[PR #5300] [CLOSED] [client] Fix port reuse in tcp conntrack #27639

New Issue

saavagebueno · 2026-08-05T07:09:00-04:00

saavagebueno commented

2026-08-05 07:09:00 -04:00

📋 Pull Request Information

Original PR: https://github.com/netbirdio/netbird/pull/5300
Author: @lixmal
Created: 2/12/2026
Status: ❌ Closed

Base: main ← Head: fix-reused-ports

📝 Commits (3)

09f538e Treated tombstoned conns as new
6df3b6d Handle TCP port reuse for TIME-WAIT connections
e671e2d Merge branch 'main' into fix-reused-ports

📄 Description

Describe your changes

Issue ticket number and link

In the userspace filter TCP conntrack, if a port was reused, it extended a connection's lifetime whereas it should treat this as a new connection (for SYN).

Also adds a NB_USPFILTER_LOG_BUFFER env var to increase the uspfilter log buffer

Stack

Checklist

Is it a bug fix
Is a typo/documentation fix
Is a feature enhancement
It is a refactor
Created tests that fail without the change (if possible)

By submitting this pull request, you confirm that you have read and agree to the terms of the Contributor License Agreement.

Documentation

Select exactly one:

I added/updated documentation for this change
Documentation is not needed for this change (explain why)

Docs PR URL (required if "docs added" is checked)

Paste the PR link from https://github.com/netbirdio/docs here:

https://github.com/netbirdio/docs/pull/__

Summary by CodeRabbit

Bug Fixes
- Improved connection tracking so closed or TIME-WAITed connections are correctly treated as superseded, enabling reliable port reuse and preventing stale entries from blocking new connections.
Tests
- Added extensive tests covering port reuse, tombstone/TIME-WAIT scenarios, retransmits, and edge-case packet timing.
Chores
- Made log buffer size configurable via an environment variable.

_{🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.}

## 📋 Pull Request Information **Original PR:** https://github.com/netbirdio/netbird/pull/5300 **Author:** [@lixmal](https://github.com/lixmal) **Created:** 2/12/2026 **Status:** ❌ Closed **Base:** `main` ← **Head:** `fix-reused-ports` --- ### 📝 Commits (3) - [`09f538e`](https://github.com/netbirdio/netbird/commit/09f538eb308c4ad71b6b6a8d30158ad5132db09f) Treated tombstoned conns as new - [`6df3b6d`](https://github.com/netbirdio/netbird/commit/6df3b6de54fb00505b87fe4c0eac0d25dacef098) Handle TCP port reuse for TIME-WAIT connections - [`e671e2d`](https://github.com/netbirdio/netbird/commit/e671e2daeb1ecc9ebc2cd89624a2445ea0e18fee) Merge branch 'main' into fix-reused-ports ### 📄 Description ## Describe your changes ## Issue ticket number and link In the userspace filter TCP conntrack, if a port was reused, it extended a connection's lifetime whereas it should treat this as a new connection (for `SYN`). Also adds a `NB_USPFILTER_LOG_BUFFER` env var to increase the uspfilter log buffer ## Stack  ### Checklist - [x] Is it a bug fix - [ ] Is a typo/documentation fix - [ ] Is a feature enhancement - [ ] It is a refactor - [x] Created tests that fail without the change (if possible) > By submitting this pull request, you confirm that you have read and agree to the terms of the [Contributor License Agreement](https://github.com/netbirdio/netbird/blob/main/CONTRIBUTOR_LICENSE_AGREEMENT.md). ## Documentation Select exactly one: - [ ] I added/updated documentation for this change - [x] Documentation is **not needed** for this change (explain why) ### Docs PR URL (required if "docs added" is checked) Paste the PR link from https://github.com/netbirdio/docs here: https://github.com/netbirdio/docs/pull/__  ## Summary by CodeRabbit ## Summary by CodeRabbit * **Bug Fixes** * Improved connection tracking so closed or TIME-WAITed connections are correctly treated as superseded, enabling reliable port reuse and preventing stale entries from blocking new connections. * **Tests** * Added extensive tests covering port reuse, tombstone/TIME-WAIT scenarios, retransmits, and edge-case packet timing. * **Chores** * Made log buffer size configurable via an environment variable.  --- <sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>

saavagebueno added the pull-request label 2026-08-05 07:09:00 -04:00

saavagebueno closed this issue

2026-08-05 07:09:00 -04:00

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Reference: DYNR/netbird#27639