What are ports and protocols ?

As per its word definition, a protocol is a set of rules. In computer networking, a protocol defines a standard way for computers to exchange information. Most common protocols used in computer networks and the internet are TCP (Transmission Control Protocol), UDP (User Datagram Protocol), and IP (Internet Protocol).

A port in computer networking is a logical access channel for communication between two devices. Bi-directional communications and more complex connections may use multiple ports (channels) simultaneously.

Data on the Internet is organized into standard TCP or UDP packets. Network clients use different ports (or channels) to transfer this data. Generally one port is used to send data and another to receive it, so packets don't collide. The port number (and the destination IP address) is included as part of the header each packet is given. Ports range from 1 to 65535 for the TCP and UDP protocols.

Port numbers are generally divided into three ranges:

1. The Well Known ports: 0 to 1023
2. The Registered ports: 1024 to 49151
3. The Dynamic and/or Private ports: 49152 to 65535

Note: A list of all IANA assigned port numbers and their associated services can be found on their website. We also maintain a large database of all port assignments, known vulnerabilities, applications that use them and more here: SG Ports database