData[16:20])
-	newDst := newIP.As4()
+	var oldIP [4]byte
+	copy(oldIP[:], packetData[ipOffset:ipOffset+4])
+	newIPBytes := newIP.As4()
 
-	copy(packetData[16:20], newDst[:])
+	copy(packetData[ipOffset:ipOffset+4], newIPBytes[:])
 
 	ipHeaderLen := int(d.ip4.IHL) * 4
 	if ipHeaderLen < 20 || ipHeaderLen > len(packetData) {
-		return fmt.Errorf("invalid IP header length")
+		return errInvalidIPHeaderLength
 	}
 
 	binary.BigEndian.PutUint16(packetData[10:12], 0)
@@ -269,44 +296,9 @@ func (m *Manager) rewritePacketDestination(packetData []byte, d *decoder, newIP
 	if len(d.decoded) > 1 {
 		switch d.decoded[1] {
 		case layers.LayerTypeTCP:
-			m.updateTCPChecksum(packetData, ipHeaderLen, oldDst[:], newDst[:])
+			m.updateTCPChecksum(packetData, ipHeaderLen, oldIP[:], newIPBytes[:])
 		case layers.LayerTypeUDP:
-			m.updateUDPChecksum(packetData, ipHeaderLen, oldDst[:], newDst[:])
-		case layers.LayerTypeICMPv4:
-			m.updateICMPChecksum(packetData, ipHeaderLen)
-		}
-	}
-
-	return nil
-}
-
-// rewritePacketSource replaces the source IP address in the packet
-func (m *Manager) rewritePacketSource(packetData []byte, d *decoder, newIP netip.Addr) error {
-	if len(packetData) < 20 || d.decoded[0] != layers.LayerTypeIPv4 || !newIP.Is4() {
-		return ErrIPv4Only
-	}
-
-	var oldSrc [4]byte
-	copy(oldSrc[:], packetData[12:16])
-	newSrc := newIP.As4()
-
-	copy(packetData[12:16], newSrc[:])
-
-	ipHeaderLen := int(d.ip4.IHL) * 4
-	if ipHeaderLen < 20 || ipHeaderLen > len(packetData) {
-		return fmt.Errorf("invalid IP header length")
-	}
-
-	binary.BigEndian.PutUint16(packetData[10:12], 0)
-	ipChecksum := ipv4Checksum(packetData[:ipHeaderLen])
-	binary.BigEndian.PutUint16(packetData[10:12], ipChecksum)
-
-	if len(d.decoded) > 1 {
-		switch d.decoded[1] {
-		case layers.LayerTypeTCP:
-			m.updateTCPChecksum(packetData, ipHeaderLen, oldSrc[:], newSrc[:])
-		case layers.LayerTypeUDP:
-			m.updateUDPChecksum(packetData, ipHeaderLen, oldSrc[:], newSrc[:])
+			m.updateUDPChecksum(packetData, ipHeaderLen, oldIP[:], newIPBytes[:])
 		case layers.LayerTypeICMPv4:
 			m.updateICMPChecksum(packetData, ipHeaderLen)
 		}
@@ -315,6 +307,7 @@ func (m *Manager) rewritePacketSource(packetData []byte, d *decoder, newIP netip
 	return nil
 }
 
+// updateTCPChecksum updates TCP checksum after IP address change per RFC 1624.
 func (m *Manager) updateTCPChecksum(packetData []byte, ipHeaderLen int, oldIP, newIP []byte) {
 	tcpStart := ipHeaderLen
 	if len(packetData) < tcpStart+18 {
@@ -327,6 +320,7 @@ func (m *Manager) updateTCPChecksum(packetData []byte, ipHeaderLen int, oldIP, n
 	binary.BigEndian.PutUint16(packetData[checksumOffset:checksumOffset+2], newChecksum)
 }
 
+// updateUDPChecksum updates UDP checksum after IP address change per RFC 1624.
 func (m *Manager) updateUDPChecksum(packetData []byte, ipHeaderLen int, oldIP, newIP []byte) {
 	udpStart := ipHeaderLen
 	if len(packetData) < udpStart+8 {
@@ -344,6 +338,7 @@ func (m *Manager) updateUDPChecksum(packetData []byte, ipHeaderLen int, oldIP, n
 	binary.BigEndian.PutUint16(packetData[checksumOffset:checksumOffset+2], newChecksum)
 }
 
+// updateICMPChecksum recalculates ICMP checksum after packet modification.
 func (m *Manager) updateICMPChecksum(packetData []byte, ipHeaderLen int) {
 	icmpStart := ipHeaderLen
 	if len(packetData) < icmpStart+8 {
@@ -356,7 +351,7 @@ func (m *Manager) updateICMPChecksum(packetData []byte, ipHeaderLen int) {
 	binary.BigEndian.PutUint16(icmpData[2:4], checksum)
 }
 
-// incrementalUpdate performs incremental checksum update per RFC 1624
+// incrementalUpdate performs incremental checksum update per RFC 1624.
 func incrementalUpdate(oldChecksum uint16, oldBytes, newBytes []byte) uint16 {
 	sum := uint32(^oldChecksum)
 
@@ -391,7 +386,7 @@ func incrementalUpdate(oldChecksum uint16, oldBytes, newBytes []byte) uint16 {
 	return ^uint16(sum)
 }
 
-// AddDNATRule adds a DNAT rule (delegates to native firewall for port forwarding)
+// AddDNATRule adds outbound DNAT rule for forwarding external traffic to NetBird network.
 func (m *Manager) AddDNATRule(rule firewall.ForwardRule) (firewall.Rule, error) {
 	if m.nativeFirewall == nil {
 		return nil, errNatNotSupported
@@ -399,10 +394,184 @@ func (m *Manager) AddDNATRule(rule firewall.ForwardRule) (firewall.Rule, error)
 	return m.nativeFirewall.AddDNATRule(rule)
 }
 
-// DeleteDNATRule deletes a DNAT rule (delegates to native firewall)
+// DeleteDNATRule deletes outbound DNAT rule.
 func (m *Manager) DeleteDNATRule(rule firewall.Rule) error {
 	if m.nativeFirewall == nil {
 		return errNatNotSupported
 	}
 	return m.nativeFirewall.DeleteDNATRule(rule)
 }
+
+// addPortRedirection adds a port redirection rule.
+func (m *Manager) addPortRedirection(targetIP netip.Addr, protocol gopacket.LayerType, sourcePort, targetPort uint16) error {
+	m.portDNATMutex.Lock()
+	defer m.portDNATMutex.Unlock()
+
+	rule := portDNATRule{
+		protocol:   protocol,
+		origPort:   sourcePort,
+		targetPort: targetPort,
+		targetIP:   targetIP,
+	}
+
+	m.portDNATRules = append(m.portDNATRules, rule)
+	m.portDNATEnabled.Store(true)
+
+	return nil
+}
+
+// AddInboundDNAT adds an inbound DNAT rule redirecting traffic from NetBird peers to local services.
+func (m *Manager) AddInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	var layerType gopacket.LayerType
+	switch protocol {
+	case firewall.ProtocolTCP:
+		layerType = layers.LayerTypeTCP
+	case firewall.ProtocolUDP:
+		layerType = layers.LayerTypeUDP
+	default:
+		return fmt.Errorf("unsupported protocol: %s", protocol)
+	}
+
+	return m.addPortRedirection(localAddr, layerType, sourcePort, targetPort)
+}
+
+// removePortRedirection removes a port redirection rule.
+func (m *Manager) removePortRedirection(targetIP netip.Addr, protocol gopacket.LayerType, sourcePort, targetPort uint16) error {
+	m.portDNATMutex.Lock()
+	defer m.portDNATMutex.Unlock()
+
+	m.portDNATRules = slices.DeleteFunc(m.portDNATRules, func(rule portDNATRule) bool {
+		return rule.protocol == protocol && rule.origPort == sourcePort && rule.targetPort == targetPort && rule.targetIP.Compare(targetIP) == 0
+	})
+
+	if len(m.portDNATRules) == 0 {
+		m.portDNATEnabled.Store(false)
+	}
+
+	return nil
+}
+
+// RemoveInboundDNAT removes an inbound DNAT rule.
+func (m *Manager) RemoveInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	var layerType gopacket.LayerType
+	switch protocol {
+	case firewall.ProtocolTCP:
+		layerType = layers.LayerTypeTCP
+	case firewall.ProtocolUDP:
+		layerType = layers.LayerTypeUDP
+	default:
+		return fmt.Errorf("unsupported protocol: %s", protocol)
+	}
+
+	return m.removePortRedirection(localAddr, layerType, sourcePort, targetPort)
+}
+
+// translateInboundPortDNAT applies port-specific DNAT translation to inbound packets.
+func (m *Manager) translateInboundPortDNAT(packetData []byte, d *decoder, srcIP, dstIP netip.Addr) bool {
+	if !m.portDNATEnabled.Load() {
+		return false
+	}
+
+	switch d.decoded[1] {
+	case layers.LayerTypeTCP:
+		dstPort := uint16(d.tcp.DstPort)
+		return m.applyPortRule(packetData, d, srcIP, dstIP, dstPort, layers.LayerTypeTCP, m.rewriteTCPPort)
+	case layers.LayerTypeUDP:
+		dstPort := uint16(d.udp.DstPort)
+		return m.applyPortRule(packetData, d, netip.Addr{}, dstIP, dstPort, layers.LayerTypeUDP, m.rewriteUDPPort)
+	default:
+		return false
+	}
+}
+
+type portRewriteFunc func(packetData []byte, d *decoder, newPort uint16, portOffset int) error
+
+func (m *Manager) applyPortRule(packetData []byte, d *decoder, srcIP, dstIP netip.Addr, port uint16, protocol gopacket.LayerType, rewriteFn portRewriteFunc) bool {
+	m.portDNATMutex.RLock()
+	defer m.portDNATMutex.RUnlock()
+
+	for _, rule := range m.portDNATRules {
+		if rule.protocol != protocol || rule.targetIP.Compare(dstIP) != 0 {
+			continue
+		}
+
+		if rule.targetPort == port && rule.targetIP.Compare(srcIP) == 0 {
+			return false
+		}
+
+		if rule.origPort != port {
+			continue
+		}
+
+		if err := rewriteFn(packetData, d, rule.targetPort, destinationPortOffset); err != nil {
+			m.logger.Error1("failed to rewrite port: %v", err)
+			return false
+		}
+		d.dnatOrigPort = rule.origPort
+		return true
+	}
+	return false
+}
+
+// rewriteTCPPort rewrites a TCP port (source or destination) and updates checksum.
+func (m *Manager) rewriteTCPPort(packetData []byte, d *decoder, newPort uint16, portOffset int) error {
+	ipHeaderLen := int(d.ip4.IHL) * 4
+	if ipHeaderLen < 20 || ipHeaderLen > len(packetData) {
+		return errInvalidIPHeaderLength
+	}
+
+	tcpStart := ipHeaderLen
+	if len(packetData) < tcpStart+4 {
+		return fmt.Errorf("packet too short for TCP header")
+	}
+
+	portStart := tcpStart + portOffset
+	oldPort := binary.BigEndian.Uint16(packetData[portStart : portStart+2])
+	binary.BigEndian.PutUint16(packetData[portStart:portStart+2], newPort)
+
+	if len(packetData) >= tcpStart+18 {
+		checksumOffset := tcpStart + 16
+		oldChecksum := binary.BigEndian.Uint16(packetData[checksumOffset : checksumOffset+2])
+
+		var oldPortBytes, newPortBytes [2]byte
+		binary.BigEndian.PutUint16(oldPortBytes[:], oldPort)
+		binary.BigEndian.PutUint16(newPortBytes[:], newPort)
+
+		newChecksum := incrementalUpdate(oldChecksum, oldPortBytes[:], newPortBytes[:])
+		binary.BigEndian.PutUint16(packetData[checksumOffset:checksumOffset+2], newChecksum)
+	}
+
+	return nil
+}
+
+// rewriteUDPPort rewrites a UDP port (source or destination) and updates checksum.
+func (m *Manager) rewriteUDPPort(packetData []byte, d *decoder, newPort uint16, portOffset int) error {
+	ipHeaderLen := int(d.ip4.IHL) * 4
+	if ipHeaderLen < 20 || ipHeaderLen > len(packetData) {
+		return errInvalidIPHeaderLength
+	}
+
+	udpStart := ipHeaderLen
+	if len(packetData) < udpStart+8 {
+		return fmt.Errorf("packet too short for UDP header")
+	}
+
+	portStart := udpStart + portOffset
+	oldPort := binary.BigEndian.Uint16(packetData[portStart : portStart+2])
+	binary.BigEndian.PutUint16(packetData[portStart:portStart+2], newPort)
+
+	checksumOffset := udpStart + 6
+	if len(packetData) >= udpStart+8 {
+		oldChecksum := binary.BigEndian.Uint16(packetData[checksumOffset : checksumOffset+2])
+		if oldChecksum != 0 {
+			var oldPortBytes, newPortBytes [2]byte
+			binary.BigEndian.PutUint16(oldPortBytes[:], oldPort)
+			binary.BigEndian.PutUint16(newPortBytes[:], newPort)
+
+			newChecksum := incrementalUpdate(oldChecksum, oldPortBytes[:], newPortBytes[:])
+			binary.BigEndian.PutUint16(packetData[checksumOffset:checksumOffset+2], newChecksum)
+		}
+	}
+
+	return nil
+}

client/firewall/uspfilter/nat_bench_test.go

@@ -12,6 +12,7 @@ import (
 
 	log "github.com/sirupsen/logrus"
 
+	"github.com/netbirdio/netbird/client/iface"
 	"github.com/netbirdio/netbird/client/iface/device"
 )
 
