[GH-ISSUE #4396] IP routing fails with flannel interface #8608

New Issue

saavagebueno · 2026-08-05T01:18:50-04:00

saavagebueno commented

2026-08-05 01:18:50 -04:00

Originally created by @Alemiz112 on GitHub (Aug 23, 2025).
Original GitHub issue: https://github.com/netbirdio/netbird/issues/4396

Some interfaces such as flannel have . in the name (flannel.1) and the associated /proc/sys/net/ipv4/conf/ is actually called flannel.1 rather than flannel/1.

This causes issues when Netbird client tries to set up server advertised routes.

The client shows following error:

2025-08-23T21:07:50Z ERRO client/internal/routemanager/systemops/systemops_linux.go:124: Error setting up sysctl: 1 error occurred:
	* read sysctl net.ipv4.conf.flannel.1.rp_filter: open /proc/sys/net/ipv4/conf/flannel/1/rp_filter: no such file or directory

I have been able to trace this to the following code that is responsible for resolving the rp_filter in directory named after the interface: link

My understanding is that this issue is causing client to fail configuring advanced routing, which as a result causes routes advertised by management/server not to work.

My environment
I am testing in kubernetes RKE2 environment with latest Netbird client running in a container/pod with privileged access with hostNetwork: true enabled. The host has a flannel interface flannel.1, which is part of the kubernetes stack.

Originally created by @Alemiz112 on GitHub (Aug 23, 2025). Original GitHub issue: https://github.com/netbirdio/netbird/issues/4396 Some interfaces such as flannel have `.` in the name (`flannel.1`) and the associated `/proc/sys/net/ipv4/conf/` is actually called `flannel.1` rather than `flannel/1`. This causes issues when Netbird client tries to set up server advertised routes. The client shows following error: ``` 2025-08-23T21:07:50Z ERRO client/internal/routemanager/systemops/systemops_linux.go:124: Error setting up sysctl: 1 error occurred: * read sysctl net.ipv4.conf.flannel.1.rp_filter: open /proc/sys/net/ipv4/conf/flannel/1/rp_filter: no such file or directory ``` I have been able to trace this to the following code that is responsible for resolving the `rp_filter` in directory named after the interface: [link](https://github.com/netbirdio/netbird/blob/5e273c121ac207ed36ca5367ff70eeeb056cc6cd/client/internal/routemanager/sysctl/sysctl_linux.go#L73) My understanding is that this issue is causing client to fail configuring advanced routing, which as a result causes routes advertised by management/server not to work. **My environment** I am testing in kubernetes RKE2 environment with latest Netbird client running in a container/pod with `privileged` access with `hostNetwork: true` enabled. The host has a flannel interface `flannel.1`, which is part of the kubernetes stack.

saavagebueno added the triage-needed label 2026-08-05 01:18:50 -04:00

saavagebueno closed this issue

2026-08-05 01:18:50 -04:00

saavagebueno commented

2026-08-05 01:18:50 -04:00

@dyumin commented on GitHub (Aug 27, 2025):

same problem on keenetic

@dyumin commented on GitHub (Aug 27, 2025): same problem on keenetic

saavagebueno commented

2026-08-05 01:18:50 -04:00

@stefan-fast commented on GitHub (Jul 18, 2026):

Still relevant in the newest version v0.74.7 unfortunately.

@stefan-fast commented on GitHub (Jul 18, 2026): Still relevant in the newest version `v0.74.7` unfortunately.

Sign in to join this conversation.

