From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aj Mirani Subject: Re: Why is this not working??? Date: Wed, 26 Apr 2006 08:57:26 -0400 Message-ID: <20060426125726.GI5568@orbitor.ops.internal.tucows.com> References: <200604251615.03991.stratism@gmail.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <200604251615.03991.stratism@gmail.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: netfilter-bounces@lists.netfilter.org Errors-To: netfilter-bounces@lists.netfilter.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Stratos Margaritis Cc: netfilter@lists.netfilter.org Why not put something like this into your INPUT chain: -A INPUT -p tcp -m tcp --dport 22 -s xxx.xxx.xxx.xxx/28 -d yyy.yyy.yyy.yyy -j ACCEPT Also for your line: -A INPUT -p tcp --syn -m limit --limit 5/s -i eth0 -j ACCEPT This is a server wide limit not a per host limit which depending on what you're trying to prevent may not be the best way to do it. If you are trying to prevent a syn attack but still want the server to respond to legitimate requests try something like this: -A INPUT -p tcp -m tcp --tcp-flags SYN,RST,ACK SYN -m recent --set --name SYNATTACK --rsource -A INPUT -p tcp -m tcp --tcp-flags SYN,RST,ACK SYN -m recent --update --seconds 20 --hitcount 10 --name SYNATTACK --rsource -j DROP -A INPUT -p tcp -m tcp --tcp-flags SYN,RST,ACK SYN -j ACCEPT This dynamically put hosts on a 'blacklist' who are trying to connect too fast (more that 10 times in a 20 second period.) with the use of --update it will keep them blacklisted as long as they continue to send packets too fast. On Tue, Apr 25, 2006 at 04:14:59PM +0300, Stratos Margaritis wrote: > Can someone help me find out why is this rule does not work? > > *filter > :INPUT DROP [1803:271102] > :FORWARD DROP [0:0] > :OUTPUT DROP [0:0] > -A INPUT -i lo -j ACCEPT > -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT > -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT > -A INPUT -p tcp -m tcp --dport 25 -j ACCEPT > -A INPUT -p tcp -m tcp --dport 53 -j ACCEPT > -A INPUT -p udp -m udp --dport 53 -j ACCEPT > -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT > -A INPUT -p icmp -j ACCEPT > -A INPUT -p tcp -j REJECT --reject-with tcp-reset > -A INPUT -p tcp --syn -m limit --limit 5/s -i eth0 -j ACCEPT > -A FORWARD -p tcp -i eth0 -s xxx.xxx.xxx.xxx/28 -o eth1 -d yyy.yyy.yyy.yyy -j > ACCEPT > -A FORWARD -j LOG > > Where xxx.xxx.xxx.xxx is a real network that should be allowed to contact the > server yyy.yyy.yyy.yyy both of which are having real IP's. > > > -- > Stratos > stratism@gmail.com -- Aj Mirani Network Operations Tucows.com Inc