@@ -65,7 +66,7 @@ func BenchmarkDNATTranslation(b *testing.B) {
 		b.Run(sc.name, func(b *testing.B) {
 			manager, err := Create(&IFaceMock{
 				SetFilterFunc: func(device.PacketFilter) error { return nil },
-			}, false, flowLogger)
+			}, false, flowLogger, iface.DefaultMTU)
 			require.NoError(b, err)
 			defer func() {
 				require.NoError(b, manager.Close(nil))
@@ -125,7 +126,7 @@ func BenchmarkDNATTranslation(b *testing.B) {
 func BenchmarkDNATConcurrency(b *testing.B) {
 	manager, err := Create(&IFaceMock{
 		SetFilterFunc: func(device.PacketFilter) error { return nil },
-	}, false, flowLogger)
+	}, false, flowLogger, iface.DefaultMTU)
 	require.NoError(b, err)
 	defer func() {
 		require.NoError(b, manager.Close(nil))
@@ -197,7 +198,7 @@ func BenchmarkDNATScaling(b *testing.B) {
 		b.Run(fmt.Sprintf("mappings_%d", count), func(b *testing.B) {
 			manager, err := Create(&IFaceMock{
 				SetFilterFunc: func(device.PacketFilter) error { return nil },
-			}, false, flowLogger)
+			}, false, flowLogger, iface.DefaultMTU)
 			require.NoError(b, err)
 			defer func() {
 				require.NoError(b, manager.Close(nil))
@@ -309,7 +310,7 @@ func BenchmarkChecksumUpdate(b *testing.B) {
 func BenchmarkDNATMemoryAllocations(b *testing.B) {
 	manager, err := Create(&IFaceMock{
 		SetFilterFunc: func(device.PacketFilter) error { return nil },
-	}, false, flowLogger)
+	}, false, flowLogger, iface.DefaultMTU)
 	require.NoError(b, err)
 	defer func() {
 		require.NoError(b, manager.Close(nil))
@@ -414,3 +415,127 @@ func BenchmarkChecksumOptimizations(b *testing.B) {
 		}
 	})
 }
+
+// BenchmarkPortDNAT measures the performance of port DNAT operations
+func BenchmarkPortDNAT(b *testing.B) {
+	scenarios := []struct {
+		name         string
+		proto        layers.IPProtocol
+		setupDNAT    bool
+		useMatchPort bool
+		description  string
+	}{
+		{
+			name:         "tcp_inbound_dnat_match",
+			proto:        layers.IPProtocolTCP,
+			setupDNAT:    true,
+			useMatchPort: true,
+			description:  "TCP inbound port DNAT translation (22 → 22022)",
+		},
+		{
+			name:         "tcp_inbound_dnat_nomatch",
+			proto:        layers.IPProtocolTCP,
+			setupDNAT:    true,
+			useMatchPort: false,
+			description:  "TCP inbound with DNAT configured but no port match",
+		},
+		{
+			name:         "tcp_inbound_no_dnat",
+			proto:        layers.IPProtocolTCP,
+			setupDNAT:    false,
+			useMatchPort: false,
+			description:  "TCP inbound without DNAT (baseline)",
+		},
+		{
+			name:         "udp_inbound_dnat_match",
+			proto:        layers.IPProtocolUDP,
+			setupDNAT:    true,
+			useMatchPort: true,
+			description:  "UDP inbound port DNAT translation (5353 → 22054)",
+		},
+		{
+			name:         "udp_inbound_dnat_nomatch",
+			proto:        layers.IPProtocolUDP,
+			setupDNAT:    true,
+			useMatchPort: false,
+			description:  "UDP inbound with DNAT configured but no port match",
+		},
+		{
+			name:         "udp_inbound_no_dnat",
+			proto:        layers.IPProtocolUDP,
+			setupDNAT:    false,
+			useMatchPort: false,
+			description:  "UDP inbound without DNAT (baseline)",
+		},
+	}
+
+	for _, sc := range scenarios {
+		b.Run(sc.name, func(b *testing.B) {
+			manager, err := Create(&IFaceMock{
+				SetFilterFunc: func(device.PacketFilter) error { return nil },
+			}, false, flowLogger, iface.DefaultMTU)
+			require.NoError(b, err)
+			defer func() {
+				require.NoError(b, manager.Close(nil))
+			}()
+
+			// Set logger to error level to reduce noise during benchmarking
+			manager.SetLogLevel(log.ErrorLevel)
+			defer func() {
+				// Restore to info level after benchmark
+				manager.SetLogLevel(log.InfoLevel)
+			}()
+
+			localAddr := netip.MustParseAddr("100.0.2.175")
+			clientIP := netip.MustParseAddr("100.0.169.249")
+
+			var origPort, targetPort, testPort uint16
+			if sc.proto == layers.IPProtocolTCP {
+				origPort, targetPort = 22, 22022
+			} else {
+				origPort, targetPort = 5353, 22054
+			}
+
+			if sc.useMatchPort {
+				testPort = origPort
+			} else {
+				testPort = 443 // Different port
+			}
+
+			// Setup port DNAT mapping if needed
+			if sc.setupDNAT {
+				err := manager.AddInboundDNAT(localAddr, protocolToFirewall(sc.proto), origPort, targetPort)
+				require.NoError(b, err)
+			}
+
+			// Pre-establish inbound connection for outbound reverse test
+			if sc.setupDNAT && sc.useMatchPort {
+				inboundPacket := generateDNATTestPacket(b, clientIP, localAddr, sc.proto, 54321, origPort)
+				manager.filterInbound(inboundPacket, 0)
+			}
+
+			b.ResetTimer()
+			b.ReportAllocs()
+
+			// Benchmark inbound DNAT translation
+			b.Run("inbound", func(b *testing.B) {
+				for i := 0; i < b.N; i++ {
+					// Create fresh packet each time
+					packet := generateDNATTestPacket(b, clientIP, localAddr, sc.proto, 54321, testPort)
+					manager.filterInbound(packet, 0)
+				}
+			})
+
+			// Benchmark outbound reverse DNAT translation (only if DNAT is set up and port matches)
+			if sc.setupDNAT && sc.useMatchPort {
+				b.Run("outbound_reverse", func(b *testing.B) {
+					for i := 0; i < b.N; i++ {
+						// Create fresh return packet (from target port)
+						packet := generateDNATTestPacket(b, localAddr, clientIP, sc.proto, targetPort, 54321)
+						manager.filterOutbound(packet, 0)
+					}
+				})
+			}
+		})
+	}
+}

client/firewall/uspfilter/nat_test.go

@@ -8,6 +8,8 @@ import (
 	"github.com/google/gopacket/layers"
 	"github.com/stretchr/testify/require"
 
+	firewall "github.com/netbirdio/netbird/client/firewall/manager"
+	"github.com/netbirdio/netbird/client/iface"
 	"github.com/netbirdio/netbird/client/iface/device"
 )
 
@@ -15,7 +17,7 @@ import (
 func TestDNATTranslationCorrectness(t *testing.T) {
 	manager, err := Create(&IFaceMock{
 		SetFilterFunc: func(device.PacketFilter) error { return nil },
-	}, false, flowLogger)
+	}, false, flowLogger, iface.DefaultMTU)
 	require.NoError(t, err)
 	defer func() {
 		require.NoError(t, manager.Close(nil))
@@ -99,7 +101,7 @@ func parsePacket(t testing.TB, packetData []byte) *decoder {
 func TestDNATMappingManagement(t *testing.T) {
 	manager, err := Create(&IFaceMock{
 		SetFilterFunc: func(device.PacketFilter) error { return nil },
-	}, false, flowLogger)
+	}, false, flowLogger, iface.DefaultMTU)
 	require.NoError(t, err)
 	defer func() {
 		require.NoError(t, manager.Close(nil))
@@ -143,3 +145,111 @@ func TestDNATMappingManagement(t *testing.T) {
 	err = manager.RemoveInternalDNATMapping(originalIP)
 	require.Error(t, err, "Should error when removing non-existent mapping")
 }
+
+func TestInboundPortDNAT(t *testing.T) {
+	manager, err := Create(&IFaceMock{
+		SetFilterFunc: func(device.PacketFilter) error { return nil },
+	}, false, flowLogger, iface.DefaultMTU)
+	require.NoError(t, err)
+	defer func() {
+		require.NoError(t, manager.Close(nil))
+	}()
+
+	localAddr := netip.MustParseAddr("100.0.2.175")
+	clientIP := netip.MustParseAddr("100.0.169.249")
+
+	testCases := []struct {
+		name       string
+		protocol   layers.IPProtocol
+		sourcePort uint16
+		targetPort uint16
+	}{
+		{"TCP SSH", layers.IPProtocolTCP, 22, 22022},
+		{"UDP DNS", layers.IPProtocolUDP, 5353, 22054},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			err := manager.AddInboundDNAT(localAddr, protocolToFirewall(tc.protocol), tc.sourcePort, tc.targetPort)
+			require.NoError(t, err)
+
+			inboundPacket := generateDNATTestPacket(t, clientIP, localAddr, tc.protocol, 54321, tc.sourcePort)
+			d := parsePacket(t, inboundPacket)
+
+			translated := manager.translateInboundPortDNAT(inboundPacket, d, clientIP, localAddr)
+			require.True(t, translated, "Inbound packet should be translated")
+
+			d = parsePacket(t, inboundPacket)
+			var dstPort uint16
+			switch tc.protocol {
+			case layers.IPProtocolTCP:
+				dstPort = uint16(d.tcp.DstPort)
+			case layers.IPProtocolUDP:
+				dstPort = uint16(d.udp.DstPort)
+			}
+
+			require.Equal(t, tc.targetPort, dstPort, "Destination port should be rewritten to target port")
+
+			err = manager.RemoveInboundDNAT(localAddr, protocolToFirewall(tc.protocol), tc.sourcePort, tc.targetPort)
+			require.NoError(t, err)
+		})
+	}
+}
+
+func TestInboundPortDNATNegative(t *testing.T) {
+	manager, err := Create(&IFaceMock{
+		SetFilterFunc: func(device.PacketFilter) error { return nil },
+	}, false, flowLogger, iface.DefaultMTU)
+	require.NoError(t, err)
+	defer func() {
+		require.NoError(t, manager.Close(nil))
+	}()
+
+	localAddr := netip.MustParseAddr("100.0.2.175")
+	clientIP := netip.MustParseAddr("100.0.169.249")
+
+	err = manager.AddInboundDNAT(localAddr, firewall.ProtocolTCP, 22, 22022)
+	require.NoError(t, err)
+
+	testCases := []struct {
+		name     string
+		protocol layers.IPProtocol
+		srcIP    netip.Addr
+		dstIP    netip.Addr
+		srcPort  uint16
+		dstPort  uint16
+	}{
+		{"Wrong port", layers.IPProtocolTCP, clientIP, localAddr, 54321, 80},
+		{"Wrong IP", layers.IPProtocolTCP, clientIP, netip.MustParseAddr("100.64.0.99"), 54321, 22},
+		{"Wrong protocol", layers.IPProtocolUDP, clientIP, localAddr, 54321, 22},
+		{"ICMP", layers.IPProtocolICMPv4, clientIP, localAddr, 0, 0},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			packet := generateDNATTestPacket(t, tc.srcIP, tc.dstIP, tc.protocol, tc.srcPort, tc.dstPort)
+			d := parsePacket(t, packet)
+
+			translated := manager.translateInboundPortDNAT(packet, d, tc.srcIP, tc.dstIP)
+			require.False(t, translated, "Packet should NOT be translated for %s", tc.name)
+
+			d = parsePacket(t, packet)
+			if tc.protocol == layers.IPProtocolTCP {
+				require.Equal(t, tc.dstPort, uint16(d.tcp.DstPort), "Port should remain unchanged")
+			} else if tc.protocol == layers.IPProtocolUDP {
+				require.Equal(t, tc.dstPort, uint16(d.udp.DstPort), "Port should remain unchanged")
+			}
+		})
+	}
+}
+
+func protocolToFirewall(proto layers.IPProtocol) firewall.Protocol {
+	switch proto {
+	case layers.IPProtocolTCP:
+		return firewall.ProtocolTCP
+	case layers.IPProtocolUDP:
+		return firewall.ProtocolUDP
+	default:
+		return firewall.ProtocolALL
+	}
+}

client/firewall/uspfilter/tracer.go

@@ -16,25 +16,33 @@ type PacketStage int
 
 const (
 	StageReceived PacketStage = iota
+	StageInboundPortDNAT
+	StageInbound1to1NAT
 	StageConntrack
 	StagePeerACL
 	StageRouting
 	StageRouteACL
 	StageForwarding
 	StageCompleted
+	StageOutbound1to1NAT
+	StageOutboundPortReverse
 )
 
 const msgProcessingCompleted = "Processing completed"
 
 func (s PacketStage) String() string {
 	return map[PacketStage]string{
-		StageReceived:   "Received",
-		StageConntrack:  "Connection Tracking",
-		StagePeerACL:    "Peer ACL",
-		StageRouting:    "Routing",
-		StageRouteACL:   "Route ACL",
-		StageForwarding: "Forwarding",
-		StageCompleted:  "Completed",
+		StageReceived:            "Received",
+		StageInboundPortDNAT:     "Inbound Port DNAT",
+		StageInbound1to1NAT:      "Inbound 1:1 NAT",
+		StageConntrack:           "Connection Tracking",
+		StagePeerACL:             "Peer ACL",
+		StageRouting:             "Routing",
+		StageRouteACL:            "Route ACL",
+		StageForwarding:          "Forwarding",
+		StageCompleted:           "Completed",
+		StageOutbound1to1NAT:     "Outbound 1:1 NAT",
+		StageOutboundPortReverse: "Outbound DNAT Reverse",
 	}[s]
 }
 
@@ -261,6 +269,10 @@ func (m *Manager) TracePacket(packetData []byte, direction fw.RuleDirection) *Pa
 }
 
 func (m *Manager) traceInbound(packetData []byte, trace *PacketTrace, d *decoder, srcIP netip.Addr, dstIP netip.Addr) *PacketTrace {
+	if m.handleInboundDNAT(trace, packetData, d, &srcIP, &dstIP) {
+		return trace
+	}
+
 	if m.stateful && m.handleConntrackState(trace, d, srcIP, dstIP) {
 		return trace
 	}
@@ -400,7 +412,16 @@ func (m *Manager) addForwardingResult(trace *PacketTrace, action, remoteAddr str
 }
 
