General ports of network

In computer networking, a port is a software construct serving as a communications endpoint in a computer's host operating system. The purpose of ports is to uniquely identify different applications or processes running on a single computer and thereby enable them to share a single physical connection to a packet-switched network like the Internet; they were unnecessary until computers became capable of executing more than one program at the same time. A port is always associated with an IP address of a host and the protocol type of the communication, and thus completes the destination or origination address of a communications session. A port is identified for each address and protocol by a 16-bit number, commonly known as the port number.

    20 & 21: File Transfer Protocol (FTP)
    22: Secure Shell (SSH)
    23: Telnet remote login service
    25: Simple Mail Transfer Protocol (SMTP)
    53: Domain Name System (DNS) service
    80: Hypertext Transfer Protocol (HTTP) used in the World Wide Web
    110: Post Office Protocol (POP3)
    119: Network News Transfer Protocol (NNTP)
    143: Internet Message Access Protocol (IMAP)
    161: Simple Network Management Protocol (SNMP)
    194: Internet Relay Chat (IRC)
    443: HTTP Secure (HTTPS)
    465: SMTP Secure (SMTPS)