Add Service - This is a drop down list of preset names and relevant common port numbers. They can be customized to suit your own purposes or new services can be entered if required. The port mapper service allows you to bring a remote service on an internet based machine to appear to be running on the local computer this is especially used for smtp, POP3, DNS, IRC and Instant messengers. It supports both TCP and UDP protocols and provides end to end tunneling with no service interruption. This is not affected by the content control system, banned urls or allowed urls as these are http protocol specific. You can create additional port forwarding for other applications by selecting CUSTOM .