Port Number Reference
TCP, UDP, and SCTP all use port numbers to identify the logical communications between hosts. The combination of a port and IP address identifies a TCP/UDP/SCTP Endpoint, and the endpoint pairs on either end of a "connection" make up a TCP/UDP/SCTP Conversation.
The concept of a TCP/UDP port is to provide several logical channels between the same IP hosts. When sending a packet, TCP/UDP multiplexes the data from separate applications over one IP "host to host transfer". While receiving, TCP/UDP demultiplexes the IP packets again, providing the received data to the applications interested in.
The addressing of this multiplexing/demultiplexing is done using the ports.
Port numbers are unsigned 16-bit integers, ranging from 0 to 65535. The IANA list of assigned port numbers has divided ports into three ranges:
0 through 1023: Well Known Ports
1024 through 49151: Registered Ports
49152 through 65535: Dynamic or Private Ports
Ports 1024 and above are also referred to as ephemeral ports.
Ports are officially registered with the IANA. Unofficial lists are maintained by many people, including the following:
A local list is maintained below: