[CentOS] Optimizing CentOS for gigabit firewall

Timo Schoeler timo.schoeler at riscworks.net
Mon Dec 21 09:17:48 UTC 2009

thus Pasi Kärkkäinen spake:
> On Fri, Dec 18, 2009 at 09:36:57PM +0200, sadas sadas wrote:
>>    I will explain more deeply. I need to deploy a firewall(s) in front of web
>>    server farm because I need to do billing - I will use CentOS with iptables
>>    + ipset to store a list if my clients so when client doesn't pay his
>>    server's IP is out of the list and he can't access the web server.
>>    Second - I know that iptables is very heavy and it's not recommended to
>>    use it in gigabit firewall but I don't have a choice as far as I know only
>>    ipset works with iptables. I don't know can pf store 500 IPs in one list.
>>    Ipset is written for that purpose.
>>    I can't find information is there linux or BSD distribution with effective
>>    firewall that uses optimized algorithm to store hundreds of IPs and to
>>    forward huge traffic. Any idea?
> I've been using Linux (CentOS5) on gigabit firewalls, for thousands of
> users. No problems.

Yeah, but what is your ruleset?

> Just make sure ip_conntrack_max is big enough, so you don't run out of
> connections. 

Just three months ago I saw a CentOS L2TP cluster explode because of 
this -- and the machines have _plenty_ of RAM each. Turned off 
ip[6]tables entirely and let the Ciscos do this was the only solution.

> There are other things to tune to optimize the performance, but it's
> certainly doable with linux+iptables.

Nail, hammer, etc. ;)

> -- Pasi


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