Hi,
Thanks. If you bear with a couple "hopefully-not-too-naive" questions ...
I seems to me that you are saying the actions you wish to stop are from "s <offending_ip>" using "-p tcp" ... why the need to specify the destination of "-d <my_ip>" (since if this iptables rule is called, it must have reached me regardless of my_ip) and "--dport 80" (would there be any destination port that I would allow such action from this offending_ip to occur on?).
Yes, that's correct. You don't need to include the destination if you only have one IP address on that host.
I am seeing in the default F14 iptables:
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
This looks to me like tcp on dport 22 is allowed and there I would think that the minimal change would be to insert a rule before this which says "anything from offending_ip via tcp should be rejected".
I'm still trying to get comfortable with iptables and, even though there is alot of stuff out there, I'm still working to get the necessary critical mass of understanding so it all falls into place. This thread looked like a good chance to see if I'm closer to understanding.
Yes, that's a good approach too. If you are editing the existing iptables config script from /etc/sysconfig/iptables, then that's exactly what you would do. Something like this should work:
# Firewall configuration written by system-config-firewall # Manual customization of this file is not recommended. *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT -A INPUT -p icmp -j ACCEPT -A INPUT -i lo -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j DROP -s <offending_ip/range> -A INPUT -m state --state NEW -m tcp -p tcp --dport 25 -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 443 -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
the "<offending_ip/range>" might be something like 1.2.3.0/24 to block the entire 256 addresses on that network.
HTH, Alex