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 (http)
465
TCP
Secure SMTP (email) using SSL
990
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 http)
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.

TCP UDP Ports