Name

Port Range

Name Description

DHCP

68

(Dynamic Host Configuration Protocol). Used to assign IP addresses and other parameters when a computer is added to a network.

SSH

22

(Secure Shell). Establishes a secure, encrypted channel between a local and a remote computer. Used for secure logins, file transfers, and port forwarding.

SMTP Submission

587

SMTP (Simple Mail Transfer Protocol) is a standard for outbound e-mail transport.

This port is used to transmit e-mail from a client to a mail server. Can also act as an alternate to port 25.

POP3

110

(Post Office Protocol 3). Used to retrieve e-mail messages from a mail server. Supported by most e-mail clients and servers.

SMTPS

465

SMTP (Simple Mail Transfer Protocol) is a standard for outbound e-mail transport.

This port is used to transmit e-mail with authentication and encryption from a client to a mail server and between mail servers.

HTTPS

443

HTTP (HyperText Transfer Protocol) is the basis of the Web and is used to transfer and display HTML files.

This port is used for secure transactions, such as payments, and provides authentication and encryption.

NNTP

119

(Network News Transfer Protocol). Used for reading and posting Usenet articles and transferring news among news servers.

Telnet

23

Allows a client to remotely connect to a Telnet server and get a remote terminal session. Communication is unencrypted and not secure.

FTP Data

20

FTP (File Transfer Protocol) is commonly used for exchanging files over the Internet.

The FTP server listens on port 21 for incoming connection from FTP clients. Then, the server binds on this port before connecting to the client.

Whois

43

Used to provide information about networks, domains, and hosts.

NetBIOS

137-139

(Network Basic Input/Output System). Allows applications on separate computers to communicate over a local area network.

Used for Windows File and Print Sharing.

SMTP

25

SMTP (Simple Mail Transfer Protocol) is a standard for outbound e-mail transport.

This port is used to transmit e-mail from a client to a mail server and between mail servers.

HTTP

80

HTTP (HyperText Transfer Protocol) is the basis of the Web and is used to transfer and display HTML files.

This port is used to transfer information over the Web.

IRC

194

(Internet Relay Chat). Facilitates instant communication, such as instant messaging, over the Internet.

FTP

21

FTP (File Transfer Protocol) is commonly used for exchanging files over the Internet.  

The FTP server listens on this port for incoming connection from FTP clients. Then, the server binds on port 20 before connecting to the client.

DNS

53

(Domain Name Server). Translates domain names to IP addresses and stores other information. You may have problems browsing the Internet if this port is closed.

IMAP

143

(Internet Message Access Protocol). Used to retrieve e-mail messages from a mail server. Supported by most e-mail clients and servers.

Remote Desktop

3389

Used for Remote Desktop connections that give access to a computer while at a remote computer.

See also Settings window > Advanced section > Remote Desktop connections field.

MSRPC

135

The RPC (Remote Procedure Call) is used to support applications with components located on different machines.

This port is used by Active Directory and Microsoft Exchange mail servers.

SMB

445

Use to share files, printers, serial ports, and miscellaneous communications between computers on a network.

LDAP

389

(Lightweight Directory Access Protocol). Used to query a server and access a directory listing.

HTTP Alternate

8080

HTTP (HyperText Transfer Protocol) is the basis of the Web and is used to transfer and display HTML files.

This port is used when running a second web server on the same machine or for a web proxy and caching serve.

NTP

123

(Network Time Protocol). Used to synchronize the clocks of computers on a network.