User Ports are assigned by IANA using the "IETF Review" process, the "IESG . tacacs 49 tcp Login Host Protocol (TACACS) [Pieter_Ditmars] [Pieter_Ditmars] tacacs . gppitnp 103 tcp Genesis Point-to-Point Trans Net gppitnp 103 udp Genesis [Susie_Snitzer] [Susie_Snitzer] imap 143 tcp Internet Message Access [IESG] .