Re: [RFC] Per-conntrack timeout target

[Patrick McHardy <kaber@trash.net>]

Phil Oester wrote:
> I use a fairly short 2 hour established timeout on firewalls I operate,
> which works fine for most purposes.  Occasionally, however, it would
> be nice to have a longer timeout for *certain* types of traffic
> such as SSH or telnet sessions.  
> 
> So, below find a TIMEOUT target to enable such per-conntrack timeouts.
> Syntax for SSH would be something like:
> 
>         iptables -A foo -p tcp --dport 22 -j TIMEOUT --timeout 123456
>         iptables -A foo -p tcp --dport 22 -j ACCEPT
> 
> It could of course also be used to lower the timeouts on some traffic,
> such as HTTP.
> 
> Please review, comment, criticize, etc.  Note that at present it only
> handles TCP/UDP traffic.  If deemed "merge-worthy", support for other
> protos will be added.


The only downside I see is that it adds another 4 bytes to the conntrack
structure and distributions are probably going to enable it, like
everything else. It would be nice if we could put this in a ct_extend
structure, but that would mean you're only able to set it for new
connections. What do you think about this?