I use outpost as my firewall while going through it's configuration i found that in list of port trusted the UDP section contained the UDP port 31337 was selected as the trusted port.
While i see no way to add or remove listed port's. I really find it very confusing that a firewall like Outpost has such a port listed as trusted and also has not given a way to remove that port.
Any other user with Outpost 2.5 Pro please go through your configuraion
anyway I have attached the JPEG image.