CURRENT: ipfw: problems with timeouts and worse network performance

Jan Bramkamp crest at
Fri May 20 13:28:45 UTC 2016

On 20/05/16 14:54, Vladimir Zakharov wrote:
> Hello
> On Fri, May 20, 2016, O. Hartmann wrote:
>> I reported earlier about broken pipes in ssh sessions to remote hosts,
>> which occur on an erratic basis. i'm investigating this problem now and
>> it seems that it is also ipfw-related, but I'm not sure. This problem
>> is present since a couple of weeks now.
> Maybe this could help...
> I've also experienced problems with broken pipes in ssh sessions some
> time ago. Setting in sysctl.conf
> net.inet.ip.fw.dyn_ack_lifetime=3600
> fixed problem for me. I didn't experiment with the value though. So,
> possibly, changing default value (300s) to 1 hour is overkill :).

By default the OpenSSH SSH client is configured to use TCP keepalives. 
Those should produce enough packets at a short enough interval to keep 
the dynamic IPFW state established.

Does your traffic pass through libalias?

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