Re: Use netfilter to block DoS

[Dan Egli <dan@xxxxxxxxxxxxxxxxxxxxxxx>]

Peter Bi wrote:

> Hi,
>
> I have two questions related to Denial of Service:
>
> 1) If I want to set up a syn-flood protection, based on 1 per second (bursts
> 5), should I use
>
> iptables -A INPUT -p tcp --syn -m limit --limit 1/s -j DROP
> or
> iptables -A INPUT -p tcp --syn -m limit --limit 1/s -j ACCEPT
>
> The first one seems to drop those which EXCEED 1 per second
>  
I have a similiar rule, and I use ACCEPT.  I have my system configured 
to allow up to 5 ICMP messages per second. Beyond that they are dropped.
iptables -A INPUT -p icmp -m limit --limit 5/sec -j ACCEPT