Common Port Numbers Statistics
Data source - Service Name and Transport Protocol Port Number registry.
Number of entries in database - 14380.
Port numbers (16-bit numbers) are most widely used for defining applications and services on the Internet.
Typically combination of source and destination port numbers, together with the IP addresses of the systems that take part in the communication, uniquely identifies a session of a given transport protocol.
Port numbers are assigned based on three ranges:
- System Ports (0-1023)
- User Ports (1024-49151)
- Dynamic and/or Private Ports (49152-65535)
Service names are assigned on a first-come, first-served process.
Service names and port numbers are used to distinguish between different services that run over Transport Protocols:
- TCP(Transmission Control Protocol) - provides reliable, ordered, and error-checked delivery of a stream of octets (bytes) between applications running on hosts communicating via an IP network.
- UDP (User Datagram Protocol) - uses a simple connectionless communication model with a minimum of protocol mechanisms.
- SCTP (Stream Control Transmission Protocol) - protocol provides the message-oriented feature of the UDP, while ensuring reliable, in-sequence transport of messages with congestion control like the TCP.
- DCCP (Datagram Congestion Control Protocol) - implements reliable connection setup, teardown, Explicit Congestion Notification (ECN), congestion control, and feature negotiation.
There can be a situation when not just one service name is associated with a specific transport protocol and port, it is called "overloading".
There are three possible ways of overloading:
- By historical accident. Sounds very similar to some kind of legacy remnants and/or it "always been this way".
- When one service is an extension of another service.
- On purpose, to create replacement names to conform to the syntax.
There are 871 - Unassigned and 771 - Reserved (74% - UDP; 26% - TCP) ports.
