Long keepidle time

[Simon Walton]

Mike Silbersack wrote:
> 
> On Fri, 11 Aug 2006, Simon Walton wrote:
> 
>>  Is there any reason why the default initial timeout for keep alive
>> packets needs to be as long as two hours? This period causes the 
>> dynamic rules in my firewall filter to timeout.
>>
>>  Is there a major objection to reducing the default idle time to
>> say 3 to 5 minutes?
>>
>> Simon Walton
> 
> 
> On reason behind a 2 hour keepalive is so that you don't have a 2 minute 
> network outage that causes all your connections to timeout.
> 
> Of course, as you point out, in the modern age of firewalls, more 
> frequent keepalives can be a good thing.
> 
> I don't forsee us changing FreeBSD's default keepalive setting, but 
> you're more than welcome to change the setting on your own system.
> 
> Also note that ipfw2 sends keepalive packets on its own, maybe you could 
> switch to it and/or add that functionality to your favorite firewall 
> package. :)

   Thanks. I did not go with ipfw2 partly because of concerns about
whether it was stable enough (this is on 4.10) and also because
it requires rebuilding part of userland. Perhaps this would
be the way to go after all.

   Note that the probes are retransmitted a few times (I think eight times)
before the connection is considered dead, so it would take longer
than two minutes.

Simon Walton