Branches Tags

main

claude/agent-network-test-cases-p743vw

android/gui-integration

revert/component-types

feat-post_quantum_ml_kem

ice-stun-wg-demux

dependabot/npm_and_yarn/proxy/web/npm_and_yarn-b39864987c

agent-network-setup-poc

dependabot/go_modules/aws-sdk-8f849ebaed

dependabot/github_actions/actions-a940c7c866

dependabot/go_modules/otel-e34c790afd

dependabot/go_modules/testcontainers-de325c0dd6

dependabot/go_modules/wireguard-dbd6b95108

dependabot/go_modules/pion-5f703e1eca

dependabot/go_modules/gorm-2271c8195b

fix-login-needed-check

dependabot/go_modules/google.golang.org/grpc-1.82.1

fix/ui-gtk3-support

enterprise-traefik-and-migration-fixes

disambiguate_p2p_metrics

revert/component-types-hookup

embedded-vnc

feature/ios-ssh

docs/agent-network-docs-update

dependabot/go_modules/github.com/aws/aws-sdk-go-v2/service/s3-1.106.3

dependabot/go_modules/github.com/pion/stun/v3-3.1.5

fix-ssh-authorized-users-multi-rule

peer-acl-multi-source

reverse-proxy-crowdsec-appsec

reverse-proxy-allow-match-or

client-local-metrics

lazy-conn-per-peer

lazy-conn-rosenpass

dependabot/go_modules/github.com/gopacket/gopacket-1.7.0

dependabot/go_modules/goauthentik.io/api/v3-3.2026050.6

dependabot/go_modules/github.com/pires/go-proxyproto-0.15.0

dependabot/go_modules/github.com/jackc/pgx/v5-5.10.0

dependabot/go_modules/github.com/oapi-codegen/runtime-1.6.0

dependabot/go_modules/github.com/eko/gocache/lib/v4-4.2.4

dependabot/go_modules/github.com/pkg/sftp-1.13.11

dependabot/go_modules/github.com/coreos/go-oidc/v3-3.20.0

ssh-windows-privilege-check

fix/explicit-cors-handling

fix/remove-math-rand

test/gui-memory-leak-fix

fix/ui-status-dispatch

install-script-ui-dependencies

fix/grpc-get-network-map

fix/subscribe-status-coalesce

fix/tray-menu-item-leak

fix/windows-tray-race

feature/changeset

worktree-dns-route-qtype-fallthrough

mdm_integration

mlsmaycon-patch-2

feat/agent-network-ollama

proxy-tunnel-cache-ttl-env

coderabbitai/utg/1e5b0a5

grpc-acl

test/battery-drain

components-impl-drop-indexes-use-xids-no-resource-policy-map

fix/nmap-relevant-groups

e2e-guardrail-blocks-unselected-model

fix/lazyconn-cold-start-allowed-ips

vertex-guardrails-model-access-e2e

add-atomic-cache-ops

refactor/relay-foreign-cache

ci/trigger-release-tests

feature/kimi-3-agent-networks-dns-warmup

feature/dns-lazy-conn-warmup

daemon-ipc-acl

feature/ui-translation-key-parity-check

refactor/relay-foreign-cache-tests

fix/lazyconn-idle-keep-wg-peer

dmitri-propagate-auth-grant-types-on-combined

0.74.7-branch

diagnose-empty-vs-corrupt-state

windows-sleep-detector

fix/cli-up-wait-for-daemon

rp_key_persistency

feature/native-grpc

0.74.6-branch

0.74.6-branch-sync

0.74.5-branch-sync

0.74.4-branch

fix/remove-stale-peers-removal

fix/remove-stale-proxy-logic

fix/nsis-preserve-autostart-on-upgrade

refactor/peer-event-bus

dependabot/go_modules/goauthentik.io/api/v3-3.2026050.3

dependabot/go_modules/github.com/pkg/sftp-1.13.10

components-impl-drop-indexes

fix-reset-aggregation-window-flake

dependabot/go_modules/github.com/pion/dtls/v3-3.1.5

0.74.x

fix/relay-states-lock

update-process-pkg

update-gopsutil-v4

fix/relay_states_lock

increase-sysinfo-timeout

dependabot/go_modules/github.com/Azure/go-ntlmssp-0.1.1

dependabot/go_modules/github.com/eko/gocache/store/redis/v4-4.2.6

dependabot/go_modules/github.com/eko/gocache/lib/v4-4.2.3

fix/fail-to-create-upnp-port-mapping-on-opnsense-firewall

