Common Computer Hardware (Physical) and Software (Virtual/Logical) Ports

In computer hardware, a port serves as an interface between the computer and other computers or peripheral devices. Physically, a port is a specialized outlet on a piece of equipment to which a plug or cable connects. Common computer hardware ports include -
    * RCA (Radio Corporation of America) - Audio/Video Applications
    * S-Video (Super Video) - Video
    * SVGA (Super Video Graphics Array) - Video
    * SCSI (Small Computer System Interface) - Storage
    * IDE (Integrated Drive Electronics) - Storage
    * SATA (Serial Advanced Technology Attachment) - Storage
    * eSATA (External SATA)
    * VGA (Video Graphics Array) - Monitor
    * DVI (Digital Visual Interface) - Monitor
    * RJ11 (Registered Jack) - Modem
    * HDMI (High Definition Multimedia Interface) - HD Video
    * Ethernet or RJ45 - Networking
    * Serial - Also knows as RS-232
    * Parallel - IEEE 1284
    * PS2 (Personal System2) - Keyboard and Mouse
    * USB (Universal Serial Bus) - Almost All Device
    * Firwire - Also Known as IEEE 1394 Interface - Camcorder

A software port (usually just called a 'port') is a virtual/logical data connection that can be used by programs to exchange data directly. The most common of these are TCP and UDP ports.

TCP ports use the Transmission Control Protocol. TCP is one of the main protocols in TCP/IP networks. Whereas the IP protocol deals only with packets, TCP enables two hosts to establish a connection and exchange streams of data. TCP guarantees delivery of data and that packets will be delivered in the same order in which they were sent. Guaranteed communication is the key difference between TCP and UDP.

UDP ports use the Datagram Protocol, a communications protocol for the Internet network, transport, and session layers. Like TCP (Transmission Control Protocol), UDP is used with IP (the Internet Protocol) and makes possible the transmission of datagrams from one computer to applications on another computer, but unlike TCP, UDP is connectionless and does not guarantee reliable communication; it's up to the application that received the message to process any errors and verify correct delivery.

A port number is a 16-bit unsigned integer, thus ranging from 0 to 65535. The Internet Assigned Numbers Authority (IANA) is responsible for maintaining the official assignments of port numbers for specific uses. However, many unofficial uses of both well-known and registered port numbers occur in practice. The virtual ports are classified as follows -

Well Known Ports: 0 through 1023.
Registered Ports: 1024 through 49151.
Dynamic/Private : 49152 through 65535.

Port 20 –> TCP –> FTP (File Transfer Protocol)
Port 21 –> TCP –> FTP (File Transfer Protocol)
Port 22 –> TCP/UDP –> SSH (ssh,scp copy or sftp)
Port 23 –> TCP/UDP –> Telnet
Port 25 –> TCP/UDP –> SMTP (for sending outgoing emails)
Port 43 –> TCP –> WHOIS function
Port 53 –> TCP/UDP –> DNS Server (DNS lookup uses UDP and Zone transfers use TCP)
Port 69 –> TFTP
Port 70 –> TCP –> Gopher Protocol
Port 79 –> TCP –> Finger protocol
Port 80 –> TCP –> HTTP
Port 88 –> TCP –> Kerberos
Port 109 –> POP2
Port 110 –> TCP –> POP3 (for receiving email)
Port 111 –> TCP –> RPC (remote procedure call)
Port 119 –> TCP –> NNTP (Network News Transfer Protocol)
Port 123 –> UDP –> NTP
Port 137 -> TCP/UDP -> NetBIOS Name Service
Port 138 -> TCP/UDP -> NetBIOS Datagram Service
Port 139 -> TCP/UDP -> NetBIOS Session Service
Port 143 –> TCP/UDP –> IMAP4 Protocol (for email service)
Port 156 –> TCP/UDP –> SQL Service
Port 161 –> TCP –> SNMP
Port 179 –> TCP –> BGP (Border Gateway Protocol)
Port 194 –> TCP –> IRC
Port 220 –> TCP –> IMAP3
Port 389 –> TCP/UDP –> LDAP (Light Weight Directory Access Protol)
Port 401 –> TCP/UDP  –> UPS Uninterruptible Power Supply
Port 443 –> TCP –> Secure HTTP over SSL (https)
Port 445 –> TCP –> Microsoft-DS Active Directory, Windows shares
Port 464 –> TCP/UDP –> Kerberos Change/Set password
Port 465 –> TCP –> Secure SMTP (email) using SSL
Port 513 –> TCP –> Login
Port 513 –> UDP –> Who
Port 514 –> TCP –> Shell—used to execute non-interactive commands on a remote system
Port 514 –> UDP –> system log listener (Syslog)
Port 515 –> TCP –> Print Spooler
Port 517 –> UDP –> Talk
Port 543 –> TCP –> klogin, Kerberos login
Port 544 –> TCP –> kshell, Kerberos Remote shell
Port 546 –> DHCPv6 client
Port 547 –> DHCPv6 server
Port 554 –> TCP/UDP –> RTSP
Port 631 –> TCP –> IPP (Internet Printing Protocol)
Port 873 –> TCP –> rsync File Synchronisation Protocol
Port 901 –> TCP –> SWAT (Samba Web Administration Tool)
Port 989 –> TCP/UDP –> FTPS Protocol (data): FTP over TLS/SSL
Port 990 –> TCP/UDP –> Secure FTP using SSL
Port 991 –> TCP/UDP –> NAS (Netnews Administration System)
Port 992 –> TCP,UDP –> TELNET Protocol over TLS/SSL
Port 993 –> TCP –> Secure IMAP Protocol Over SSL (for emails)
Port 994 –> TCP –> IRCS (Internet Relay Chat Secure)
Port 995 –> TCP –> pop3s (Post Office Protocol Secure version 3)
Port 1433 –> TCP/UDP –> Microsoft SQL server port
Port 1521 –> TCP –> Oracle Database Default Listener, in future releases official
Port 1526 –> TCP –> Oracle database common alternative for listener
Port 2030 –> Oracle Services for Microsoft Transaction Server
Port 2049 –> TCP/UDP –> NFS (Network File System by Sun)
Port 2082 –> TCP –> CPanel default port
Port 2083 –> TCP –> CPanel over SSL
Port 2086 –> TCP –> CPanel Webhost Manager (default)
Port 2087 –> TCP –> CPanel Webhost Manager (with https)
Port 2095 –> TCP –> CPanel Webmail
Port 2096 –> TCP –> Cpanel secure webmail over SSL
Port 2483 –> TCP/UDP –> Oracle database listening for unsecure client connections to the listener, replaces port 1521
Port 2222 –> TCP –> DirectAdmin Server Control Panel
Port 2484 –> TCP/UDP –> Oracle database listening for SSL client connections to the listener
Port 3306 –> TCP/UDP –> MySQL Database Server
Port 3872 –> TCP –> Oracle Management Remote Agent
Port 4643 –> TCP –> Virtuosso Power Panel
Port 5432 –> TCP –> PostgreSQL Database Server
Port 6000 –> TCP –> X11
Port 7777 –> TCP –> Oracle Cluster File System 2
Port 8080 –> TCP –> HTTP port (alternative one for port 80)
Port 8087 –> TCP –> Plesk Control Panel Port (default)
Port 8443 –> TCP –> Plesk Server Control Panel over SSL
Port 9999 –> TCP –> Urchin Web Analytics
Port 10000 –> TCP –> Webmin Server Control Panel
Port 19638 –> TCP –> Ensim Server Control Panel