What’s That In My #2 Port?
Normally, a vendor goes to IANA to get a port assigned to them for their service to run on. Each service has a unique port. E.g. - telnet is 23, http is 80.
RFC1700 used to keep this list, but is now out-dated.
See http://www.iana.org/numbers.html for the most up-to-date list.