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
739		Unassigned
919		Unassigned
1595	radio	radio
1680	microcom-sbp	microcom-sbp
3214	jmq-daemon-1	JMQ Daemon Port 1
3278	lkcmserver	LKCM Server
4256	vrml-multi-use	VRML Multi User Systems
6437		Unassigned
7328	swx	The Swiss Exchange
8369		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