Ports. The Art of Web ~ System: fail2ban and iptables. Around the beginning of 2005 we saw an increase in brute-force ssh attacks - people or robots trying different combinations of username and password to log into remote servers.
A quick search on this topic returns many references to iptables and ipchains but noone really explained how they work. Having just gone through this learning curve myself, and found a satisfactory solution in the fail2ban package, I'm going to try and explain how to achieve the simple goal of banning IP addresses that make repeated failed ssh login attempts. Open Source Network Gateway. Main Page - Fail2ban.