Posted: Wed Apr 30, 2025 12:52 Post subject: I may have discovered a bug where QoS breaks port forwards
Don’t have the time tonight to chase this, but if maybe someone could let me know what logs I would need to prove this. Or maybe someone can recreate the bug.
When QoS is setup with HTB FQ_CODEL and downlink are set without a limit i.e with a 0 value with a limit on uploads, doesn’t seem to matter what is set my port forwards no longer work. SYN FIN RST flags also enabled.
When set this way, none of my forwarded ports are externally accessible. Once I do set a downlink limit the forwards work again.
This could be intended, I don’t exactly understand the routing here. But it would be odd to me if this isn’t possible.
Look forward to coming back to this thread in the morning.
This behaviour is consistent over many builds over the last few weeks. Resets in between. Currently on r60791.
Okay so it is a gremlin - I've now tested and reproduced the issue on a fresh install without any other settings changed excluding a port forward. Port forwards fall over when you set an uplink limit but not a downlink limit, yet strangely, not vice versa.
Not exactly sure where to start and what would be useful to diagnose this. iptables? syslog logs? strace and tcpdump?
