631 IPP (Internet Printing Protocol) - System Port

631 is a System Port. Transport Protocol TCP UDP , 631 Service Name ipp, Service Name Description: IPP (Internet Printing Protocol).

Port	Protocol	Service Name	Description	Source
631	TCP UDP	ipp	IPP (Internet Printing Protocol)	IANA
631	TCP UDP		Internet Printing Protocol (IPP),Official	wikipedia
631	TCP UDP		Common Unix Printing System (CUPS),Unofficial	wikipedia
631	TCP UDP		Mac OS X RPC-based services, Used by NetInfo, for example	Apple.com
631	TCP		Internet Printing Protocol (IPP), Mac OS X Printer Sharing, Printing to many common printers	Apple.com
631	TCP UDP	ipp	IPP (Internet Printing Protocol)	bekkoame

Port	Service Name	Description
2016	bootserver
3531	joltid	Joltid
3532	raven-rmp	Raven Remote Management Control
4259	vrml-multi-use	VRML Multi User Systems
5053	rlm	RLM License Server
5284		Unassigned
5978		Unassigned
5995		Unassigned
6062	x11	X Window System
7188		Unassigned

A port is an endpoint of communication in an operating system. While the term is also used for hardware devices, in software it is a logical construct that identifies a specific process or a type of service.

Port numbers are assigned in various ways, based on three ranges: System Ports (0-1023), User Ports (1024-49151), and the Dynamic and/or Private Ports (49152-65535);

The Well Known Ports are assigned by the IANA and on most systems can only be used by system (or root) processes or by programs executed by privileged users. Ports are used in the TCP [RFC793] to name the ends of logical connections which carry long term conversations. For the purpose of providing services to unknown callers, a service contact port is defined. This list specifies the port used by the server process as its contact port. The contact port is sometimes called the "well-known port". To the extent possible, these same port assignments are used with the UDP [RFC768]. The range for well-known ports managed by the IANA is 0-1023.
DYNAMIC AND/OR PRIVATE PORTS Registered Ports are those from 1024 through 49151.
The Dynamic and/or Private Ports are those from 49152 through 65535