You can stealth it by adding
DROP net fw tcp 93
to the bottom of /etc/shorewall/rules, just above "#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE"
Then either
Reboot or start the PCC, click on System -> Enable or disable system services; find the Shorewall service, click Stop and when it stops click Start.
No need for rebooting, just restart the service itself.
Open a console window as the root user and use the following command
service iptables restart.
That rebooting stuff is oh so Windows like .........