0.74.3-branch

fix/routeselector-atomic-exit-node

netmap_progressive_alignment

nmap/components-impl

dependabot/go_modules/github.com/jackc/pgx/v5-5.9.2

dependabot/go_modules/github.com/oapi-codegen/runtime-1.4.2

dependabot/go_modules/github.com/gopacket/gopacket-1.6.1

dependabot/go_modules/github.com/coreos/go-oidc/v3-3.19.0

dependabot/go_modules/github.com/pires/go-proxyproto-0.12.0

fix/signal-watchdog-sync-stop

docs/agent-network

test/affected-logic

fix/revert-ice-filter

refactor/simplify-affected-peers

pascal-filter-policies-by-direction

claude/lock-contention-peer-connect-g8t6au

dmitri-filter-policies-by-direction

refactor/migrate-profiles-to-go

profile-bindings-ios

fix/skip-restart-unchanged-route

fix/mgmt-cache-async-resolve

refactor/wails-update-105

client_lifetime_serialization_refactor

fix/browser-ssh-2

fix/ipv6-and-netstack-accept-loop

fix/browser-ssh

profile-id-name-test

refactor/mgmt-bootstrap

feat/getting-started-unified-wizard

socket-grpc-permissions

fix/mysql-index-migration

windows-dns-firewall

tests/enable-race-on-tests

ui-refactor-gtk3

feature/affected-peers-grpc

profile-id

lazyconn-first-packet-fix-v2

claude/focused-gates-VMTgb

ui-tray-linux-leftclick

fix/ctx-enrichment

daemon-owner

feature/android-client-ssh

worktree-accept-ra-forwarding

nmap/combined-deploy

task/align_protobuff_toolset

feature/session-extend

add-json-yaml-flags

refactor/ephemeral-cleanup

claude/webtransport-relay-wasm-mUjY9

claude/vnc-udp-feasibility-6KB1U

fix/wgport-config

e2e-windows-dns-combined

fix/login-cmd-root-flags

feat/reseller-openapi-spec

github-issue-resolver

add-steamos-support

fix-darwin-uninstaller

flutter-test

ci/freebsd-pkg-bootstrap

cached-serial-check-on-sync

fix-mgmt-cache-bypass-overlay

revert-easyjson-5938

revert-ice-5820

revert-firewalld-5928

refactor/permissions-manager

revert-dns-5935-systemd-resolved

revert-dns-5935-5945

revert-dns-5945-mgmt-cache

feature/log-most-busy-peers

prototype/ui-wails

coderabbitai/utg/8ae8f20

feature/use-peer-fqdn-on-https

release/0.68.3

add-slack-channel

claude/rdp-token-passthrough-eNcqW

transparent-proxy

fix/macos-stale-route-eexist

crowdsec-selfhosted

fix/remove-otel-units

entire/checkpoints/v1

fix/getting-started

feat/static-connectors-combined-server

feature/use-local-keys-embedded

feature/fleetdm

set-env-only-if-not-fork

feature/expose-has-channel

fix/connection-status-race

fix/filter-cgnat-cni-ice-candidates

feature/check-cert-locker-before-acme

test/proxy-fixes

test/proxy-mtu

prototype/ui-tauri

test/proxy-speed

fix-reused-ports

feat/migrate-to-embedded-idp

feature/add-serial-to-proxy-merged

deploy/proxy-serial

test/connection

feature/disable-legacy-port

feature/flag-to-disable-legacy-port

test/perftest

fix/http-redirect

poc-token-command

dn-reverse-proxy

prototype/reverse-proxy-rename

prototype/reverse-proxy-logs-pagination

feature/client-metrics

prototype/reverse-proxy-clusters

debug-dns-route

fix/win-dns-batch

add-extra-route-logs

job-stream-notify-disconnection-eof

deploy/secrets-manager

trigger-proxy-update

bug/update-ios-client-code-build-tags

sync-client-netmap-serial

log/conn-disconn

nmap/compaction-deploy

ci-win-test

feature/disk-encryption-check

wasm-debug

swap-dns-prio

fix/dex-config

feature/migrate-auto-groups-to-table

nmap/compaction

dex-nocgo-stub

feature/exclude-terraform-from-rate-limiting

