A port is a communication point where one or more computers in a network talk 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 officialy assigned by an organisation called IANA and ports are allocated to various needs to avoid confusion.
Port Types & Classification
Ports are classified into 3 main categories..
- Well Known Ports (Port numbers 0 — 1023)
- Registered Ports (Port numbers1024 — 49151)
- Private or Dynamic Ports (Port numbers 49152 — 65535)
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.
Registered Ports
The registered port numbers range from 1024-49151. Such ports are used by programs run by users in the system.
Private/Dynamic Ports
Private ports are not assigned for any specific purpose. its range are from range 49152?65535
Difference TCP vs UDP Protocol
|
TCP/IP Protocol
|
UDP Protocol
|
| 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. |
Commonly Used Port Numbers
The following port numbers are unofficial list of commonly used for linux/unix based servers.
| Port Number | Protocol |
Function
|
| 21 | TCP | FTP (File Transfer Protocol) |
| 22 | TCP/UDP | SSH (ssh,scp copy or sftp) |
| 23 | TCP/UDP | Telnet |
| 25 | TCP/UDP | SMTP (for sending outgoing emails) |
| 43 | TCP | WHOIS function |
| 53 | TCP/UDP | DNS Server (Domain name service for DNS requests) |
| 67 68 |
UDP TCP |
DHCP Server DHCP Client |
| 70 | TCP | Gopher Protocol |
| 79 | TCP | Finger protocol |
| 110 | TCP | POP3 (for receiving email) |
| 119 | TCP | NNTP (Network News Transfer Protocol) |
| 143 | TCP/UDP | IMAP4 Protocol (for email service) |
| 194 | TCP | IRC |
| 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) |
| 2095 | TCP | Cpanel Webmail |
| 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 |
More unofficial list of ports and assignments s available here
Official ports and its assignments are published at the IANA website.
Note: The above published ones are unofficial list compiled from various sources.