 func (m *Manager) traceOutbound(packetData []byte, trace *PacketTrace) *PacketTrace {
-	// will create or update the connection state
+	d := m.decoders.Get().(*decoder)
+	defer m.decoders.Put(d)
+
+	if err := d.parser.DecodeLayers(packetData, &d.decoded); err != nil {
+		trace.AddResult(StageCompleted, "Packet dropped - decode error", false)
+		return trace
+	}
+
+	m.handleOutboundDNAT(trace, packetData, d)
+
 	dropped := m.filterOutbound(packetData, 0)
 	if dropped {
 		trace.AddResult(StageCompleted, "Packet dropped by outgoing hook", false)
@@ -409,3 +430,199 @@ func (m *Manager) traceOutbound(packetData []byte, trace *PacketTrace) *PacketTr
 	}
 	return trace
 }
+
+func (m *Manager) handleInboundDNAT(trace *PacketTrace, packetData []byte, d *decoder, srcIP, dstIP *netip.Addr) bool {
+	portDNATApplied := m.traceInboundPortDNAT(trace, packetData, d)
+	if portDNATApplied {
+		if err := d.parser.DecodeLayers(packetData, &d.decoded); err != nil {
+			trace.AddResult(StageInboundPortDNAT, "Failed to re-decode after port DNAT", false)
+			return true
+		}
+		*srcIP, *dstIP = m.extractIPs(d)
+		trace.DestinationPort = m.getDestPort(d)
+	}
+
+	nat1to1Applied := m.traceInbound1to1NAT(trace, packetData, d)
+	if nat1to1Applied {
+		if err := d.parser.DecodeLayers(packetData, &d.decoded); err != nil {
+			trace.AddResult(StageInbound1to1NAT, "Failed to re-decode after 1:1 NAT", false)
+			return true
+		}
+		*srcIP, *dstIP = m.extractIPs(d)
+	}
+
+	return false
+}
+
+func (m *Manager) traceInboundPortDNAT(trace *PacketTrace, packetData []byte, d *decoder) bool {
+	if !m.portDNATEnabled.Load() {
+		trace.AddResult(StageInboundPortDNAT, "Port DNAT not enabled", true)
+		return false
+	}
+
+	if len(packetData) < 20 || d.decoded[0] != layers.LayerTypeIPv4 {
+		trace.AddResult(StageInboundPortDNAT, "Not IPv4, skipping port DNAT", true)
+		return false
+	}
+
+	if len(d.decoded) < 2 {
+		trace.AddResult(StageInboundPortDNAT, "No transport layer, skipping port DNAT", true)
+		return false
+	}
+
+	protocol := d.decoded[1]
+	if protocol != layers.LayerTypeTCP && protocol != layers.LayerTypeUDP {
+		trace.AddResult(StageInboundPortDNAT, "Not TCP/UDP, skipping port DNAT", true)
+		return false
+	}
+
+	srcIP := netip.AddrFrom4([4]byte{packetData[12], packetData[13], packetData[14], packetData[15]})
+	dstIP := netip.AddrFrom4([4]byte{packetData[16], packetData[17], packetData[18], packetData[19]})
+	var originalPort uint16
+	if protocol == layers.LayerTypeTCP {
+		originalPort = uint16(d.tcp.DstPort)
+	} else {
+		originalPort = uint16(d.udp.DstPort)
+	}
+
+	translated := m.translateInboundPortDNAT(packetData, d, srcIP, dstIP)
+	if translated {
+		ipHeaderLen := int((packetData[0] & 0x0F) * 4)
+		translatedPort := uint16(packetData[ipHeaderLen+2])<<8 | uint16(packetData[ipHeaderLen+3])
+
+		protoStr := "TCP"
+		if protocol == layers.LayerTypeUDP {
+			protoStr = "UDP"
+		}
+		msg := fmt.Sprintf("%s port DNAT applied: %s:%d -> %s:%d", protoStr, dstIP, originalPort, dstIP, translatedPort)
+		trace.AddResult(StageInboundPortDNAT, msg, true)
+		return true
+	}
+
+	trace.AddResult(StageInboundPortDNAT, "No matching port DNAT rule", true)
+	return false
+}
+
+func (m *Manager) traceInbound1to1NAT(trace *PacketTrace, packetData []byte, d *decoder) bool {
+	if !m.dnatEnabled.Load() {
+		trace.AddResult(StageInbound1to1NAT, "1:1 NAT not enabled", true)
+		return false
+	}
+
+	srcIP := netip.AddrFrom4([4]byte{packetData[12], packetData[13], packetData[14], packetData[15]})
+
+	translated := m.translateInboundReverse(packetData, d)
+	if translated {
+		m.dnatMutex.RLock()
+		translatedIP, exists := m.dnatBiMap.getOriginal(srcIP)
+		m.dnatMutex.RUnlock()
+
+		if exists {
+			msg := fmt.Sprintf("1:1 NAT reverse applied: %s -> %s", srcIP, translatedIP)
+			trace.AddResult(StageInbound1to1NAT, msg, true)
+			return true
+		}
+	}
+
+	trace.AddResult(StageInbound1to1NAT, "No matching 1:1 NAT rule", true)
+	return false
+}
+
+func (m *Manager) handleOutboundDNAT(trace *PacketTrace, packetData []byte, d *decoder) {
+	m.traceOutbound1to1NAT(trace, packetData, d)
+	m.traceOutboundPortReverse(trace, packetData, d)
+}
+
+func (m *Manager) traceOutbound1to1NAT(trace *PacketTrace, packetData []byte, d *decoder) bool {
+	if !m.dnatEnabled.Load() {
+		trace.AddResult(StageOutbound1to1NAT, "1:1 NAT not enabled", true)
+		return false
+	}
+
+	dstIP := netip.AddrFrom4([4]byte{packetData[16], packetData[17], packetData[18], packetData[19]})
+
+	translated := m.translateOutboundDNAT(packetData, d)
+	if translated {
+		m.dnatMutex.RLock()
+		translatedIP, exists := m.dnatMappings[dstIP]
+		m.dnatMutex.RUnlock()
+
+		if exists {
+			msg := fmt.Sprintf("1:1 NAT applied: %s -> %s", dstIP, translatedIP)
+			trace.AddResult(StageOutbound1to1NAT, msg, true)
+			return true
+		}
+	}
+
+	trace.AddResult(StageOutbound1to1NAT, "No matching 1:1 NAT rule", true)
+	return false
+}
+
+func (m *Manager) traceOutboundPortReverse(trace *PacketTrace, packetData []byte, d *decoder) bool {
+	if !m.portDNATEnabled.Load() {
+		trace.AddResult(StageOutboundPortReverse, "Port DNAT not enabled", true)
+		return false
+	}
+
+	if len(packetData) < 20 || d.decoded[0] != layers.LayerTypeIPv4 {
+		trace.AddResult(StageOutboundPortReverse, "Not IPv4, skipping port reverse", true)
+		return false
+	}
+
+	if len(d.decoded) < 2 {
+		trace.AddResult(StageOutboundPortReverse, "No transport layer, skipping port reverse", true)
+		return false
+	}
+
+	srcIP := netip.AddrFrom4([4]byte{packetData[12], packetData[13], packetData[14], packetData[15]})
+	dstIP := netip.AddrFrom4([4]byte{packetData[16], packetData[17], packetData[18], packetData[19]})
+
+	var origPort uint16
+	transport := d.decoded[1]
+	switch transport {
+	case layers.LayerTypeTCP:
+		srcPort := uint16(d.tcp.SrcPort)
+		dstPort := uint16(d.tcp.DstPort)
+		conn, exists := m.tcpTracker.GetConnection(dstIP, dstPort, srcIP, srcPort)
+		if exists {
+			origPort = uint16(conn.DNATOrigPort.Load())
+		}
+		if origPort != 0 {
+			msg := fmt.Sprintf("TCP DNAT reverse (tracked connection): %s:%d -> %s:%d", srcIP, srcPort, srcIP, origPort)
+			trace.AddResult(StageOutboundPortReverse, msg, true)
+			return true
+		}
+	case layers.LayerTypeUDP:
+		srcPort := uint16(d.udp.SrcPort)
+		dstPort := uint16(d.udp.DstPort)
+		conn, exists := m.udpTracker.GetConnection(dstIP, dstPort, srcIP, srcPort)
+		if exists {
+			origPort = uint16(conn.DNATOrigPort.Load())
+		}
+		if origPort != 0 {
+			msg := fmt.Sprintf("UDP DNAT reverse (tracked connection): %s:%d -> %s:%d", srcIP, srcPort, srcIP, origPort)
+			trace.AddResult(StageOutboundPortReverse, msg, true)
+			return true
+		}
+	default:
+		trace.AddResult(StageOutboundPortReverse, "Not TCP/UDP, skipping port reverse", true)
+		return false
+	}
+
+	trace.AddResult(StageOutboundPortReverse, "No tracked connection for DNAT reverse", true)
+	return false
+}
+
+func (m *Manager) getDestPort(d *decoder) uint16 {
+	if len(d.decoded) < 2 {
+		return 0
+	}
+	switch d.decoded[1] {
+	case layers.LayerTypeTCP:
+		return uint16(d.tcp.DstPort)
+	case layers.LayerTypeUDP:
+		return uint16(d.udp.DstPort)
+	default:
+		return 0
+	}
+}

client/firewall/uspfilter/tracer_test.go

@@ -10,6 +10,7 @@ import (
 	fw "github.com/netbirdio/netbird/client/firewall/manager"
 	"github.com/netbirdio/netbird/client/firewall/uspfilter/conntrack"
 	"github.com/netbirdio/netbird/client/firewall/uspfilter/forwarder"
+	"github.com/netbirdio/netbird/client/iface"
 	"github.com/netbirdio/netbird/client/iface/device"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 )
@@ -44,7 +45,7 @@ func TestTracePacket(t *testing.T) {
 			},
 		}
 
-		m, err := Create(ifaceMock, false, flowLogger)
+		m, err := Create(ifaceMock, false, flowLogger, iface.DefaultMTU)
 		require.NoError(t, err)
 
 		if !statefulMode {
@@ -104,6 +105,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageConntrack,
 				StageRouting,
 				StagePeerACL,
@@ -126,6 +129,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageConntrack,
 				StageRouting,
 				StagePeerACL,
@@ -153,6 +158,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageConntrack,
 				StageRouting,
 				StagePeerACL,
@@ -179,6 +186,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageConntrack,
 				StageRouting,
 				StagePeerACL,
@@ -204,6 +213,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageConntrack,
 				StageRouting,
 				StageRouteACL,
@@ -228,6 +239,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageConntrack,
 				StageRouting,
 				StageRouteACL,
@@ -246,6 +259,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageConntrack,
 				StageRouting,
 				StageRouteACL,
@@ -264,6 +279,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageConntrack,
 				StageRouting,
 				StageCompleted,
@@ -287,6 +304,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageConntrack,
 				StageCompleted,
 			},
@@ -301,6 +320,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageOutbound1to1NAT,
+				StageOutboundPortReverse,
 				StageCompleted,
 			},
 			expectedAllow: true,
@@ -319,6 +340,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageConntrack,
 				StageRouting,
 				StagePeerACL,
@@ -340,6 +363,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageConntrack,
 				StageRouting,
 				StagePeerACL,
@@ -362,6 +387,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageConntrack,
 				StageRouting,
 				StagePeerACL,
@@ -382,6 +409,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageConntrack,
 				StageRouting,
 				StagePeerACL,
@@ -406,6 +435,8 @@ func TestTracePacket(t *testing.T) {
 			},
 			expectedStages: []PacketStage{
 				StageReceived,
+				StageInboundPortDNAT,
+				StageInbound1to1NAT,
 				StageRouting,
 				StagePeerACL,
 				StageCompleted,

client/grpc/dialer.go

@@ -0,0 +1,93 @@
+package grpc
+
+import (
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"errors"
+	"fmt"
+	"runtime"
+	"time"
+
+	"github.com/cenkalti/backoff/v4"
+	log "github.com/sirupsen/logrus"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/connectivity"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/credentials/insecure"
+	"google.golang.org/grpc/keepalive"
+
+	"github.com/netbirdio/netbird/util/embeddedroots"
+)
+
+// ErrConnectionShutdown indicates that the connection entered shutdown state before becoming ready
+var ErrConnectionShutdown = errors.New("connection shutdown before ready")
+
+// Backoff returns a backoff configuration for gRPC calls
+func Backoff(ctx context.Context) backoff.BackOff {
+	b := backoff.NewExponentialBackOff()
+	b.MaxElapsedTime = 10 * time.Second
+	b.Clock = backoff.SystemClock
+	return backoff.WithContext(b, ctx)
+}
+
+// waitForConnectionReady blocks until the connection becomes ready or fails.
+// Returns an error if the connection times out, is cancelled, or enters shutdown state.
+func waitForConnectionReady(ctx context.Context, conn *grpc.ClientConn) error {
+	conn.Connect()
+
+	state := conn.GetState()
+	for state != connectivity.Ready && state != connectivity.Shutdown {
+		if !conn.WaitForStateChange(ctx, state) {
+			return fmt.Errorf("wait state change from %s: %w", state, ctx.Err())
+		}
+		state = conn.GetState()
+	}
+
+	if state == connectivity.Shutdown {
+		return ErrConnectionShutdown
+	}
+
+	return nil
+}
+
+// CreateConnection creates a gRPC client connection with the appropriate transport options.
+// The component parameter specifies the WebSocket proxy component path (e.g., "/management", "/signal").
+func CreateConnection(ctx context.Context, addr string, tlsEnabled bool, component string) (*grpc.ClientConn, error) {
+	transportOption := grpc.WithTransportCredentials(insecure.NewCredentials())
+	// for js, the outer websocket layer takes care of tls
+	if tlsEnabled && runtime.GOOS != "js" {
+		certPool, err := x509.SystemCertPool()
+		if err != nil || certPool == nil {
+			log.Debugf("System cert pool not available; falling back to embedded cert, error: %v", err)
+			certPool = embeddedroots.Get()
+		}
+
+		transportOption = grpc.WithTransportCredentials(credentials.NewTLS(&tls.Config{
+			RootCAs: certPool,
+		}))
+	}
+
+	conn, err := grpc.NewClient(
+		addr,
+		transportOption,
+		WithCustomDialer(tlsEnabled, component),
+		grpc.WithKeepaliveParams(keepalive.ClientParameters{
+			Time:    30 * time.Second,
+			Timeout: 10 * time.Second,
+		}),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("new client: %w", err)
+	}
+
+	ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
+	defer cancel()
+
+	if err := waitForConnectionReady(ctx, conn); err != nil {
+		_ = conn.Close()
+		return nil, err
+	}
+
+	return conn, nil
+}

client/grpc/dialer_generic.go

@@ -0,0 +1,43 @@
+//go:build !js
+
+package grpc
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"os/user"
+	"runtime"
+
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
+	log "github.com/sirupsen/logrus"
+	"google.golang.org/grpc"
+
+	nbnet "github.com/netbirdio/netbird/client/net"
+)
+
+func WithCustomDialer(_ bool, _ string) grpc.DialOption {
+	return grpc.WithContextDialer(func(ctx context.Context, addr string) (net.Conn, error) {
+		if runtime.GOOS == "linux" {
+			currentUser, err := user.Current()
+			if err != nil {
+				return nil, status.Errorf(codes.FailedPrecondition, "failed to get current user: %v", err)
+			}
+
+			// the custom dialer requires root permissions which are not required for use cases run as non-root
+			if currentUser.Uid != "0" {
+				log.Debug("Not running as root, using standard dialer")
+				dialer := &net.Dialer{}
+				return dialer.DialContext(ctx, "tcp", addr)
+			}
+		}
+
+		conn, err := nbnet.NewDialer().DialContext(ctx, "tcp", addr)
+		if err != nil {
+			return nil, fmt.Errorf("nbnet.NewDialer().DialContext: %w", err)
+		}
+		return conn, nil
+	})
+}

client/grpc/dialer_js.go

@@ -0,0 +1,13 @@
+package grpc
+
+import (
+	"google.golang.org/grpc"
+
+	"github.com/netbirdio/netbird/util/wsproxy/client"
+)
+
+// WithCustomDialer returns a gRPC dial option that uses WebSocket transport for WASM/JS environments.
+// The component parameter specifies the WebSocket proxy component path (e.g., "/management", "/signal").
+func WithCustomDialer(tlsEnabled bool, component string) grpc.DialOption {
+	return client.WithWebSocketDialer(tlsEnabled, component)
+}

client/iface/bind/control.go

@@ -3,7 +3,7 @@ package bind
 import (
 	wireguard "golang.zx2c4.com/wireguard/conn"
 
-	nbnet "github.com/netbirdio/netbird/util/net"
+	nbnet "github.com/netbirdio/netbird/client/net"
 )
 
 // TODO: This is most likely obsolete since the control fns should be called by the wrapped udpconn (ice_bind.go)

client/iface/bind/endpoint.go

@@ -1,5 +1,17 @@
 package bind
 
-import wgConn "golang.zx2c4.com/wireguard/conn"
+import (
+	"net"
+
+	wgConn "golang.zx2c4.com/wireguard/conn"
+)
 
 type Endpoint = wgConn.StdNetEndpoint
+
+func EndpointToUDPAddr(e Endpoint) *net.UDPAddr {
+	return &net.UDPAddr{
+		IP:   e.Addr().AsSlice(),
+		Port: int(e.Port()),
+		Zone: e.Addr().Zone(),
+	}
+}

client/iface/bind/error.go

@@ -0,0 +1,7 @@
+package bind
+
+import "fmt"
+
+var (
+	ErrUDPMUXNotSupported = fmt.Errorf("UDPMUX is not supported in WASM")
+)

client/iface/bind/ice_bind.go

@@ -1,6 +1,9 @@
+//go:build !js
+
 package bind
 
 import (
+	"context"
 	"encoding/binary"
 	"fmt"
 	"net"
@@ -8,22 +11,18 @@ import (
 	"runtime"
 	"sync"
 
