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.
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 |
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 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.