freebsd stable - Feb 2021 - 13.0-BETA1: ipfw regression?

I'm having issues with stale TCP connections after the upgrade from 12.2 to
13.0-BETA1.

Symptoms:
Outgoing TCP connections no longer receive data after being idle.

I can do more testing later, but I think these ipfw rules trigger the problem:
- check-state
- allow tcp from me to any setup keep-state
- deny ip from any to any

After establishing an outgoing connection (e.g, via netcat), I see a new
dynamic rule and the 300s counter running down via
# ipfw -Da list

net.inet.ip.fw.dyn_keepalive is set to 1, so the timer should be refreshed via
keep-alive on idle connections.

Don't know if it's deterministic, but from what I've seen so far:
- When counter gets low the first time, it is reset to 300 as expected.
- When the counter nears zero for the second time, the dynamic rule is deleted
and I get ipfw denies.

On Tuesday, February 9, 2021 11:23:32 PM CET Stefan Ehmann
wrote:
> I'm having issues with stale TCP connections after the upgrade from
12.2 to
> 13.0-BETA1.
>
> Symptoms:
> Outgoing TCP connections no longer receive data after being idle.
>
> I can do more testing later, but I think these ipfw rules trigger the
> problem: - check-state
> - allow tcp from me to any setup keep-state
> - deny ip from any to any
PR created:
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=253476