-	"github.com/pion/stun/v2"
+	"github.com/pion/stun/v3"
 	"github.com/pion/transport/v3"
 	log "github.com/sirupsen/logrus"
 	"golang.org/x/net/ipv4"
 	"golang.org/x/net/ipv6"
 	wgConn "golang.zx2c4.com/wireguard/conn"
 
+	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
-	nbnet "github.com/netbirdio/netbird/util/net"
+	nbnet "github.com/netbirdio/netbird/client/net"
 )
 
-type RecvMessage struct {
-	Endpoint *Endpoint
-	Buffer   []byte
-}
-
 type receiverCreator struct {
 	iceBind *ICEBind
 }
@@ -41,35 +40,38 @@ func (rc receiverCreator) CreateIPv4ReceiverFn(pc *ipv4.PacketConn, conn *net.UD
 // use the port because in the Send function the wgConn.Endpoint the port info is not exported.
 type ICEBind struct {
 	*wgConn.StdNetBind
-	RecvChan chan RecvMessage
 
 	transportNet transport.Net
-	filterFn     FilterFn
-	endpoints    map[netip.Addr]net.Conn
-	endpointsMu  sync.Mutex
+	filterFn     udpmux.FilterFn
+	address      wgaddr.Address
+	mtu          uint16
+
+	endpoints   map[netip.Addr]net.Conn
+	endpointsMu sync.Mutex
+	recvChan    chan recvMessage
 	// every time when Close() is called (i.e. BindUpdate()) we need to close exit from the receiveRelayed and create a
 	// new closed channel. With the closedChanMu we can safely close the channel and create a new one
-	closedChan   chan struct{}
-	closedChanMu sync.RWMutex // protect the closeChan recreation from reading from it.
-	closed       bool
-
-	muUDPMux         sync.Mutex
-	udpMux           *UniversalUDPMuxDefault
-	address          wgaddr.Address
+	closedChan       chan struct{}
+	closedChanMu     sync.RWMutex // protect the closeChan recreation from reading from it.
+	closed           bool
 	activityRecorder *ActivityRecorder
+
+	muUDPMux sync.Mutex
+	udpMux   *udpmux.UniversalUDPMuxDefault
 }
 
-func NewICEBind(transportNet transport.Net, filterFn FilterFn, address wgaddr.Address) *ICEBind {
+func NewICEBind(transportNet transport.Net, filterFn udpmux.FilterFn, address wgaddr.Address, mtu uint16) *ICEBind {
 	b, _ := wgConn.NewStdNetBind().(*wgConn.StdNetBind)
 	ib := &ICEBind{
 		StdNetBind:       b,
-		RecvChan:         make(chan RecvMessage, 1),
 		transportNet:     transportNet,
 		filterFn:         filterFn,
+		address:          address,
+		mtu:              mtu,
 		endpoints:        make(map[netip.Addr]net.Conn),
+		recvChan:         make(chan recvMessage, 1),
 		closedChan:       make(chan struct{}),
 		closed:           true,
-		address:          address,
 		activityRecorder: NewActivityRecorder(),
 	}
 
@@ -109,7 +111,7 @@ func (s *ICEBind) ActivityRecorder() *ActivityRecorder {
 }
 
 // GetICEMux returns the ICE UDPMux that was created and used by ICEBind
-func (s *ICEBind) GetICEMux() (*UniversalUDPMuxDefault, error) {
+func (s *ICEBind) GetICEMux() (*udpmux.UniversalUDPMuxDefault, error) {
 	s.muUDPMux.Lock()
 	defer s.muUDPMux.Unlock()
 	if s.udpMux == nil {
@@ -132,6 +134,16 @@ func (b *ICEBind) RemoveEndpoint(fakeIP netip.Addr) {
 	delete(b.endpoints, fakeIP)
 }
 
+func (b *ICEBind) ReceiveFromEndpoint(ctx context.Context, ep *Endpoint, buf []byte) {
+	select {
+	case <-b.closedChan:
+		return
+	case <-ctx.Done():
+		return
+	case b.recvChan <- recvMessage{ep, buf}:
+	}
+}
+
 func (b *ICEBind) Send(bufs [][]byte, ep wgConn.Endpoint) error {
 	b.endpointsMu.Lock()
 	conn, ok := b.endpoints[ep.DstIP()]
@@ -152,12 +164,13 @@ func (s *ICEBind) createIPv4ReceiverFn(pc *ipv4.PacketConn, conn *net.UDPConn, r
 	s.muUDPMux.Lock()
 	defer s.muUDPMux.Unlock()
 
-	s.udpMux = NewUniversalUDPMuxDefault(
-		UniversalUDPMuxParams{
+	s.udpMux = udpmux.NewUniversalUDPMuxDefault(
+		udpmux.UniversalUDPMuxParams{
 			UDPConn:   nbnet.WrapPacketConn(conn),
 			Net:       s.transportNet,
 			FilterFn:  s.filterFn,
 			WGAddress: s.address,
+			MTU:       s.mtu,
 		},
 	)
 	return func(bufs [][]byte, sizes []int, eps []wgConn.Endpoint) (n int, err error) {
@@ -263,7 +276,7 @@ func (c *ICEBind) receiveRelayed(buffs [][]byte, sizes []int, eps []wgConn.Endpo
 	select {
 	case <-c.closedChan:
 		return 0, net.ErrClosed
-	case msg, ok := <-c.RecvChan:
+	case msg, ok := <-c.recvChan:
 		if !ok {
 			return 0, net.ErrClosed
 		}

client/iface/bind/recv_msg.go

@@ -0,0 +1,6 @@
+package bind
+
+type recvMessage struct {
+	Endpoint *Endpoint
+	Buffer   []byte
+}

client/iface/bind/relay_bind.go

@@ -0,0 +1,125 @@
+package bind
+
+import (
+	"context"
+	"net"
+	"net/netip"
+	"sync"
+
+	log "github.com/sirupsen/logrus"
+	"golang.zx2c4.com/wireguard/conn"
+
+	"github.com/netbirdio/netbird/client/iface/udpmux"
+)
+
+// RelayBindJS is a conn.Bind implementation for WebAssembly environments.
+// Do not limit to build only js, because we want to be able to run tests
+type RelayBindJS struct {
+	*conn.StdNetBind
+
+	recvChan         chan recvMessage
+	endpoints        map[netip.Addr]net.Conn
+	endpointsMu      sync.Mutex
+	activityRecorder *ActivityRecorder
+	ctx              context.Context
+	cancel           context.CancelFunc
+}
+
+func NewRelayBindJS() *RelayBindJS {
+	return &RelayBindJS{
+		recvChan:         make(chan recvMessage, 100),
+		endpoints:        make(map[netip.Addr]net.Conn),
+		activityRecorder: NewActivityRecorder(),
+	}
+}
+
+// Open creates a receive function for handling relay packets in WASM.
+func (s *RelayBindJS) Open(uport uint16) ([]conn.ReceiveFunc, uint16, error) {
+	log.Debugf("Open: creating receive function for port %d", uport)
+
+	s.ctx, s.cancel = context.WithCancel(context.Background())
+
+	receiveFn := func(bufs [][]byte, sizes []int, eps []conn.Endpoint) (int, error) {
+		select {
+		case <-s.ctx.Done():
+			return 0, net.ErrClosed
+		case msg, ok := <-s.recvChan:
+			if !ok {
+				return 0, net.ErrClosed
+			}
+			copy(bufs[0], msg.Buffer)
+			sizes[0] = len(msg.Buffer)
+			eps[0] = conn.Endpoint(msg.Endpoint)
+			return 1, nil
+		}
+	}
+
+	log.Debugf("Open: receive function created, returning port %d", uport)
+	return []conn.ReceiveFunc{receiveFn}, uport, nil
+}
+
+func (s *RelayBindJS) Close() error {
+	if s.cancel == nil {
+		return nil
+	}
+	log.Debugf("close RelayBindJS")
+	s.cancel()
+	return nil
+}
+
+func (s *RelayBindJS) ReceiveFromEndpoint(ctx context.Context, ep *Endpoint, buf []byte) {
+	select {
+	case <-s.ctx.Done():
+		return
+	case <-ctx.Done():
+		return
+	case s.recvChan <- recvMessage{ep, buf}:
+	}
+}
+
+// Send forwards packets through the relay connection for WASM.
+func (s *RelayBindJS) Send(bufs [][]byte, ep conn.Endpoint) error {
+	if ep == nil {
+		return nil
+	}
+
+	fakeIP := ep.DstIP()
+
+	s.endpointsMu.Lock()
+	relayConn, ok := s.endpoints[fakeIP]
+	s.endpointsMu.Unlock()
+
+	if !ok {
+		return nil
+	}
+
+	for _, buf := range bufs {
+		if _, err := relayConn.Write(buf); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (b *RelayBindJS) SetEndpoint(fakeIP netip.Addr, conn net.Conn) {
+	b.endpointsMu.Lock()
+	b.endpoints[fakeIP] = conn
+	b.endpointsMu.Unlock()
+}
+
+func (s *RelayBindJS) RemoveEndpoint(fakeIP netip.Addr) {
+	s.endpointsMu.Lock()
+	defer s.endpointsMu.Unlock()
+
+	delete(s.endpoints, fakeIP)
+}
+
+// GetICEMux returns the ICE UDPMux that was created and used by ICEBind
+func (s *RelayBindJS) GetICEMux() (*udpmux.UniversalUDPMuxDefault, error) {
+	return nil, ErrUDPMUXNotSupported
+}
+
+func (s *RelayBindJS) ActivityRecorder() *ActivityRecorder {
+	return s.activityRecorder
+}

client/iface/bind/udp_mux_ios.go

@@ -1,7 +0,0 @@
-//go:build ios
-
-package bind
-
-func (m *UDPMuxDefault) notifyAddressRemoval(addr string) {
-	// iOS doesn't support nbnet hooks, so this is a no-op
-}

client/iface/bufsize/bufsize.go

@@ -0,0 +1,9 @@
+package bufsize
+
+const (
+	// WGBufferOverhead represents the additional buffer space needed beyond MTU
+	// for WireGuard packet encapsulation (WG header + UDP + IP + safety margin)
+	// Original hardcoded buffers were 1500, default MTU is 1280, so overhead = 220
+	// TODO: Calculate this properly based on actual protocol overhead instead of using hardcoded difference
+	WGBufferOverhead = 220
+)

client/iface/configurer/kernel_unix.go

@@ -73,6 +73,44 @@ func (c *KernelConfigurer) UpdatePeer(peerKey string, allowedIps []netip.Prefix,
 	return nil
 }
 
+func (c *KernelConfigurer) RemoveEndpointAddress(peerKey string) error {
+	peerKeyParsed, err := wgtypes.ParseKey(peerKey)
+	if err != nil {
+		return err
+	}
+
+	// Get the existing peer to preserve its allowed IPs
+	existingPeer, err := c.getPeer(c.deviceName, peerKey)
+	if err != nil {
+		return fmt.Errorf("get peer: %w", err)
+	}
+
+	removePeerCfg := wgtypes.PeerConfig{
+		PublicKey: peerKeyParsed,
+		Remove:    true,
+	}
+
+	if err := c.configure(wgtypes.Config{Peers: []wgtypes.PeerConfig{removePeerCfg}}); err != nil {
+		return fmt.Errorf(`error removing peer %s from interface %s: %w`, peerKey, c.deviceName, err)
+	}
+
+	//Re-add the peer without the endpoint but same AllowedIPs
+	reAddPeerCfg := wgtypes.PeerConfig{
+		PublicKey:         peerKeyParsed,
+		AllowedIPs:        existingPeer.AllowedIPs,
+		ReplaceAllowedIPs: true,
+	}
+
+	if err := c.configure(wgtypes.Config{Peers: []wgtypes.PeerConfig{reAddPeerCfg}}); err != nil {
+		return fmt.Errorf(
+			`error re-adding peer %s to interface %s with allowed IPs %v: %w`,
+			peerKey, c.deviceName, existingPeer.AllowedIPs, err,
+		)
+	}
+
+	return nil
+}
+
 func (c *KernelConfigurer) RemovePeer(peerKey string) error {
 	peerKeyParsed, err := wgtypes.ParseKey(peerKey)
 	if err != nil {

client/iface/configurer/name.go

@@ -1,4 +1,4 @@
-//go:build linux || windows || freebsd
+//go:build linux || windows || freebsd || js || wasip1
 
 package configurer
 

client/iface/configurer/uapi.go

@@ -1,4 +1,4 @@
-//go:build !windows
+//go:build !windows && !js
 
 package configurer
 

client/iface/configurer/uapi_js.go

@@ -0,0 +1,23 @@
+package configurer
+
+import (
+	"net"
+)
+
+type noopListener struct{}
+
+func (n *noopListener) Accept() (net.Conn, error) {
+	return nil, net.ErrClosed
+}
+
+func (n *noopListener) Close() error {
+	return nil
+}
+
+func (n *noopListener) Addr() net.Addr {
+	return nil
+}
+
+func openUAPI(deviceName string) (net.Listener, error) {
+	return &noopListener{}, nil
+}

client/iface/configurer/usp.go

@@ -17,8 +17,8 @@ import (
 	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
 
 	"github.com/netbirdio/netbird/client/iface/bind"
+	nbnet "github.com/netbirdio/netbird/client/net"
 	"github.com/netbirdio/netbird/monotime"
-	nbnet "github.com/netbirdio/netbird/util/net"
 )
 
 const (
@@ -106,6 +106,67 @@ func (c *WGUSPConfigurer) UpdatePeer(peerKey string, allowedIps []netip.Prefix,
 	return nil
 }
 
+func (c *WGUSPConfigurer) RemoveEndpointAddress(peerKey string) error {
+	peerKeyParsed, err := wgtypes.ParseKey(peerKey)
+	if err != nil {
+		return fmt.Errorf("parse peer key: %w", err)
+	}
+
+	ipcStr, err := c.device.IpcGet()
+	if err != nil {
+		return fmt.Errorf("get IPC config: %w", err)
+	}
+
+	// Parse current status to get allowed IPs for the peer
+	stats, err := parseStatus(c.deviceName, ipcStr)
+	if err != nil {
+		return fmt.Errorf("parse IPC config: %w", err)
+	}
+
+	var allowedIPs []net.IPNet
+	found := false
+	for _, peer := range stats.Peers {
+		if peer.PublicKey == peerKey {
+			allowedIPs = peer.AllowedIPs
+			found = true
+			break
+		}
+	}
+	if !found {
+		return fmt.Errorf("peer %s not found", peerKey)
+	}
+
+	// remove the peer from the WireGuard configuration
+	peer := wgtypes.PeerConfig{
+		PublicKey: peerKeyParsed,
+		Remove:    true,
+	}
+
+	config := wgtypes.Config{
+		Peers: []wgtypes.PeerConfig{peer},
+	}
+	if ipcErr := c.device.IpcSet(toWgUserspaceString(config)); ipcErr != nil {
+		return fmt.Errorf("failed to remove peer: %s", ipcErr)
+	}
+
+	// Build the peer config
+	peer = wgtypes.PeerConfig{
+		PublicKey:         peerKeyParsed,
+		ReplaceAllowedIPs: true,
+		AllowedIPs:        allowedIPs,
+	}
+
+	config = wgtypes.Config{
+		Peers: []wgtypes.PeerConfig{peer},
+	}
+
+	if err := c.device.IpcSet(toWgUserspaceString(config)); err != nil {
+		return fmt.Errorf("remove endpoint address: %w", err)
+	}
+
+	return nil
+}
+
 func (c *WGUSPConfigurer) RemovePeer(peerKey string) error {
 	peerKeyParsed, err := wgtypes.ParseKey(peerKey)
 	if err != nil {
@@ -394,6 +455,13 @@ func toLastHandshake(stringVar string) (time.Time, error) {
 	if err != nil {
 		return time.Time{}, fmt.Errorf("parse handshake sec: %w", err)
 	}
+
+	// If sec is 0 (Unix epoch), return zero time instead
+	// This indicates no handshake has occurred
+	if sec == 0 {
+		return time.Time{}, nil
+	}
+
 	return time.Unix(sec, 0), nil
 }
 
