Ports are numbered resources that identify the protocol being used to transfer data over a network. Some common ports and their purposes include: Port 80 for HTTP, which is the basis of the World Wide Web. Port 22 for SSH, which allows for encrypted remote access and file transfers. Port 25 for SMTP, which is the main protocol for moving email on the Internet.

1. H I N D A L F A L A S I
1 0 A G
20 COMMON PORTS AND
THEIR PURPOSES

2. WHAT ARE PORTS?
• Most network protocols involve transferring data over
one or more ports, which are numbered resources on a
computer.
• The port number identifies the protocol being used.

3. PORT 1
TCP
Port Service Multiplexer
(TCPMUX)

4. PORT 5
Remote Job Entry (RJE)

5. PORT 7
ECHO

6. PORT 18
Message Send Protocol
(MSP)

7. PORT 20, 21
Protocol Common Server
Program(s)
Explanation
FTP oftpd,ProFTPD, Pure-
FTPd, vsftpd
FTP is an old protocol for
transferring files over a
network. It supports both
anonymous and
password-mediated
access.

8. PORT 22
Protocol Common Server
Program(s)
Explanation
SSH OpenSSH SSH is an encrypted
remote access tool. It
also supports file
transfers and encrypting
other protocols.

9. PORT 23
Protocol Common Server
Program(s)
Explanation
Telnet telnetd an old unencrypted
remote login protocol,
that can be a useful
network diagnostic tool.

10. PORT 25
Protocol Common Server
Program(s)
Explanation
SMTP Exim, Postfix, qmail,
sendmail
SMTP is the main
protocol for moving email
on the Internet.

11. PORT 42
Protocol Common Server
Program(s)
Explanation
DNS dnsmasq, named DNS enables computers
to look up an IP address
by providing a hostname,
or vice-versa.

12. PORT 67
Protocol Common Server
Program(s)
Explanation
BOOTP, DHCP dnsmasq, dhcpd BOOTP and DHCP
enable a computer on a
local network to help
automatically configure
other computers to use a
network.

13. PORT 80
Protocol Common Server
Program(s)
Explanation
HTTP Apache (HTTP) is the basis of
the World Wide Web
(WWW, or Web).

14. PORT 109, 110
Protocol Common Server
Program(s)
Explanation
POP2 and POP3 Courier, Cyrus, IMAP,
Dovecot, UW IMAP
This protocol enables a
recipient to initiate an
email transfer

15. PORT 118
Protocol Common Server
Program(s)
Explanation
SQL MySQL, PostgreSQL (SQL) is a network-
enabled database inter-
face language.

16. PORT 137, 139
Protocol Common Server
Program(s)
Explanation
SMB/CIFS Samba Microsoft uses the
(SMB)/ (CIFS) protocols
for file and printer
sharing, and Samba
implements these
protocols in Linux.

17. PORT 143, 200
Protocol Common Server
Program(s)
Explanation
IMAP Courier, Cyrus, IMAP, D IMAP makes it easier for
recipients to permanently
store and manage email
on the server computer

18. PORT 389
Protocol Common Server
Program(s)
Explanation
LDAP OpenLDAP a network protocol for
accessing directories,
which in this context are
a type of database.

19. PORT 443
Protocol Common Server
Program(s)
Explanation
HTTPS Apache This protocol is a secure
(encrypted) variant of
HTTP.

20. PORT 2049
Protocol Common Server
Program(s)
Explanation
NFS NFS (NFS) is a protocol, and
a server of the same
name, for file sharing
between Unix and Unix-
like OSs.