A port is a communication point where one or more computers in a network communicate with each other through a program or software. There are about 0-65535 ports assigned to do specific tasks in a PC. Most ports operate with TCP or UDP protocol.
Port numbers are assigned by an organisation called IANA and ports are allocated to various needs to avoid confusion.
Ports are classified into 3 main categories..
Well Known Ports
Well known ports are used by system or processes run by root or with specific previleges. The port numbers range from 0 to 1023.
The registered port numbers range from 1024-49151. Such ports are used by programs run by users in the system.
Private ports are not assigned for any specific purpose. its range are from range 49152–65535
|It is a connection oriented protocol||It is connectionless protocol which means it can send packets without establishing connection with the receiver at first.|
|It has flow control and error correction||It is error prone during transmission.|
|It is not fast and primarily used for data transmission like (http,ssh,smtp,ftp, mail etc.)||
It is fast and used mostly for audio and video streaming.
|Most common services requiring confirmation of delivery like http,ssh,smtp,ftp, mail etc. use TCP ports||
UDP ports are commonly used by services or programs that dont require the confirmation of delivery of packets. Most commonly used is DNS queries using UDP port 53.
Port numbers can also be specified using URL. For example port 80 is by default for HTTP. when you type a dot com in your browser the browser sends request in the form of http://www.domain.com:80/ to the server which responds and transfers data. Similarly port numbers can be specified in URL format as specified below depending on the application running with apache.
https://www.domain.com:443/ (Secure HTTP with SSL)
Note that the ports are specified with colon (:) in front.
The following port numbers are unofficial list of commonly used for linux/unix based servers.
|21||TCP||FTP (File Transfer Protocol)|
|22||TCP/UDP||SSH (ssh,scp copy or sftp)|
|25||TCP/UDP||SMTP (for sending outgoing emails)|
|53||TCP/UDP||DNS Server (Domain name service for DNS requests)|
|110||TCP||POP3 (for receiving email)|
|119||TCP||NNTP (Network News Transfer Protocol)|
|143||TCP/UDP||IMAP4 Protocol (for email service)|
|389||TCP/UDP||LDAP (light weight directory access)|
|443||TCP||Secure HTTP over SSL (https)|
|465||TCP||Secure SMTP (email) using SSL|
|990||TCP/UDP||Secure FTP using SSL|
|993||TCP||Secure IMAP protocol over SSL (for emails)|
|1433||TCP/UDP||Microsoft SQL server port|
|2082||TCP||Cpanel default port|
|2083||TCP||Cpanel over SSL|
|2086||TCP||Cpanel Webhost Manager (default)|
|2087||TCP||Cpanel Webhost Manager (with https)|
|2096||TCP||Cpanel secure webmail over SSL|
|2222||TCP||DirectAdmin Server Control Panel|
|3306||TCP/UDP||MySQL Database Server|
|4643||TCP||Virtuosso Power Panel|
|5432||TCP||PostgreSQL Database Server|
|8080||TCP||HTTP port (alternative one for port 80)|
|8087||TCP||Plesk Control Panel Port (default)|
|8443||TCP||Plesk Server Control Panel over SSL|
|9999||TCP||Urchin Web Analytics|
|10000||TCP||Webmin Server Control Panel|
|19638||TCP||Ensim Server Control Panel|
Note: The above published ones are unofficial list compiled from various sources.
Official port numbers and assignments from IANA - http://www.iana.org/assignments/port-numbers
TCP and UDP Ports from Wikipedia - http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers
Trojan Port List - http://www.bekkoame.ne.jp/~s_ita/port/port1-99.html
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