Version 0.5 of BlockSSHD
is out with a bug fix.
"BlockSSHD protects computers from SSH brute force attacks by dynamically
blocking IP addresses by adding iptables rules."
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BlockSSHD version 0.5 released (SourceForge)
Posted Jul 20, 2006 10:00 UTC (Thu) by nix (subscriber, #2304)
[Link]
Alternatively you could protect them from SSH brute force attacks by allowing only challenge-response authentication and disabling password authentication on machines exposed to the Internet.
Automatically updating iptables like this is tantamount to handing attackers a way to get your system to block anything they like, on command. Helpful for DoS attacks...
BlockSSHD version 0.5 released (SourceForge)
Posted Jul 20, 2006 14:50 UTC (Thu) by fm2503 (guest, #2776)
[Link]
Still it can get annoying even if you don't have password authentication turned on. iptables can do this quite neatly without the need to monitor logfiles. I use:
#!/bin/sh
iptables -A INPUT -m tcp -p tcp --dport 22 -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -m tcp -p tcp -s My.local.Lan.0/24 --dport 22 -j ACCEPT
iptables -A INPUT -m tcp -p tcp -s Trusted.Internet.Machine --dport 22 -j ACCEPT
iptables -A INPUT -m tcp -p tcp --dport 22 -m state --state NEW -m limit --limit 3/min --limit-burst 3 -j ACCEPT
iptables -A INPUT -m tcp -p tcp --dport 22 -j LOG --log-prefix SSHBRUTE
iptables -A INPUT -m tcp -p tcp --dport 22 -j DROP
DenyHosts
Posted Jul 20, 2006 18:41 UTC (Thu) by pcharlan (guest, #29128)
[Link]
I haven't used BlockSSHD, but we have deployed DenyHosts on a few machines and it appears to work well. It's a python script that adds to /etc/hosts.deny when it notices N unsuccessful attempts to log into your machine.