Iptables

Show Rules

With line numbers and don't resolve IP's:

 iptables -nL --line-numbers

Delete a line

e.g., line #35:

 iptables -D INPUT 35

Append Rule

Adds the rule to the END of the list.

Allow single port from a network:

 iptables -A INPUT -s [src-ip/sm] -p tcp -m tcp --dport [dest-port] -m conntrack --ctstate NEW -m comment --comment "[comment]" -j ACCEPT

Allow multi ports from a network:

 iptables -A INPUT -s [src-ip/sm] -p tcp -m multiport --dports [dest-port1],[dest-port2] -m conntrack --ctstate NEW -m comment --comment "[comment]" -j ACCEPT

Insert Rule

Inserts a rule before a specific line number:

 iptables -I INPUT [line#] -s [src-ip/sm] -p tcp -m tcp --dport [dest-port] -m conntrack --ctstate NEW -m comment --comment "[comment]" -j ACCEPT

Save iptables

Make changes persistent - otherwise you'll lose them at next reboot:

 iptables-save > /etc/sysconfig/iptables