717 Unassigned - System Port

717 is a System Port. Transport Protocol , 717 Service Name , Service Name Description: Unassigned.

Port	Protocol	Service Name	Description	Source
717			Unassigned	IANA
717	TCP UDP		Mac OS X RPC-based services, Used by NetInfo, for example	Apple.com

Port	Service Name	Description
803		Unassigned
966		Unassigned
1042	afrog	Subnet Roaming
1230	periscope	Periscope
1749	aspen-services	aspen-services
1845	altalink	altalink
2182	cgn-stat	CGN status
2341	xiostatus	XIO Status
2697	oce-snmp-trap	Oce SNMP Trap Port
4290	vrml-multi-use	VRML Multi User Systems

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