550 new-who - System Port | Service Name:new-rwho

550 is a System Port. Transport Protocol TCP UDP , 550 Service Name new-rwho, Service Name Description: new-who.

Port	Protocol	Service Name	Description	Source
550	TCP UDP	new-rwho	new-who	IANA
550	TCP UDP		new-rwho, new-who,Official	wikipedia
550	TCP UDP	new-rwho	new-who	bekkoame

Port	Service Name	Description
473	hybrid-pop	hybrid-pop
659		Removed
689	nmap	NMAP
782		Unassigned
1559	web2host	web2host
1686	cvmon	cvmon
2249	rfmp	RISO File Manager Protocol
3911	prnstatus	Printer Status Port
3935	sdp-portmapper	SDP Port Mapper Protocol
4116	smartcard-tls	smartcard-TLS

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