@@ -402,7 +470,7 @@ func toBytes(s string) (int64, error) {
 }
 
 func getFwmark() int {
-	if nbnet.AdvancedRouting() {
+	if nbnet.AdvancedRouting() && runtime.GOOS == "linux" {
 		return nbnet.ControlPlaneMark
 	}
 	return 0

client/iface/device.go

@@ -7,19 +7,21 @@ import (
 
 	wgdevice "golang.zx2c4.com/wireguard/device"
 
-	"github.com/netbirdio/netbird/client/iface/bind"
 	"github.com/netbirdio/netbird/client/iface/device"
+	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 )
 
 type WGTunDevice interface {
 	Create() (device.WGConfigurer, error)
-	Up() (*bind.UniversalUDPMuxDefault, error)
+	Up() (*udpmux.UniversalUDPMuxDefault, error)
 	UpdateAddr(address wgaddr.Address) error
 	WgAddress() wgaddr.Address
+	MTU() uint16
 	DeviceName() string
 	Close() error
 	FilteredDevice() *device.FilteredDevice
 	Device() *wgdevice.Device
 	GetNet() *netstack.Net
+	GetICEBind() device.EndpointManager
 }

client/iface/device/device_android.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/netbirdio/netbird/client/iface/bind"
 	"github.com/netbirdio/netbird/client/iface/configurer"
+	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 )
 
@@ -21,7 +22,7 @@ type WGTunDevice struct {
 	address    wgaddr.Address
 	port       int
 	key        string
-	mtu        int
+	mtu        uint16
 	iceBind    *bind.ICEBind
 	tunAdapter TunAdapter
 	disableDNS bool
@@ -29,11 +30,11 @@ type WGTunDevice struct {
 	name           string
 	device         *device.Device
 	filteredDevice *FilteredDevice
-	udpMux         *bind.UniversalUDPMuxDefault
+	udpMux         *udpmux.UniversalUDPMuxDefault
 	configurer     WGConfigurer
 }
 
-func NewTunDevice(address wgaddr.Address, port int, key string, mtu int, iceBind *bind.ICEBind, tunAdapter TunAdapter, disableDNS bool) *WGTunDevice {
+func NewTunDevice(address wgaddr.Address, port int, key string, mtu uint16, iceBind *bind.ICEBind, tunAdapter TunAdapter, disableDNS bool) *WGTunDevice {
 	return &WGTunDevice{
 		address:    address,
 		port:       port,
@@ -58,7 +59,7 @@ func (t *WGTunDevice) Create(routes []string, dns string, searchDomains []string
 		searchDomainsToString = ""
 	}
 
-	fd, err := t.tunAdapter.ConfigureInterface(t.address.String(), t.mtu, dns, searchDomainsToString, routesString)
+	fd, err := t.tunAdapter.ConfigureInterface(t.address.String(), int(t.mtu), dns, searchDomainsToString, routesString)
 	if err != nil {
 		log.Errorf("failed to create Android interface: %s", err)
 		return nil, err
@@ -88,7 +89,7 @@ func (t *WGTunDevice) Create(routes []string, dns string, searchDomains []string
 	}
 	return t.configurer, nil
 }
-func (t *WGTunDevice) Up() (*bind.UniversalUDPMuxDefault, error) {
+func (t *WGTunDevice) Up() (*udpmux.UniversalUDPMuxDefault, error) {
 	err := t.device.Up()
 	if err != nil {
 		return nil, err
@@ -137,6 +138,10 @@ func (t *WGTunDevice) WgAddress() wgaddr.Address {
 	return t.address
 }
 
+func (t *WGTunDevice) MTU() uint16 {
+	return t.mtu
+}
+
 func (t *WGTunDevice) FilteredDevice() *FilteredDevice {
 	return t.filteredDevice
 }
@@ -145,6 +150,11 @@ func (t *WGTunDevice) GetNet() *netstack.Net {
 	return nil
 }
 
+// GetICEBind returns the ICEBind instance
+func (t *WGTunDevice) GetICEBind() EndpointManager {
+	return t.iceBind
+}
+
 func routesToString(routes []string) string {
 	return strings.Join(routes, ";")
 }

client/iface/device/device_darwin.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/netbirdio/netbird/client/iface/bind"
 	"github.com/netbirdio/netbird/client/iface/configurer"
+	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 )
 
@@ -21,16 +22,16 @@ type TunDevice struct {
 	address wgaddr.Address
 	port    int
 	key     string
-	mtu     int
+	mtu     uint16
 	iceBind *bind.ICEBind
 
 	device         *device.Device
 	filteredDevice *FilteredDevice
-	udpMux         *bind.UniversalUDPMuxDefault
+	udpMux         *udpmux.UniversalUDPMuxDefault
 	configurer     WGConfigurer
 }
 
-func NewTunDevice(name string, address wgaddr.Address, port int, key string, mtu int, iceBind *bind.ICEBind) *TunDevice {
+func NewTunDevice(name string, address wgaddr.Address, port int, key string, mtu uint16, iceBind *bind.ICEBind) *TunDevice {
 	return &TunDevice{
 		name:    name,
 		address: address,
@@ -42,7 +43,7 @@ func NewTunDevice(name string, address wgaddr.Address, port int, key string, mtu
 }
 
 func (t *TunDevice) Create() (WGConfigurer, error) {
-	tunDevice, err := tun.CreateTUN(t.name, t.mtu)
+	tunDevice, err := tun.CreateTUN(t.name, int(t.mtu))
 	if err != nil {
 		return nil, fmt.Errorf("error creating tun device: %s", err)
 	}
@@ -71,7 +72,7 @@ func (t *TunDevice) Create() (WGConfigurer, error) {
 	return t.configurer, nil
 }
 
-func (t *TunDevice) Up() (*bind.UniversalUDPMuxDefault, error) {
+func (t *TunDevice) Up() (*udpmux.UniversalUDPMuxDefault, error) {
 	err := t.device.Up()
 	if err != nil {
 		return nil, err
@@ -111,6 +112,10 @@ func (t *TunDevice) WgAddress() wgaddr.Address {
 	return t.address
 }
 
+func (t *TunDevice) MTU() uint16 {
+	return t.mtu
+}
+
 func (t *TunDevice) DeviceName() string {
 	return t.name
 }
@@ -149,3 +154,8 @@ func (t *TunDevice) assignAddr() error {
 func (t *TunDevice) GetNet() *netstack.Net {
 	return nil
 }
+
+// GetICEBind returns the ICEBind instance
+func (t *TunDevice) GetICEBind() EndpointManager {
+	return t.iceBind
+}

client/iface/device/device_ios.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/netbirdio/netbird/client/iface/bind"
 	"github.com/netbirdio/netbird/client/iface/configurer"
+	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 )
 
@@ -22,21 +23,23 @@ type TunDevice struct {
 	address wgaddr.Address
 	port    int
 	key     string
+	mtu     uint16
 	iceBind *bind.ICEBind
 	tunFd   int
 
 	device         *device.Device
 	filteredDevice *FilteredDevice
-	udpMux         *bind.UniversalUDPMuxDefault
+	udpMux         *udpmux.UniversalUDPMuxDefault
 	configurer     WGConfigurer
 }
 
-func NewTunDevice(name string, address wgaddr.Address, port int, key string, iceBind *bind.ICEBind, tunFd int) *TunDevice {
+func NewTunDevice(name string, address wgaddr.Address, port int, key string, mtu uint16, iceBind *bind.ICEBind, tunFd int) *TunDevice {
 	return &TunDevice{
 		name:    name,
 		address: address,
 		port:    port,
 		key:     key,
+		mtu:     mtu,
 		iceBind: iceBind,
 		tunFd:   tunFd,
 	}
@@ -81,7 +84,7 @@ func (t *TunDevice) Create() (WGConfigurer, error) {
 	return t.configurer, nil
 }
 
-func (t *TunDevice) Up() (*bind.UniversalUDPMuxDefault, error) {
+func (t *TunDevice) Up() (*udpmux.UniversalUDPMuxDefault, error) {
 	err := t.device.Up()
 	if err != nil {
 		return nil, err
@@ -125,6 +128,10 @@ func (t *TunDevice) WgAddress() wgaddr.Address {
 	return t.address
 }
 
+func (t *TunDevice) MTU() uint16 {
+	return t.mtu
+}
+
 func (t *TunDevice) UpdateAddr(_ wgaddr.Address) error {
 	// todo implement
 	return nil
@@ -137,3 +144,8 @@ func (t *TunDevice) FilteredDevice() *FilteredDevice {
 func (t *TunDevice) GetNet() *netstack.Net {
 	return nil
 }
+
+// GetICEBind returns the ICEBind instance
+func (t *TunDevice) GetICEBind() EndpointManager {
+	return t.iceBind
+}

client/iface/device/device_kernel_unix.go

@@ -12,11 +12,11 @@ import (
 	"golang.zx2c4.com/wireguard/device"
 	"golang.zx2c4.com/wireguard/tun/netstack"
 
-	"github.com/netbirdio/netbird/client/iface/bind"
 	"github.com/netbirdio/netbird/client/iface/configurer"
+	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
+	nbnet "github.com/netbirdio/netbird/client/net"
 	"github.com/netbirdio/netbird/sharedsock"
-	nbnet "github.com/netbirdio/netbird/util/net"
 )
 
 type TunKernelDevice struct {
@@ -24,19 +24,19 @@ type TunKernelDevice struct {
 	address      wgaddr.Address
 	wgPort       int
 	key          string
-	mtu          int
+	mtu          uint16
 	ctx          context.Context
 	ctxCancel    context.CancelFunc
 	transportNet transport.Net
 
 	link       *wgLink
 	udpMuxConn net.PacketConn
-	udpMux     *bind.UniversalUDPMuxDefault
+	udpMux     *udpmux.UniversalUDPMuxDefault
 
-	filterFn bind.FilterFn
+	filterFn udpmux.FilterFn
 }
 
-func NewKernelDevice(name string, address wgaddr.Address, wgPort int, key string, mtu int, transportNet transport.Net) *TunKernelDevice {
+func NewKernelDevice(name string, address wgaddr.Address, wgPort int, key string, mtu uint16, transportNet transport.Net) *TunKernelDevice {
 	ctx, cancel := context.WithCancel(context.Background())
 	return &TunKernelDevice{
 		ctx:          ctx,
@@ -66,7 +66,7 @@ func (t *TunKernelDevice) Create() (WGConfigurer, error) {
 	// TODO: do a MTU discovery
 	log.Debugf("setting MTU: %d interface: %s", t.mtu, t.name)
 
-	if err := link.setMTU(t.mtu); err != nil {
+	if err := link.setMTU(int(t.mtu)); err != nil {
 		return nil, fmt.Errorf("set mtu: %w", err)
 	}
 
@@ -79,7 +79,7 @@ func (t *TunKernelDevice) Create() (WGConfigurer, error) {
 	return configurer, nil
 }
 
-func (t *TunKernelDevice) Up() (*bind.UniversalUDPMuxDefault, error) {
+func (t *TunKernelDevice) Up() (*udpmux.UniversalUDPMuxDefault, error) {
 	if t.udpMux != nil {
 		return t.udpMux, nil
 	}
@@ -96,23 +96,19 @@ func (t *TunKernelDevice) Up() (*bind.UniversalUDPMuxDefault, error) {
 		return nil, err
 	}
 
-	rawSock, err := sharedsock.Listen(t.wgPort, sharedsock.NewIncomingSTUNFilter())
+	rawSock, err := sharedsock.Listen(t.wgPort, sharedsock.NewIncomingSTUNFilter(), t.mtu)
 	if err != nil {
 		return nil, err
 	}
 
-	var udpConn net.PacketConn = rawSock
-	if !nbnet.AdvancedRouting() {
-		udpConn = nbnet.WrapPacketConn(rawSock)
-	}
-
-	bindParams := bind.UniversalUDPMuxParams{
-		UDPConn:   udpConn,
+	bindParams := udpmux.UniversalUDPMuxParams{
+		UDPConn:   nbnet.WrapPacketConn(rawSock),
 		Net:       t.transportNet,
 		FilterFn:  t.filterFn,
 		WGAddress: t.address,
+		MTU:       t.mtu,
 	}
-	mux := bind.NewUniversalUDPMuxDefault(bindParams)
+	mux := udpmux.NewUniversalUDPMuxDefault(bindParams)
 	go mux.ReadFromConn(t.ctx)
 	t.udpMuxConn = rawSock
 	t.udpMux = mux
@@ -158,6 +154,10 @@ func (t *TunKernelDevice) WgAddress() wgaddr.Address {
 	return t.address
 }
 
+func (t *TunKernelDevice) MTU() uint16 {
+	return t.mtu
+}
+
 func (t *TunKernelDevice) DeviceName() string {
 	return t.name
 }
@@ -179,3 +179,8 @@ func (t *TunKernelDevice) assignAddr() error {
 func (t *TunKernelDevice) GetNet() *netstack.Net {
 	return nil
 }
+
+// GetICEBind returns nil for kernel mode devices
+func (t *TunKernelDevice) GetICEBind() EndpointManager {
+	return nil
+}

client/iface/device/device_netstack.go

@@ -1,41 +1,48 @@
-//go:build !android
-// +build !android
-
 package device
 
 import (
+	"errors"
 	"fmt"
 
 	log "github.com/sirupsen/logrus"
+	"golang.zx2c4.com/wireguard/conn"
 	"golang.zx2c4.com/wireguard/device"
 	"golang.zx2c4.com/wireguard/tun/netstack"
 
 	"github.com/netbirdio/netbird/client/iface/bind"
 	"github.com/netbirdio/netbird/client/iface/configurer"
 	nbnetstack "github.com/netbirdio/netbird/client/iface/netstack"
+	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
-	nbnet "github.com/netbirdio/netbird/util/net"
+	nbnet "github.com/netbirdio/netbird/client/net"
 )
 
