Commands to edit iptables

To view the current rules and also view the rule ID use the following:

iptables -L -n –line-numbers
                     or
iptables -nL -v –line-numbers

To delete a rule use:

iptables -D INPUT X  (where x is the ID of the rule in question)

To insert a rule before another use the following:

iptables -I INPUT X -s 192.168.2.0/24 -j DROP (where X is the rule above which the rule is to be inserted)

To replace a rule:
iptables -R INPUT X -s 192.168.3.0/24 -j DROP

Make sure to save as changes will be dropped on reboot

iptables-save > /etc/iptables.rules
or
/sbin/service iptables save