[PR #6802] [client] Preserve firewall authorization in connection marks #29917

New Issue

saavagebueno · 2026-08-05T08:09:24-04:00

saavagebueno commented

2026-08-05 08:09:24 -04:00

Original Pull Request: https://github.com/netbirdio/netbird/pull/6802

State: open
Merged: No

Describe your changes

Persist NetBird firewall authorization and routed-network marks in conntrack instead of relying on mutable per-packet marks. The DNAT guard now checks connection marks, so kube-router, kube-proxy, and other netfilter consumers can modify packet marks without causing authorized traffic to be dropped.

Both iptables and nftables backends are updated. Routed marks remain classified correctly by netflow.

Issue ticket number and link

Fixes #6022

Stack

This PR is independent

Checklist

I have performed a self-review of my own code
I have tested the changes locally
I have added or updated tests where applicable
I have checked for breaking changes

Documentation

Documentation is not needed

Validation

Cross-compiled Linux test binaries for ./client/firewall/iptables
Cross-compiled Linux test binaries for ./client/firewall/nftables
Cross-compiled Linux test binaries for ./client/internal/netflow/conntrack
git diff --check

Runtime netfilter tests require a Linux environment.

^{Need help on this PR? Tag /codesmith with what you need. Autofix is disabled.}

Summary by CodeRabbit

Bug Fixes
- Improved firewall rule behavior for redirected, masqueraded, and return traffic by switching NAT/ACL handling to use connection (conntrack) marks consistently.
- Strengthened DNAT guard logic to drop incorrectly marked redirected traffic.
- Improved NetFlow direction detection for firewall-managed connections based on these connection marks.
Tests
- Added/updated Linux-focused tests to verify connection-mark-based rule generation and NAT matching/cleanup behavior.

**Original Pull Request:** https://github.com/netbirdio/netbird/pull/6802 **State:** open **Merged:** No --- ## Describe your changes Persist NetBird firewall authorization and routed-network marks in conntrack instead of relying on mutable per-packet marks. The DNAT guard now checks connection marks, so kube-router, kube-proxy, and other netfilter consumers can modify packet marks without causing authorized traffic to be dropped. Both iptables and nftables backends are updated. Routed marks remain classified correctly by netflow. ## Issue ticket number and link Fixes #6022 ## Stack - [x] This PR is independent ## Checklist - [x] I have performed a self-review of my own code - [x] I have tested the changes locally - [x] I have added or updated tests where applicable - [x] I have checked for breaking changes ## Documentation - [x] Documentation is **not needed** ## Validation - Cross-compiled Linux test binaries for `./client/firewall/iptables` - Cross-compiled Linux test binaries for `./client/firewall/nftables` - Cross-compiled Linux test binaries for `./client/internal/netflow/conntrack` - `git diff --check` Runtime netfilter tests require a Linux environment.  --- <a href="https://app.blacksmith.sh/netbirdio/codesmith/netbird/pr/6802"><picture><source media="(prefers-color-scheme: dark)" srcset="https://pr-comments-assets.blacksmith.sh/codesmith/view-with-codesmith-dark-v2.svg"><source media="(prefers-color-scheme: light)" srcset="https://pr-comments-assets.blacksmith.sh/codesmith/view-with-codesmith-light-v2.svg"><img alt="View with Codesmith" src="https://pr-comments-assets.blacksmith.sh/codesmith/view-with-codesmith-dark-v2.svg"></picture></a> <a href="https://backend.blacksmith.sh/track/enable-autofix?expires=1786808434&installation_id=146802194&pr_number=6802&repository=netbirdio%2Fnetbird&return_to=https%3A%2F%2Fgithub.com%2Fnetbirdio%2Fnetbird%2Fpull%2F6802&signature=9712e419e1e17cb5d6a34ad77c961ff3629293f35137fc42a143fa54931b1fa6"><picture><source media="(prefers-color-scheme: dark)" srcset="https://pr-comments-assets.blacksmith.sh/codesmith/autofix-with-codesmith-dark.svg"><source media="(prefers-color-scheme: light)" srcset="https://pr-comments-assets.blacksmith.sh/codesmith/autofix-with-codesmith-light.svg"><img alt="Autofix with Codesmith" src="https://pr-comments-assets.blacksmith.sh/codesmith/autofix-with-codesmith-dark.svg"></picture></a> <sup>Need help on this PR? Tag <code>/codesmith</code> with what you need. Autofix is disabled.</sup>    ## Summary by CodeRabbit * **Bug Fixes** * Improved firewall rule behavior for redirected, masqueraded, and return traffic by switching NAT/ACL handling to use connection (conntrack) marks consistently. * Strengthened DNAT guard logic to drop incorrectly marked redirected traffic. * Improved NetFlow direction detection for firewall-managed connections based on these connection marks. * **Tests** * Added/updated Linux-focused tests to verify connection-mark-based rule generation and NAT matching/cleanup behavior.

saavagebueno added the pull-request label 2026-08-05 08:09:24 -04:00

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Reference: DYNR/netbird#29917