+type Bind interface {
+	conn.Bind
+	GetICEMux() (*udpmux.UniversalUDPMuxDefault, error)
+	ActivityRecorder() *bind.ActivityRecorder
+	EndpointManager
+}
+
 type TunNetstackDevice struct {
 	name          string
 	address       wgaddr.Address
 	port          int
 	key           string
-	mtu           int
+	mtu           uint16
 	listenAddress string
-	iceBind       *bind.ICEBind
+	bind          Bind
 
 	device         *device.Device
 	filteredDevice *FilteredDevice
 	nsTun          *nbnetstack.NetStackTun
-	udpMux         *bind.UniversalUDPMuxDefault
+	udpMux         *udpmux.UniversalUDPMuxDefault
 	configurer     WGConfigurer
 
 	net *netstack.Net
 }
 
-func NewNetstackDevice(name string, address wgaddr.Address, wgPort int, key string, mtu int, iceBind *bind.ICEBind, listenAddress string) *TunNetstackDevice {
+func NewNetstackDevice(name string, address wgaddr.Address, wgPort int, key string, mtu uint16, bind Bind, listenAddress string) *TunNetstackDevice {
 	return &TunNetstackDevice{
 		name:          name,
 		address:       address,
@@ -43,11 +50,11 @@ func NewNetstackDevice(name string, address wgaddr.Address, wgPort int, key stri
 		key:           key,
 		mtu:           mtu,
 		listenAddress: listenAddress,
-		iceBind:       iceBind,
+		bind:          bind,
 	}
 }
 
-func (t *TunNetstackDevice) Create() (WGConfigurer, error) {
+func (t *TunNetstackDevice) create() (WGConfigurer, error) {
 	log.Info("create nbnetstack tun interface")
 
 	// TODO: get from service listener runtime IP
@@ -57,7 +64,7 @@ func (t *TunNetstackDevice) Create() (WGConfigurer, error) {
 	}
 
 	log.Debugf("netstack using address: %s", t.address.IP)
-	t.nsTun = nbnetstack.NewNetStackTun(t.listenAddress, t.address.IP, dnsAddr, t.mtu)
+	t.nsTun = nbnetstack.NewNetStackTun(t.listenAddress, t.address.IP, dnsAddr, int(t.mtu))
 	log.Debugf("netstack using dns address: %s", dnsAddr)
 	tunIface, net, err := t.nsTun.Create()
 	if err != nil {
@@ -68,11 +75,11 @@ func (t *TunNetstackDevice) Create() (WGConfigurer, error) {
 
 	t.device = device.NewDevice(
 		t.filteredDevice,
-		t.iceBind,
+		t.bind,
 		device.NewLogger(wgLogLevel(), "[netbird] "),
 	)
 
-	t.configurer = configurer.NewUSPConfigurer(t.device, t.name, t.iceBind.ActivityRecorder())
+	t.configurer = configurer.NewUSPConfigurer(t.device, t.name, t.bind.ActivityRecorder())
 	err = t.configurer.ConfigureInterface(t.key, t.port)
 	if err != nil {
 		_ = tunIface.Close()
@@ -83,7 +90,7 @@ func (t *TunNetstackDevice) Create() (WGConfigurer, error) {
 	return t.configurer, nil
 }
 
-func (t *TunNetstackDevice) Up() (*bind.UniversalUDPMuxDefault, error) {
+func (t *TunNetstackDevice) Up() (*udpmux.UniversalUDPMuxDefault, error) {
 	if t.device == nil {
 		return nil, fmt.Errorf("device is not ready yet")
 	}
@@ -93,11 +100,15 @@ func (t *TunNetstackDevice) Up() (*bind.UniversalUDPMuxDefault, error) {
 		return nil, err
 	}
 
-	udpMux, err := t.iceBind.GetICEMux()
-	if err != nil {
+	udpMux, err := t.bind.GetICEMux()
+	if err != nil && !errors.Is(err, bind.ErrUDPMUXNotSupported) {
 		return nil, err
 	}
-	t.udpMux = udpMux
+
+	if udpMux != nil {
+		t.udpMux = udpMux
+	}
+
 	log.Debugf("netstack device is ready to use")
 	return udpMux, nil
 }
@@ -125,6 +136,10 @@ func (t *TunNetstackDevice) WgAddress() wgaddr.Address {
 	return t.address
 }
 
+func (t *TunNetstackDevice) MTU() uint16 {
+	return t.mtu
+}
+
 func (t *TunNetstackDevice) DeviceName() string {
 	return t.name
 }
@@ -141,3 +156,8 @@ func (t *TunNetstackDevice) Device() *device.Device {
 func (t *TunNetstackDevice) GetNet() *netstack.Net {
 	return t.net
 }
+
+// GetICEBind returns the bind instance
+func (t *TunNetstackDevice) GetICEBind() EndpointManager {
+	return t.bind
+}

client/iface/device/device_netstack_android.go

@@ -0,0 +1,7 @@
+//go:build android
+
+package device
+
+func (t *TunNetstackDevice) Create(routes []string, dns string, searchDomains []string) (WGConfigurer, error) {
+	return t.create()
+}

client/iface/device/device_netstack_generic.go

@@ -0,0 +1,7 @@
+//go:build !android
+
+package device
+
+func (t *TunNetstackDevice) Create() (WGConfigurer, error) {
+	return t.create()
+}

client/iface/device/device_netstack_test.go

@@ -0,0 +1,27 @@
+package device
+
+import (
+	"testing"
+
+	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
+
+	"github.com/netbirdio/netbird/client/iface/bind"
+	"github.com/netbirdio/netbird/client/iface/netstack"
+	"github.com/netbirdio/netbird/client/iface/wgaddr"
+)
+
+func TestNewNetstackDevice(t *testing.T) {
+	privateKey, _ := wgtypes.GeneratePrivateKey()
+	wgAddress, _ := wgaddr.ParseWGAddress("1.2.3.4/24")
+
+	relayBind := bind.NewRelayBindJS()
+	nsTun := NewNetstackDevice("wtx", wgAddress, 1234, privateKey.String(), 1500, relayBind, netstack.ListenAddr())
+
+	cfgr, err := nsTun.Create()
+	if err != nil {
+		t.Fatalf("failed to create netstack device: %v", err)
+	}
+	if cfgr == nil {
+		t.Fatal("expected non-nil configurer")
+	}
+}

client/iface/device/device_usp_unix.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/netbirdio/netbird/client/iface/bind"
 	"github.com/netbirdio/netbird/client/iface/configurer"
+	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 )
 
@@ -20,16 +21,16 @@ type USPDevice struct {
 	address wgaddr.Address
 	port    int
 	key     string
-	mtu     int
+	mtu     uint16
 	iceBind *bind.ICEBind
 
 	device         *device.Device
 	filteredDevice *FilteredDevice
-	udpMux         *bind.UniversalUDPMuxDefault
+	udpMux         *udpmux.UniversalUDPMuxDefault
 	configurer     WGConfigurer
 }
 
-func NewUSPDevice(name string, address wgaddr.Address, port int, key string, mtu int, iceBind *bind.ICEBind) *USPDevice {
+func NewUSPDevice(name string, address wgaddr.Address, port int, key string, mtu uint16, iceBind *bind.ICEBind) *USPDevice {
 	log.Infof("using userspace bind mode")
 
 	return &USPDevice{
@@ -44,9 +45,9 @@ func NewUSPDevice(name string, address wgaddr.Address, port int, key string, mtu
 
 func (t *USPDevice) Create() (WGConfigurer, error) {
 	log.Info("create tun interface")
-	tunIface, err := tun.CreateTUN(t.name, t.mtu)
+	tunIface, err := tun.CreateTUN(t.name, int(t.mtu))
 	if err != nil {
-		log.Debugf("failed to create tun interface (%s, %d): %s", t.name, t.mtu, err)
+		log.Debugf("failed to create tun interface (%s, %d): %s", t.name, int(t.mtu), err)
 		return nil, fmt.Errorf("error creating tun device: %s", err)
 	}
 	t.filteredDevice = newDeviceFilter(tunIface)
@@ -74,7 +75,7 @@ func (t *USPDevice) Create() (WGConfigurer, error) {
 	return t.configurer, nil
 }
 
-func (t *USPDevice) Up() (*bind.UniversalUDPMuxDefault, error) {
+func (t *USPDevice) Up() (*udpmux.UniversalUDPMuxDefault, error) {
 	if t.device == nil {
 		return nil, fmt.Errorf("device is not ready yet")
 	}
@@ -118,6 +119,10 @@ func (t *USPDevice) WgAddress() wgaddr.Address {
 	return t.address
 }
 
+func (t *USPDevice) MTU() uint16 {
+	return t.mtu
+}
+
 func (t *USPDevice) DeviceName() string {
 	return t.name
 }
@@ -141,3 +146,8 @@ func (t *USPDevice) assignAddr() error {
 func (t *USPDevice) GetNet() *netstack.Net {
 	return nil
 }
+
+// GetICEBind returns the ICEBind instance
+func (t *USPDevice) GetICEBind() EndpointManager {
+	return t.iceBind
+}

client/iface/device/device_windows.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/netbirdio/netbird/client/iface/bind"
 	"github.com/netbirdio/netbird/client/iface/configurer"
+	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 )
 
@@ -23,17 +24,17 @@ type TunDevice struct {
 	address wgaddr.Address
 	port    int
 	key     string
-	mtu     int
+	mtu     uint16
 	iceBind *bind.ICEBind
 
 	device          *device.Device
 	nativeTunDevice *tun.NativeTun
 	filteredDevice  *FilteredDevice
-	udpMux          *bind.UniversalUDPMuxDefault
+	udpMux          *udpmux.UniversalUDPMuxDefault
 	configurer      WGConfigurer
 }
 
-func NewTunDevice(name string, address wgaddr.Address, port int, key string, mtu int, iceBind *bind.ICEBind) *TunDevice {
+func NewTunDevice(name string, address wgaddr.Address, port int, key string, mtu uint16, iceBind *bind.ICEBind) *TunDevice {
 	return &TunDevice{
 		name:    name,
 		address: address,
@@ -59,7 +60,7 @@ func (t *TunDevice) Create() (WGConfigurer, error) {
 		return nil, err
 	}
 	log.Info("create tun interface")
-	tunDevice, err := tun.CreateTUNWithRequestedGUID(t.name, &guid, t.mtu)
+	tunDevice, err := tun.CreateTUNWithRequestedGUID(t.name, &guid, int(t.mtu))
 	if err != nil {
 		return nil, fmt.Errorf("error creating tun device: %s", err)
 	}
@@ -104,7 +105,7 @@ func (t *TunDevice) Create() (WGConfigurer, error) {
 	return t.configurer, nil
 }
 
-func (t *TunDevice) Up() (*bind.UniversalUDPMuxDefault, error) {
+func (t *TunDevice) Up() (*udpmux.UniversalUDPMuxDefault, error) {
 	err := t.device.Up()
 	if err != nil {
 		return nil, err
@@ -144,6 +145,10 @@ func (t *TunDevice) WgAddress() wgaddr.Address {
 	return t.address
 }
 
+func (t *TunDevice) MTU() uint16 {
+	return t.mtu
+}
+
 func (t *TunDevice) DeviceName() string {
 	return t.name
 }
@@ -180,3 +185,8 @@ func (t *TunDevice) assignAddr() error {
 func (t *TunDevice) GetNet() *netstack.Net {
 	return nil
 }
+
+// GetICEBind returns the ICEBind instance
+func (t *TunDevice) GetICEBind() EndpointManager {
+	return t.iceBind
+}

client/iface/device/endpoint_manager.go

@@ -0,0 +1,13 @@
+package device
+
+import (
+	"net"
+	"net/netip"
+)
+
+// EndpointManager manages fake IP to connection mappings for userspace bind implementations.
+// Implemented by bind.ICEBind and bind.RelayBindJS.
+type EndpointManager interface {
+	SetEndpoint(fakeIP netip.Addr, conn net.Conn)
+	RemoveEndpoint(fakeIP netip.Addr)
+}

client/iface/device/interface.go

@@ -21,4 +21,5 @@ type WGConfigurer interface {
 	GetStats() (map[string]configurer.WGStats, error)
 	FullStats() (*configurer.Stats, error)
 	LastActivities() map[string]monotime.Time
+	RemoveEndpointAddress(peerKey string) error
 }

client/iface/device_android.go

@@ -5,19 +5,21 @@ import (
 
 	"golang.zx2c4.com/wireguard/tun/netstack"
 
-	"github.com/netbirdio/netbird/client/iface/bind"
 	"github.com/netbirdio/netbird/client/iface/device"
+	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 )
 
 type WGTunDevice interface {
 	Create(routes []string, dns string, searchDomains []string) (device.WGConfigurer, error)
-	Up() (*bind.UniversalUDPMuxDefault, error)
+	Up() (*udpmux.UniversalUDPMuxDefault, error)
 	UpdateAddr(address wgaddr.Address) error
 	WgAddress() wgaddr.Address
+	MTU() uint16
 	DeviceName() string
 	Close() error
 	FilteredDevice() *device.FilteredDevice
 	Device() *wgdevice.Device
 	GetNet() *netstack.Net
+	GetICEBind() device.EndpointManager
 }

client/iface/iface.go

@@ -16,9 +16,9 @@ import (
 	wgdevice "golang.zx2c4.com/wireguard/device"
 
 	"github.com/netbirdio/netbird/client/errors"
-	"github.com/netbirdio/netbird/client/iface/bind"
 	"github.com/netbirdio/netbird/client/iface/configurer"
 	"github.com/netbirdio/netbird/client/iface/device"
+	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 	"github.com/netbirdio/netbird/client/iface/wgproxy"
 	"github.com/netbirdio/netbird/monotime"
@@ -26,6 +26,8 @@ import (
 
 const (
 	DefaultMTU         = 1280
+	MinMTU             = 576
+	MaxMTU             = 8192
 	DefaultWgPort      = 51820
 	WgInterfaceDefault = configurer.WgInterfaceDefault
 )
@@ -35,6 +37,17 @@ var (
 	ErrIfaceNotFound = fmt.Errorf("wireguard interface not found")
 )
 
+// ValidateMTU validates that MTU is within acceptable range
+func ValidateMTU(mtu uint16) error {
+	if mtu < MinMTU {
+		return fmt.Errorf("MTU %d below minimum (%d bytes)", mtu, MinMTU)
+	}
+	if mtu > MaxMTU {
+		return fmt.Errorf("MTU %d exceeds maximum supported size (%d bytes)", mtu, MaxMTU)
+	}
+	return nil
+}
+
 type wgProxyFactory interface {
 	GetProxy() wgproxy.Proxy
 	Free() error
@@ -45,10 +58,10 @@ type WGIFaceOpts struct {
 	Address      string
 	WGPort       int
 	WGPrivKey    string
-	MTU          int
+	MTU          uint16
 	MobileArgs   *device.MobileIFaceArguments
 	TransportNet transport.Net
-	FilterFn     bind.FilterFn
+	FilterFn     udpmux.FilterFn
 	DisableDNS   bool
 }
 
@@ -67,6 +80,17 @@ func (w *WGIface) GetProxy() wgproxy.Proxy {
 	return w.wgProxyFactory.GetProxy()
 }
 
+// GetBind returns the EndpointManager userspace bind mode.
+func (w *WGIface) GetBind() device.EndpointManager {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	if w.tun == nil {
+		return nil
+	}
+	return w.tun.GetICEBind()
+}
+
 // IsUserspaceBind indicates whether this interfaces is userspace with bind.ICEBind
 func (w *WGIface) IsUserspaceBind() bool {
 	return w.userspaceBind
@@ -82,6 +106,10 @@ func (w *WGIface) Address() wgaddr.Address {
 	return w.tun.WgAddress()
 }
 
