174 MAILQ - System Port | Service Name:mailq

174 is a System Port. Transport Protocol TCP UDP , 174 Service Name mailq, Service Name Description: MAILQ.

Port	Protocol	Service Name	Description	Source
174	TCP UDP	mailq	MAILQ	IANA
174	TCP UDP	mailq	MAILQ	bekkoame

Port	Service Name	Description
660	mac-srvr-admin	MacOS Server Admin
1824	metrics-pas	metrics-pas
2507	spock	spock
2593	mns-mail	MNS Mail Notice Service
3581	kfxaclicensing	Ascent Capture Licensing
4521		Unassigned
4968		Unassigned
5929		Unassigned
6037	x11	X Window System
6322	emp-server2	Empress Software Connectivity Server 2

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