Iptables Chain Example

Helps making firewall instructions shorter by chaining commonly used rules together with -j.

Create chain 'Maildrop' and chain it with existing DROP chain:

# iptables -N Maildrop
# iptables -A Maildrop -j LOG --log-prefix 'DENIED MAIL CHECK' --log-level 4
# iptables -A Maildrop -j DROP

Chain input rules to 'Maildrop', they will get prefix-logged and dropped:

# iptables -A INPUT -p tcp -i eth0 --dport 110 -j Maildrop
# iptables -A INPUT -p tcp -i eth0 --dport 995 -j Maildrop
# iptables -A INPUT -p tcp -i eth0 --dport 143 -j Maildrop
# iptables -A INPUT -p tcp -i eth0 --dport 993 -j Maildrop