1. Modify the /etc/shorewall/rules file as needed
2. At the command prompt enter to verify there are no problems:
#] shorewall -v check
3. At the command prompt enter to load the rule:
#] service shorewall restart

Make sure too that shorewall is setup to run on startup using the command:
#] chkconfig shorewall -list

Which should give you the output like:

]# chkconfig shorewall -list
shorewall       0:off   1:off   2:on    3:on    4:on    5:on    6:off

showing the shorewall will run on boot for run levels 2, 3, 4 and 5.

Provided by Chris Stone of Axis Internet