On our Internet connected servers, besides using iptables to limit incoming connections, we are using TCP wrappers (hosts.allow and hosts.deny) to reject connections originating on untrusted networks.
Probably you’re already using iptables to block incoming traffic on port 22 (ssh), which is fine but what we want to do is increase security by using a more persistent method for blocking traffic. Don’t get me wrong, iptables’ rules can (and should) be made persistent but sometimes while trying new rules some key ports can be left open. Continue reading »