540 uucpd - System Port | Service Name:uucp

540 is a System Port. Transport Protocol TCP UDP , 540 Service Name uucp, Service Name Description: uucpd.

Port	Protocol	Service Name	Description	Source
540	TCP UDP	uucp	uucpd	IANA
540	TCP		UUCP (Unix-to-Unix Copy Protocol),Official	wikipedia
540	TCP UDP	uucp	uucpd	bekkoame

Port	Service Name	Description
837		Unassigned
2287	dna	DNA
2364	oi-2000	OI-2000
3415	bcinameservice	BCI Name Service
4524		Unassigned
4614		Unassigned
4651		Unassigned
4994		Unassigned
5248	caacws	CA Access Control Web Service
5656		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