+func (w *WGIface) MTU() uint16 {
+	return w.tun.MTU()
+}
+
 // ToInterface returns the net.Interface for the Wireguard interface
 func (r *WGIface) ToInterface() *net.Interface {
 	name := r.tun.DeviceName()
@@ -97,7 +125,7 @@ func (r *WGIface) ToInterface() *net.Interface {
 
 // Up configures a Wireguard interface
 // The interface must exist before calling this method (e.g. call interface.Create() before)
-func (w *WGIface) Up() (*bind.UniversalUDPMuxDefault, error) {
+func (w *WGIface) Up() (*udpmux.UniversalUDPMuxDefault, error) {
 	w.mu.Lock()
 	defer w.mu.Unlock()
 
@@ -131,6 +159,17 @@ func (w *WGIface) UpdatePeer(peerKey string, allowedIps []netip.Prefix, keepAliv
 	return w.configurer.UpdatePeer(peerKey, allowedIps, keepAlive, endpoint, preSharedKey)
 }
 
+func (w *WGIface) RemoveEndpointAddress(peerKey string) error {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	if w.configurer == nil {
+		return ErrIfaceNotFound
+	}
+
+	log.Debugf("Removing endpoint address: %s", peerKey)
+	return w.configurer.RemoveEndpointAddress(peerKey)
+}
+
 // RemovePeer removes a Wireguard Peer from the interface iface
 func (w *WGIface) RemovePeer(peerKey string) error {
 	w.mu.Lock()

client/iface/iface_destroy_js.go

@@ -0,0 +1,6 @@
+package iface
+
+// Destroy is a no-op on WASM
+func (w *WGIface) Destroy() error {
+	return nil
+}

client/iface/iface_new_android.go

@@ -3,6 +3,7 @@ package iface
 import (
 	"github.com/netbirdio/netbird/client/iface/bind"
 	"github.com/netbirdio/netbird/client/iface/device"
+	"github.com/netbirdio/netbird/client/iface/netstack"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 	"github.com/netbirdio/netbird/client/iface/wgproxy"
 )
@@ -14,12 +15,21 @@ func NewWGIFace(opts WGIFaceOpts) (*WGIface, error) {
 		return nil, err
 	}
 
-	iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress)
+	iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress, opts.MTU)
+
+	if netstack.IsEnabled() {
+		wgIFace := &WGIface{
+			userspaceBind:  true,
+			tun:            device.NewNetstackDevice(opts.IFaceName, wgAddress, opts.WGPort, opts.WGPrivKey, opts.MTU, iceBind, netstack.ListenAddr()),
+			wgProxyFactory: wgproxy.NewUSPFactory(iceBind, opts.MTU),
+		}
+		return wgIFace, nil
+	}
 
 	wgIFace := &WGIface{
 		userspaceBind:  true,
 		tun:            device.NewTunDevice(wgAddress, opts.WGPort, opts.WGPrivKey, opts.MTU, iceBind, opts.MobileArgs.TunAdapter, opts.DisableDNS),
-		wgProxyFactory: wgproxy.NewUSPFactory(iceBind),
+		wgProxyFactory: wgproxy.NewUSPFactory(iceBind, opts.MTU),
 	}
 	return wgIFace, nil
 }

client/iface/iface_new_darwin.go

@@ -17,7 +17,7 @@ func NewWGIFace(opts WGIFaceOpts) (*WGIface, error) {
 		return nil, err
 	}
 
-	iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress)
+	iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress, opts.MTU)
 
 	var tun WGTunDevice
 	if netstack.IsEnabled() {
@@ -29,7 +29,7 @@ func NewWGIFace(opts WGIFaceOpts) (*WGIface, error) {
 	wgIFace := &WGIface{
 		userspaceBind:  true,
 		tun:            tun,
-		wgProxyFactory: wgproxy.NewUSPFactory(iceBind),
+		wgProxyFactory: wgproxy.NewUSPFactory(iceBind, opts.MTU),
 	}
 	return wgIFace, nil
 }

client/iface/iface_new_freebsd.go

@@ -0,0 +1,41 @@
+//go:build freebsd
+
+package iface
+
+import (
+	"fmt"
+
+	"github.com/netbirdio/netbird/client/iface/bind"
+	"github.com/netbirdio/netbird/client/iface/device"
+	"github.com/netbirdio/netbird/client/iface/netstack"
+	"github.com/netbirdio/netbird/client/iface/wgaddr"
+	"github.com/netbirdio/netbird/client/iface/wgproxy"
+)
+
+// NewWGIFace Creates a new WireGuard interface instance
+func NewWGIFace(opts WGIFaceOpts) (*WGIface, error) {
+	wgAddress, err := wgaddr.ParseWGAddress(opts.Address)
+	if err != nil {
+		return nil, err
+	}
+
+	wgIFace := &WGIface{}
+
+	if netstack.IsEnabled() {
+		iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress, opts.MTU)
+		wgIFace.tun = device.NewNetstackDevice(opts.IFaceName, wgAddress, opts.WGPort, opts.WGPrivKey, opts.MTU, iceBind, netstack.ListenAddr())
+		wgIFace.userspaceBind = true
+		wgIFace.wgProxyFactory = wgproxy.NewUSPFactory(iceBind, opts.MTU)
+		return wgIFace, nil
+	}
+
+	if device.ModuleTunIsLoaded() {
+		iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress, opts.MTU)
+		wgIFace.tun = device.NewUSPDevice(opts.IFaceName, wgAddress, opts.WGPort, opts.WGPrivKey, opts.MTU, iceBind)
+		wgIFace.userspaceBind = true
+		wgIFace.wgProxyFactory = wgproxy.NewUSPFactory(iceBind, opts.MTU)
+		return wgIFace, nil
+	}
+
+	return nil, fmt.Errorf("couldn't check or load tun module")
+}

client/iface/iface_new_ios.go

@@ -16,12 +16,12 @@ func NewWGIFace(opts WGIFaceOpts) (*WGIface, error) {
 		return nil, err
 	}
 
-	iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress)
+	iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress, opts.MTU)
 
 	wgIFace := &WGIface{
-		tun:            device.NewTunDevice(opts.IFaceName, wgAddress, opts.WGPort, opts.WGPrivKey, iceBind, opts.MobileArgs.TunFd),
+		tun:            device.NewTunDevice(opts.IFaceName, wgAddress, opts.WGPort, opts.WGPrivKey, opts.MTU, iceBind, opts.MobileArgs.TunFd),
 		userspaceBind:  true,
-		wgProxyFactory: wgproxy.NewUSPFactory(iceBind),
+		wgProxyFactory: wgproxy.NewUSPFactory(iceBind, opts.MTU),
 	}
 	return wgIFace, nil
 }

client/iface/iface_new_js.go

@@ -0,0 +1,27 @@
+package iface
+
+import (
+	"github.com/netbirdio/netbird/client/iface/bind"
+	"github.com/netbirdio/netbird/client/iface/device"
+	"github.com/netbirdio/netbird/client/iface/netstack"
+	"github.com/netbirdio/netbird/client/iface/wgaddr"
+	"github.com/netbirdio/netbird/client/iface/wgproxy"
+)
+
+// NewWGIFace creates a new WireGuard interface for WASM (always uses netstack mode)
+func NewWGIFace(opts WGIFaceOpts) (*WGIface, error) {
+	wgAddress, err := wgaddr.ParseWGAddress(opts.Address)
+	if err != nil {
+		return nil, err
+	}
+
+	relayBind := bind.NewRelayBindJS()
+
+	wgIface := &WGIface{
+		tun:            device.NewNetstackDevice(opts.IFaceName, wgAddress, opts.WGPort, opts.WGPrivKey, opts.MTU, relayBind, netstack.ListenAddr()),
+		userspaceBind:  true,
+		wgProxyFactory: wgproxy.NewUSPFactory(relayBind, opts.MTU),
+	}
+
+	return wgIface, nil
+}

client/iface/iface_new_linux.go

@@ -1,4 +1,4 @@
-//go:build (linux && !android) || freebsd
+//go:build linux && !android
 
 package iface
 
@@ -22,23 +22,23 @@ func NewWGIFace(opts WGIFaceOpts) (*WGIface, error) {
 	wgIFace := &WGIface{}
 
 	if netstack.IsEnabled() {
-		iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress)
+		iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress, opts.MTU)
 		wgIFace.tun = device.NewNetstackDevice(opts.IFaceName, wgAddress, opts.WGPort, opts.WGPrivKey, opts.MTU, iceBind, netstack.ListenAddr())
 		wgIFace.userspaceBind = true
-		wgIFace.wgProxyFactory = wgproxy.NewUSPFactory(iceBind)
+		wgIFace.wgProxyFactory = wgproxy.NewUSPFactory(iceBind, opts.MTU)
 		return wgIFace, nil
 	}
 
 	if device.WireGuardModuleIsLoaded() {
 		wgIFace.tun = device.NewKernelDevice(opts.IFaceName, wgAddress, opts.WGPort, opts.WGPrivKey, opts.MTU, opts.TransportNet)
-		wgIFace.wgProxyFactory = wgproxy.NewKernelFactory(opts.WGPort)
+		wgIFace.wgProxyFactory = wgproxy.NewKernelFactory(opts.WGPort, opts.MTU)
 		return wgIFace, nil
 	}
 	if device.ModuleTunIsLoaded() {
-		iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress)
+		iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress, opts.MTU)
 		wgIFace.tun = device.NewUSPDevice(opts.IFaceName, wgAddress, opts.WGPort, opts.WGPrivKey, opts.MTU, iceBind)
 		wgIFace.userspaceBind = true
-		wgIFace.wgProxyFactory = wgproxy.NewUSPFactory(iceBind)
+		wgIFace.wgProxyFactory = wgproxy.NewUSPFactory(iceBind, opts.MTU)
 		return wgIFace, nil
 	}
 

client/iface/iface_new_windows.go

@@ -14,7 +14,7 @@ func NewWGIFace(opts WGIFaceOpts) (*WGIface, error) {
 	if err != nil {
 		return nil, err
 	}
-	iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress)
+	iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress, opts.MTU)
 
 	var tun WGTunDevice
 	if netstack.IsEnabled() {
@@ -26,7 +26,7 @@ func NewWGIFace(opts WGIFaceOpts) (*WGIface, error) {
 	wgIFace := &WGIface{
 		userspaceBind:  true,
 		tun:            tun,
-		wgProxyFactory: wgproxy.NewUSPFactory(iceBind),
+		wgProxyFactory: wgproxy.NewUSPFactory(iceBind, opts.MTU),
 	}
 	return wgIFace, nil
 

client/iface/netstack/env.go

@@ -1,3 +1,5 @@
+//go:build !js
+
 package netstack
 
 import (

client/iface/netstack/env_js.go

@@ -0,0 +1,12 @@
+package netstack
+
+const EnvUseNetstackMode = "NB_USE_NETSTACK_MODE"
+
+// IsEnabled always returns true for js since it's the only mode available
+func IsEnabled() bool {
+	return true
+}
+
+func ListenAddr() string {
+	return ""
+}

client/iface/udpmux/conn.go

@@ -1,4 +1,4 @@
-package bind
+package udpmux
 
 /*
  Most of this code was copied from https://github.com/pion/ice and modified to fulfill NetBird's requirements
@@ -16,11 +16,12 @@ import (
 )
 
 type udpMuxedConnParams struct {
-	Mux       *UDPMuxDefault
-	AddrPool  *sync.Pool
-	Key       string
-	LocalAddr net.Addr
-	Logger    logging.LeveledLogger
+	Mux         *SingleSocketUDPMux
+	AddrPool    *sync.Pool
+	Key         string
+	LocalAddr   net.Addr
+	Logger      logging.LeveledLogger
+	CandidateID string
 }
 
 // udpMuxedConn represents a logical packet conn for a single remote as identified by ufrag
@@ -119,6 +120,10 @@ func (c *udpMuxedConn) Close() error {
 	return err
 }
 
+func (c *udpMuxedConn) GetCandidateID() string {
+	return c.params.CandidateID
+}
+
 func (c *udpMuxedConn) isClosed() bool {
 	select {
 	case <-c.closedChan:

client/iface/udpmux/doc.go

@@ -0,0 +1,64 @@
+// Package udpmux provides a custom implementation of a UDP multiplexer
+// that allows multiple logical ICE connections to share a single underlying
+// UDP socket. This is based on Pion's ICE library, with modifications for
+// NetBird's requirements.
+//
+// # Background
+//
+// In WebRTC and NAT traversal scenarios, ICE (Interactive Connectivity
+// Establishment) is responsible for discovering candidate network paths
+// and maintaining connectivity between peers. Each ICE connection
+// normally requires a dedicated UDP socket. However, using one socket
+// per candidate can be inefficient and difficult to manage.
+//
+// This package introduces SingleSocketUDPMux, which allows multiple ICE
+// candidate connections (muxed connections) to share a single UDP socket.
+// It handles demultiplexing of packets based on ICE ufrag values, STUN
+// attributes, and candidate IDs.
+//
+// # Usage
+//
+// The typical flow is:
+//
+//  1. Create a UDP socket (net.PacketConn).
+//  2. Construct Params with the socket and optional logger/net stack.
+//  3. Call NewSingleSocketUDPMux(params).
+//  4. For each ICE candidate ufrag, call GetConn(ufrag, addr, candidateID)
+//     to obtain a logical PacketConn.
+//  5. Use the returned PacketConn just like a normal UDP connection.
+//
+// # STUN Message Routing Logic
+//
+//		When a STUN packet arrives, the mux decides which connection should
+//		receive it using this routing logic:
+//
+//		Primary Routing: Candidate Pair ID
+//		  - Extract the candidate pair ID from the STUN message using
+//		    ice.CandidatePairIDFromSTUN(msg)
+//	   - The target candidate is the locally generated candidate that
+//	     corresponds to the connection that should handle this STUN message
+//		  - If found, use the target candidate ID to lookup the specific
+//		    connection in candidateConnMap
+//		  - Route the message directly to that connection
+//
+//		Fallback Routing: Broadcasting
+//		  When candidate pair ID is not available or lookup fails:
+//		  - Collect connections from addressMap based on source address
+//		  - Find connection using username attribute (ufrag) from STUN message
+//		  - Remove duplicate connections from the list
+//		  - Send the STUN message to all collected connections
+//
+// # Peer Reflexive Candidate Discovery
+//
+//	When a remote peer sends a STUN message from an unknown source address
+//	(from a candidate that has not been exchanged via signal), the ICE
+//	library will:
+//	  - Generate a new peer reflexive candidate for this source address
+//	  - Extract or assign a candidate ID based on the STUN message attributes
+//	  - Create a mapping between the new peer reflexive candidate ID and
+//	    the appropriate local connection
+//
+//	This discovery mechanism ensures that STUN messages from newly discovered
+//	peer reflexive candidates can be properly routed to the correct local
+//	connection without requiring fallback broadcasting.
+package udpmux

client/iface/udpmux/mux.go

@@ -1,4 +1,4 @@
-package bind
+package udpmux
 
 import (
 	"fmt"
@@ -8,9 +8,9 @@ import (
 	"strings"
 	"sync"
 
