56 XNS Authentication - System Port | Service Name:xns-auth

56 is a System Port. Transport Protocol TCP UDP , 56 Service Name xns-auth, Service Name Description: XNS Authentication.

Port	Protocol	Service Name	Description	Source
56	TCP UDP	xns-auth	XNS Authentication	IANA
56	TCP UDP		XNS (Xerox Network Systems) Authentication,Official	wikipedia
56	TCP UDP		Route Access Protocol (RAP),Unofficial	wikipedia
56	TCP UDP	xns-auth	XNS Authentication	bekkoame

Port	Service Name	Description
744	flexlm	Flexible License Manager
800	mdbs-daemon	IANA assigned this well-formed service name as a replacement for "mdbs_daemon".
962		Unassigned
984		Unassigned
1766	cft-5	cft-5
2201	ats	Advanced Training System Program
3083	tl1-telnet	TL1-TELNET
4853		Unassigned
4984	webyast	WebYast
6652		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