test-freebsd

retries-refactor

coderabbitai/docstrings/b7e98ac

feat/integrate-zitadel

bug/ios-hanging-reconection

zitadel-idp

feat/network-map-serial

refactor/get-account-no-users

feat/auto-upgrade

feature/report-high-pat-id

feature/temporary-access-for-resource

fix/nmap-fwrules

dont-restart-dns

prototype/ui

update-gomobile

go-dns-for-ice

wasm-ldflags

test-ldflags

wasmbuild-test

feature/networks-s2s

vk/compare-nmaps

dbg/bothmaps

reorder-dns-shutdown

fix/relay-reconnection-race

fix/nmap-exitnodes

vk/debug/nmap-both

move-licensed-code

feat/better-daemon-connection-lost-message

feat/auto-update-2

test/timings

refactor/getaccount-raw

tests/nmap-getaccount

refactor/nmap

refactor/nmap-limit-buffer

feature/detect-mac-wakeup

feature/extract-modules

quick-setings

feat/sync-limiter

feature/store-cache-impl

fix-install-version

feature/store-metrics

feature/metrics-on-store

feature/use-gorm-cache

loadtest-signal

unsymmetrical-squash

refactor/reducate-signaling

test/update-reduce

feature/store-cache

feature/remote-debug

cli-ws-proxy-backend-addr

feat/mgmt-map-serial

snyk-fix-d9d0081a4c7f9137bdb59d0d50a141a2

snyk-fix-7415cea5a11acd66753540ca2c598c63

job-yml-update

feature/android-allow-selecting-routes

fix/up-sequence

fix/dns-hash-update

snyk-fix-967adae9863f17f108ce8948d9117b8d

log/getaccount-by-peer

signal-suppressor

dns-exit-node

feature/auto-updates

feature/cache-srv-key

merged-fixes

fix/missed-offers-and-debug

debug-and-fixes

poc-wasm-clean-backend-s2s

test/remote-debug

debug-api

fix/remove-gpo-if-empty

fix/test-freebsd

fix/mysql-setup

fix/remove-logout-btn

handle-existing-domain-user

chore/unify-domain-validation

snyk-fix-c5fafc8a50ce1f29046e25a1fc346185

feat/profile-edit-btn

snyk-fix-a54966211e18d4cf67e5a2757cc006d1

log-short-id

feat/logout-ephemeral

log-checks

batch-wg-ops

nb-interface-default

feat/aws-integration

add/race-test

feature/relay-feature-versioning

fix/systemd-service-logs

poc/preprocessed-map

add-account-onboarding

bind-ipv6

fix/merge-main

logs/peerlogs-addpeer

feature/net-297-network-migration

feature/support-skip-auto-apply-exit-node-routes

set-cmd

set-command-with-cursor

feature/limit-update-channel

stop-using-locking-share

feature/poc-lazy-detection

feature/net-248-removal-of-sync-mutex-locks

test/multiple-peer-logging

preresolve

add-ns-punnycode-support

apply-routes-early

windows-search-domains

fix/connecting-route-filter

feature/management/rest-client/impersonate

debug-local-records

resource-fields-snake-case

test/grpc-rate-limit

traffic-correlation-policy

feature/rest-client-options

feat/events-metrics

feature/buf-cli

test/add-ratelimiter

test/remove-write-lock-on-add-peer

fix/add-peer-semaphore

feature/users-roles-endpoint

mlsmaycon-patch-1

debug-user-role

chore/primary-key-on-networks

feature/update-account-peers-buffer-startup

remove-ubuntu2004-runners

refactor/permissions-no-pat-allowed

ref/logrus-factory

use-conntrack-zone

deploy/permissions-account

feature/lazy-connection-idle

ref/improve-test-cov

restore-pr-3440

test/increase-grpc-timeouts

feat/buffer-account-peers-update

test/networkmapgeneration-changes

feature/base-manager

feature/flow-receiver

chore/benchmark-with-large-runner

refactor/handshake-initiator

client/ui-update-systray-icons

userspace-router

wgwatcher-test

output-if-key-already-exists

fix/relay-reconnection

