451 Cray Network Semaphore server - System Port

451 is a System Port. Transport Protocol TCP UDP , 451 Service Name sfs-smp-net, Service Name Description: Cray Network Semaphore server.

Port	Protocol	Service Name	Description	Source
451	TCP UDP	sfs-smp-net	Cray Network Semaphore server	IANA
451	TCP UDP	sfs-smp-net	Cray Network Semaphore server	bekkoame

Port	Service Name	Description
884		Unassigned
1216	etebac5	ETEBAC 5
1342	esbroker	ESBroker
1446	ora-lm	Optical Research Associates License Manager
1567	jlicelmd	jlicelmd
3689	daap	Digital Audio Access Protocol (iTunes)
3787	fintrx	Fintrx
3869	ovsam-mgmt	hp OVSAM MgmtServer Disco
4116	smartcard-tls	smartcard-TLS
6175		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