581 Bundle Discovery Protocol - System Port

581 is a System Port. Transport Protocol TCP UDP , 581 Service Name bdp, Service Name Description: Bundle Discovery Protocol.

Port	Protocol	Service Name	Description	Source
581	TCP UDP	bdp	Bundle Discovery Protocol	IANA
581	TCP UDP	bdp	Bundle Discovery Protocol	bekkoame

Port	Service Name	Description
2176	rapi	Microsoft ActiveSync Remote API
2725	msolap-ptp2	MSOLAP PTP2
2994	veritas-vis2	VERITAS VIS2
3015	nati-dstp	NATI DSTP
4092	ewdgs	EminentWare DGS
5771	netagent	NetAgent
5835		Unassigned
6076	msft-dpm-cert	Microsoft DPM WCF Certificates
7019	doceri-ctl	doceri drawing service control
7223		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