iptables

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IPTABLES

Statefull and Powerfull Firewall.

Enable for SSH Bruteforce Prevention

This is not a 100% proof setup as it does not block based on the result of authentication.
It just work based on connection.

Simple Rules

iptables -N BRTBLK
iptables -A INPUT -p tcp --dport 22 -m state –state NEW -j BRTBLK
iptables -A BRTBLK -m recent –set –name SSH
iptables -A BRTBLK -m recent –update –seconds 45 –hitcount 5 –name SSH -j DROP

Rules With Exceptions

Replace <Exception> with your IP.
You can use multiple rules with diff. IP to allow exceptions.

iptables -N BRTBLK
iptables -A INPUT -p tcp –dport 22 -s <Exception> -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -m state –state NEW -j BRTBLK
iptables -A BRTBLK -m recent –set –name SSH
iptables -A BRTBLK -m recent –update –seconds 45 –hitcount 5 –name SSH -j DROP

Rules to Log Bloked IP

iptables -N BRTBLK
iptables -A INPUT -p tcp --dport 22 -m state --state NEW -j BRTBLK
iptables -A BRTBLK -m recent --set --name SSH
iptables -A BRTBLK -m recent --update --seconds 45 --hitcount 5 --name SSH -j LOG --log-level info --log-prefix "Bad IP : "
iptables -A BRTBLK -m recent --update --seconds 45 --hitcount 5 --name SSH -j DROP

iptables.1265320325.txt.gz · Last modified: 2020/08/10 02:30 (external edit)