feature/port-forwarding-client-codecleaning

detached2

test/callbacks-nil-iceconninfo

refactor/optimize-peer-expiration

enable-udp-port-for-docker-template

fix/relay-update

feature/apply-posture-netmap

fix/group-update-existing-resource

conntrack-stats

upgrade-okta-sdk

multi-price

test/conn-stat

set-min-parallel-tests-for-management

dns-interceptor

debug-dns

router-dns

add-static-system-info

debug-0.29.4

debug-0.33.0

account-refactoring

relay/2800_quic

route-get-account-refactoring

test/seed-random-routes

feature/get-account-refactoring

test/reconnect-race-condition

refactor/get-account-usage

feature/add-session-id-to-update-channel

improve-ipv4conn

fix/async-pion-event-handling

debug

add-offload

feature/validate-group-association-debug

fix/limit-conn-for-sqlite

test/engine-iface

test/transaction-for-jwt-sync

fix/engine-stop-in-foreground

feature/add-mysql-support

test-migration

refactor/header-size-values

relay/eliminate-gob

test/signal-dispatcher-with-relay

relay/debug

validate-icon

feature/ipv6-support

use-pre-expanded-peers-map

feature/use-signal-dispatcher

validate/peer-status

add-read-write-times

fix/sync-peer-race

feature/relay-status

netmap

evaluate/network-map-hash

fix/lower-dns-resolve-interval-on-fail

feature/relay

fix/go-mod-version

upgrade-nftables

synology-userspace-mode

fix/use-ip-for-default-routes-on-darwin

fix/proxy_close

enable-release-workflow-on-pr

deploy/peer-performance

feature/permanent-turn

feature/permanent-turn-proxy

deploy/posture-check-sqlite

feature/optimize_sqlite_save

debug-ios-behavior

fix/delete-route-only-after-adding

tshoot/windows-logger

remove-new-routing

refactor/eliminate-repo-dependency

add-arm-to-ci

refactor-demo-account-object

test/abc2

test/abc

send-ssh-rosenpass-config-meta

refactor-demo

ensure-schedule-never-runs-non-positive

feature/peer-validator-groupmgm

feature/peer-validator-fix

fix/include-active-dashboard-users

fix/handle-canceling-schedule

fix/geo-download

debug-google-workspace

yury/resolve-ip-to-location

feature/extend-sysinfo

sqlite-async-peer-status

yury/add-postgresql-store

fix/route

test-build

posture-checks-poc

debug-keycloak-idp

poc/netstack

for-pascal-tmp

peer-logout-management

manual-peer-logout

detached

chore/refactor-management

test/dns-bind

fix/enforce-acl-for-containers

yury/use-sync-map-in-updatechannel

fix/events-key-handling

filter-cache-on-load-account

fix/user-expiration

handle-user-context-cancellation

nb-client-k8s-statefulset

fake-addr

fix/iptables_in_docker

ebpf-debug

update-getting-started-flow-use-postgres

fix/peer_list_notification

feature/device-authentication-with-client-secret

feature/keep_alive

feat-groups-from-jwt

separate_proxy_from_wgconfig

fix/wg_conn

wg_conn_fix

wg_bind_parallel_processing

fix-rollback-get-acls

proxy_cfg_cleanup

performance-improvement-rego

update-lock-log-level

feat-client-side-acl

refactor/move_grpcserver_logic_to_account_manager

feature/event-storage

feature/update-idp-redeeming-invite

feature/api-peer-info

return-groupminimum-setupkey

feature/interface-bind

documentation_enhancement

fix-peer-registration

ssh

users_cache

pass-client-caller

client_caller_type

revert-283-feat-fix-windows-installer

periodic-peer-updates

ebpf

braginini/wasm

1 Participants

Notifications

Due Date

No due date set.

Dependencies

No dependencies set.

Reference: DYNR/netbird#8608