161 SNMP - System Port | Service Name:snmp

161 is a System Port. Transport Protocol TCP UDP , 161 Service Name snmp, Service Name Description: SNMP.

Port	Protocol	Service Name	Description	Source
161	TCP UDP	snmp	SNMP	IANA
161	UDP		Simple Network Management Protocol (SNMP),Official	wikipedia
161	UDP		Simple Network Management Protocol (SNMP)	Apple.com
161	TCP UDP	snmp	SNMP	bekkoame

Port	Service Name	Description
3049	nsws	NSWS
3478	stun	Session Traversal Utilities for NAT (STUN) port
5106		Unassigned
5202	targus-getdata2	TARGUS GetData 2
5432	postgresql	PostgreSQL Database
5456	apc-5456	APC 5456
5568	sdt	Session Data Transport Multicast
6231		Unassigned
7203		Unassigned
7507		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