-	"github.com/pion/ice/v3"
+	"github.com/pion/ice/v4"
 	"github.com/pion/logging"
-	"github.com/pion/stun/v2"
+	"github.com/pion/stun/v3"
 	"github.com/pion/transport/v3"
 	"github.com/pion/transport/v3/stdnet"
 	log "github.com/sirupsen/logrus"
@@ -22,9 +22,9 @@ import (
 
 const receiveMTU = 8192
 
-// UDPMuxDefault is an implementation of the interface
-type UDPMuxDefault struct {
-	params UDPMuxParams
+// SingleSocketUDPMux is an implementation of the interface
+type SingleSocketUDPMux struct {
+	params Params
 
 	closedChan chan struct{}
 	closeOnce  sync.Once
@@ -32,6 +32,9 @@ type UDPMuxDefault struct {
 	// connsIPv4 and connsIPv6 are maps of all udpMuxedConn indexed by ufrag|network|candidateType
 	connsIPv4, connsIPv6 map[string]*udpMuxedConn
 
+	// candidateConnMap maps local candidate IDs to their corresponding connection.
+	candidateConnMap map[string]*udpMuxedConn
+
 	addressMapMu sync.RWMutex
 	addressMap   map[string][]*udpMuxedConn
 
@@ -46,8 +49,8 @@ type UDPMuxDefault struct {
 
 const maxAddrSize = 512
 
-// UDPMuxParams are parameters for UDPMux.
-type UDPMuxParams struct {
+// Params are parameters for UDPMux.
+type Params struct {
 	Logger  logging.LeveledLogger
 	UDPConn net.PacketConn
 
@@ -147,18 +150,19 @@ func isZeros(ip net.IP) bool {
 	return true
 }
 
-// NewUDPMuxDefault creates an implementation of UDPMux
-func NewUDPMuxDefault(params UDPMuxParams) *UDPMuxDefault {
+// NewSingleSocketUDPMux creates an implementation of UDPMux
+func NewSingleSocketUDPMux(params Params) *SingleSocketUDPMux {
 	if params.Logger == nil {
 		params.Logger = getLogger()
 	}
 
-	mux := &UDPMuxDefault{
-		addressMap: map[string][]*udpMuxedConn{},
-		params:     params,
-		connsIPv4:  make(map[string]*udpMuxedConn),
-		connsIPv6:  make(map[string]*udpMuxedConn),
-		closedChan: make(chan struct{}, 1),
+	mux := &SingleSocketUDPMux{
+		addressMap:       map[string][]*udpMuxedConn{},
+		params:           params,
+		connsIPv4:        make(map[string]*udpMuxedConn),
+		connsIPv6:        make(map[string]*udpMuxedConn),
+		candidateConnMap: make(map[string]*udpMuxedConn),
+		closedChan:       make(chan struct{}, 1),
 		pool: &sync.Pool{
 			New: func() interface{} {
 				// big enough buffer to fit both packet and address
@@ -171,15 +175,15 @@ func NewUDPMuxDefault(params UDPMuxParams) *UDPMuxDefault {
 	return mux
 }
 
-func (m *UDPMuxDefault) updateLocalAddresses() {
+func (m *SingleSocketUDPMux) updateLocalAddresses() {
 	var localAddrsForUnspecified []net.Addr
 	if addr, ok := m.params.UDPConn.LocalAddr().(*net.UDPAddr); !ok {
 		m.params.Logger.Errorf("LocalAddr is not a net.UDPAddr, got %T", m.params.UDPConn.LocalAddr())
 	} else if ok && addr.IP.IsUnspecified() {
 		// For unspecified addresses, the correct behavior is to return errListenUnspecified, but
 		// it will break the applications that are already using unspecified UDP connection
-		// with UDPMuxDefault, so print a warn log and create a local address list for mux.
-		m.params.Logger.Warn("UDPMuxDefault should not listening on unspecified address, use NewMultiUDPMuxFromPort instead")
+		// with SingleSocketUDPMux, so print a warn log and create a local address list for mux.
+		m.params.Logger.Warn("SingleSocketUDPMux should not listening on unspecified address, use NewMultiUDPMuxFromPort instead")
 		var networks []ice.NetworkType
 		switch {
 
@@ -216,13 +220,13 @@ func (m *UDPMuxDefault) updateLocalAddresses() {
 	m.mu.Unlock()
 }
 
-// LocalAddr returns the listening address of this UDPMuxDefault
-func (m *UDPMuxDefault) LocalAddr() net.Addr {
+// LocalAddr returns the listening address of this SingleSocketUDPMux
+func (m *SingleSocketUDPMux) LocalAddr() net.Addr {
 	return m.params.UDPConn.LocalAddr()
 }
 
 // GetListenAddresses returns the list of addresses that this mux is listening on
-func (m *UDPMuxDefault) GetListenAddresses() []net.Addr {
+func (m *SingleSocketUDPMux) GetListenAddresses() []net.Addr {
 	m.updateLocalAddresses()
 
 	m.mu.Lock()
@@ -236,7 +240,7 @@ func (m *UDPMuxDefault) GetListenAddresses() []net.Addr {
 
 // GetConn returns a PacketConn given the connection's ufrag and network address
 // creates the connection if an existing one can't be found
-func (m *UDPMuxDefault) GetConn(ufrag string, addr net.Addr) (net.PacketConn, error) {
+func (m *SingleSocketUDPMux) GetConn(ufrag string, addr net.Addr, candidateID string) (net.PacketConn, error) {
 	// don't check addr for mux using unspecified address
 	m.mu.Lock()
 	lenLocalAddrs := len(m.localAddrsForUnspecified)
@@ -260,12 +264,14 @@ func (m *UDPMuxDefault) GetConn(ufrag string, addr net.Addr) (net.PacketConn, er
 		return conn, nil
 	}
 
-	c := m.createMuxedConn(ufrag)
+	c := m.createMuxedConn(ufrag, candidateID)
 	go func() {
 		<-c.CloseChannel()
 		m.RemoveConnByUfrag(ufrag)
 	}()
 
+	m.candidateConnMap[candidateID] = c
+
 	if isIPv6 {
 		m.connsIPv6[ufrag] = c
 	} else {
@@ -276,7 +282,7 @@ func (m *UDPMuxDefault) GetConn(ufrag string, addr net.Addr) (net.PacketConn, er
 }
 
 // RemoveConnByUfrag stops and removes the muxed packet connection
-func (m *UDPMuxDefault) RemoveConnByUfrag(ufrag string) {
+func (m *SingleSocketUDPMux) RemoveConnByUfrag(ufrag string) {
 	removedConns := make([]*udpMuxedConn, 0, 2)
 
 	// Keep lock section small to avoid deadlock with conn lock
@@ -284,10 +290,12 @@ func (m *UDPMuxDefault) RemoveConnByUfrag(ufrag string) {
 	if c, ok := m.connsIPv4[ufrag]; ok {
 		delete(m.connsIPv4, ufrag)
 		removedConns = append(removedConns, c)
+		delete(m.candidateConnMap, c.GetCandidateID())
 	}
 	if c, ok := m.connsIPv6[ufrag]; ok {
 		delete(m.connsIPv6, ufrag)
 		removedConns = append(removedConns, c)
+		delete(m.candidateConnMap, c.GetCandidateID())
 	}
 	m.mu.Unlock()
 
@@ -314,7 +322,7 @@ func (m *UDPMuxDefault) RemoveConnByUfrag(ufrag string) {
 }
 
 // IsClosed returns true if the mux had been closed
-func (m *UDPMuxDefault) IsClosed() bool {
+func (m *SingleSocketUDPMux) IsClosed() bool {
 	select {
 	case <-m.closedChan:
 		return true
@@ -324,7 +332,7 @@ func (m *UDPMuxDefault) IsClosed() bool {
 }
 
 // Close the mux, no further connections could be created
-func (m *UDPMuxDefault) Close() error {
+func (m *SingleSocketUDPMux) Close() error {
 	var err error
 	m.closeOnce.Do(func() {
 		m.mu.Lock()
@@ -347,11 +355,11 @@ func (m *UDPMuxDefault) Close() error {
 	return err
 }
 
-func (m *UDPMuxDefault) writeTo(buf []byte, rAddr net.Addr) (n int, err error) {
+func (m *SingleSocketUDPMux) writeTo(buf []byte, rAddr net.Addr) (n int, err error) {
 	return m.params.UDPConn.WriteTo(buf, rAddr)
 }
 
-func (m *UDPMuxDefault) registerConnForAddress(conn *udpMuxedConn, addr string) {
+func (m *SingleSocketUDPMux) registerConnForAddress(conn *udpMuxedConn, addr string) {
 	if m.IsClosed() {
 		return
 	}
@@ -368,81 +376,109 @@ func (m *UDPMuxDefault) registerConnForAddress(conn *udpMuxedConn, addr string)
 	log.Debugf("ICE: registered %s for %s", addr, conn.params.Key)
 }
 
-func (m *UDPMuxDefault) createMuxedConn(key string) *udpMuxedConn {
+func (m *SingleSocketUDPMux) createMuxedConn(key string, candidateID string) *udpMuxedConn {
 	c := newUDPMuxedConn(&udpMuxedConnParams{
-		Mux:       m,
-		Key:       key,
-		AddrPool:  m.pool,
-		LocalAddr: m.LocalAddr(),
-		Logger:    m.params.Logger,
+		Mux:         m,
+		Key:         key,
+		AddrPool:    m.pool,
+		LocalAddr:   m.LocalAddr(),
+		Logger:      m.params.Logger,
+		CandidateID: candidateID,
 	})
 	return c
 }
 
 // HandleSTUNMessage handles STUN packets and forwards them to underlying pion/ice library
-func (m *UDPMuxDefault) HandleSTUNMessage(msg *stun.Message, addr net.Addr) error {
-
+func (m *SingleSocketUDPMux) HandleSTUNMessage(msg *stun.Message, addr net.Addr) error {
 	remoteAddr, ok := addr.(*net.UDPAddr)
 	if !ok {
 		return fmt.Errorf("underlying PacketConn did not return a UDPAddr")
 	}
 
-	// If we have already seen this address dispatch to the appropriate destination
-	// If you are using the same socket for the Host and SRFLX candidates, it might be that there are more than one
-	// muxed connection - one for the SRFLX candidate and the other one for the HOST one.
-	// We will then forward STUN packets to each of these connections.
-	m.addressMapMu.RLock()
+	// Try to route to specific candidate connection first
+	if conn := m.findCandidateConnection(msg); conn != nil {
+		return conn.writePacket(msg.Raw, remoteAddr)
+	}
+
+	// Fallback: route to all possible connections
+	return m.forwardToAllConnections(msg, addr, remoteAddr)
+}
+
+// findCandidateConnection attempts to find the specific connection for a STUN message
+func (m *SingleSocketUDPMux) findCandidateConnection(msg *stun.Message) *udpMuxedConn {
+	candidatePairID, ok, err := ice.CandidatePairIDFromSTUN(msg)
+	if err != nil {
+		return nil
+	} else if !ok {
+		return nil
+	}
+
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	conn, exists := m.candidateConnMap[candidatePairID.TargetCandidateID()]
+	if !exists {
+		return nil
+	}
+	return conn
+}
+
+// forwardToAllConnections forwards STUN message to all relevant connections
+func (m *SingleSocketUDPMux) forwardToAllConnections(msg *stun.Message, addr net.Addr, remoteAddr *net.UDPAddr) error {
 	var destinationConnList []*udpMuxedConn
+
+	// Add connections from address map
+	m.addressMapMu.RLock()
 	if storedConns, ok := m.addressMap[addr.String()]; ok {
 		destinationConnList = append(destinationConnList, storedConns...)
 	}
 	m.addressMapMu.RUnlock()
 
-	var isIPv6 bool
-	if udpAddr, _ := addr.(*net.UDPAddr); udpAddr != nil && udpAddr.IP.To4() == nil {
-		isIPv6 = true
+	if conn, ok := m.findConnectionByUsername(msg, addr); ok {
+		// If we have already seen this address dispatch to the appropriate destination
+		// If you are using the same socket for the Host and SRFLX candidates, it might be that there are more than one
+		// muxed connection - one for the SRFLX candidate and the other one for the HOST one.
+		// We will then forward STUN packets to each of these connections.
+		if !m.connectionExists(conn, destinationConnList) {
+			destinationConnList = append(destinationConnList, conn)
+		}
 	}
 
-	// This block is needed to discover Peer Reflexive Candidates for which we don't know the Endpoint upfront.
-	// However, we can take a username attribute from the STUN message which contains ufrag.
-	// We can use ufrag to identify the destination conn to route packet to.
-	attr, stunAttrErr := msg.Get(stun.AttrUsername)
-	if stunAttrErr == nil {
-		ufrag := strings.Split(string(attr), ":")[0]
-
-		m.mu.Lock()
-		destinationConn := m.connsIPv4[ufrag]
-		if isIPv6 {
-			destinationConn = m.connsIPv6[ufrag]
-		}
-
-		if destinationConn != nil {
-			exists := false
-			for _, conn := range destinationConnList {
-				if conn.params.Key == destinationConn.params.Key {
-					exists = true
-					break
-				}
-			}
-			if !exists {
-				destinationConnList = append(destinationConnList, destinationConn)
-			}
-		}
-		m.mu.Unlock()
-	}
-
-	// Forward STUN packets to each destination connections even thought the STUN packet might not belong there.
-	// It will be discarded by the further ICE candidate logic if so.
+	// Forward to all found connections
 	for _, conn := range destinationConnList {
 		if err := conn.writePacket(msg.Raw, remoteAddr); err != nil {
 			log.Errorf("could not write packet: %v", err)
 		}
 	}
-
 	return nil
 }
 
-func (m *UDPMuxDefault) getConn(ufrag string, isIPv6 bool) (val *udpMuxedConn, ok bool) {
+// findConnectionByUsername finds connection using username attribute from STUN message
+func (m *SingleSocketUDPMux) findConnectionByUsername(msg *stun.Message, addr net.Addr) (*udpMuxedConn, bool) {
+	attr, err := msg.Get(stun.AttrUsername)
+	if err != nil {
+		return nil, false
+	}
+
+	ufrag := strings.Split(string(attr), ":")[0]
+	isIPv6 := isIPv6Address(addr)
+
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	return m.getConn(ufrag, isIPv6)
+}
+
+// connectionExists checks if a connection already exists in the list
+func (m *SingleSocketUDPMux) connectionExists(target *udpMuxedConn, conns []*udpMuxedConn) bool {
+	for _, conn := range conns {
+		if conn.params.Key == target.params.Key {
+			return true
+		}
+	}
+	return false
+}
+
+func (m *SingleSocketUDPMux) getConn(ufrag string, isIPv6 bool) (val *udpMuxedConn, ok bool) {
 	if isIPv6 {
 		val, ok = m.connsIPv6[ufrag]
 	} else {
@@ -451,6 +487,13 @@ func (m *UDPMuxDefault) getConn(ufrag string, isIPv6 bool) (val *udpMuxedConn, o
 	return
 }
 
+func isIPv6Address(addr net.Addr) bool {
+	if udpAddr, ok := addr.(*net.UDPAddr); ok {
+		return udpAddr.IP.To4() == nil
+	}
+	return false
+}
+
 type bufferHolder struct {
 	buf []byte
 }