77 any private RJE service - System Port

77 is a System Port. Transport Protocol TCP UDP , 77 Service Name , Service Name Description: any private RJE service.

Port	Protocol	Description	Source
77	TCP UDP	any private RJE service	IANA
77		priv-rjs protocol which is considered unsafe by Google Chrome,Unofficial	wikipedia
77	TCP UDP	any private RJE service	bekkoame

Port	Service Name	Description
1767	cft-6	cft-6
2447	ovwdb	OpenView NNM daemon
3572	megaregsvrport	Registration Server Port
3617	sharp-server	ATI SHARP Logic Engine
4234	vrml-multi-use	VRML Multi User Systems
5059	sds	SIP Directory Services
6107	etc-control	ETC Control
6319		Unassigned
7020	dpserve	DP Serve
8447		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