[ale] iptables limits?

[Jim Popovitch]

On Thu, 2005-06-02 at 19:01 -0400, James P. Kinney III wrote:
> On Thu, 2005-06-02 at 17:04 -0400, Jim Popovitch wrote:
> > Are there any known limits to the number of rules in iptables?  I
> > currently have about 27000+ rules, with no noticeable issues.  What's
> > the upper limit, if there is any, and what are the limiting factors?
> 
> 27000+ !!
> 
> You need to get out more and see the big blue room :)

Let me be a bit clearer... I use a 50+ line script to generate those
rules.  No way that I am going to write 27000+ lines of 90% the same
thing.  ;-)


> Ram is the only limit I have seen in the kernel specs on it. For most
> modern systems that are mostly dedicated to firewalling, the wire speed
> will always be the limiting factor. The iptables process (barring
> strange loops that are VERY BAD) is a quite streamlined, multi-threaded
> process. I do know that performance can suffer if rule ordering is poor
> and every packet is forced through every table. I get pretty good
> results with a table for each protocol/port that is allowed that nees
> further filtering to block out bozo's (morons doing ssh scans should get
> blocked on all ports as they are up to no good)

Thanks,

-Jim P.