A socket is the end point of a two way communication between two systems running over a network. When two or more processes communicate over a network, they communicate using Sockets. A port implies an unsigned integer that uniquely identifies a process running over a network. The following are some of the well known port numbers distinguished by the type of services that they provide:

·         HTTP                 80

·         Telnet                23

·         SMTP                 25

·         SNPP                 444

·         DNS                  53

·         FTP (Data)          20

·         FTP (Control)      21