Ubuntu 9.04: Why is IPP(TCP 631) open and how do I disable it?

CUPS, which is part of the Linux Standard Base, is enabled. To stop the service:

sudo /etc/init.d/cupsys stop 

To disable it from startup:

update-rc.d -f cupsys remove
update-rc.d cupsys stop 20 2 3 4 5 .

Another way to stop this print server is to open a terminal shell ctrl + alt + t and type sudo service cups stop

This will stop the server and close the port, but it will restart on a reboot. You could also restart or start the service this way simply substituting restart or start where stop is in the command. :D

Don't disable it, this is your printer!

To enable it again you can add port TCP 631 to your Firewall. Just type 631 in the Firewall.

More info at the Ubuntu Forums:

Thank you ! I have just deleted the port 631/tcp from FIREWALL because Facebook disconnected me alone wich gave me suspicions. So this was my printer !!! So just I'll just add again ALLOW IN TCP 631 inside my FIREWALL.