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.