High Level Settings

Defined Ports Tab

Overview of Zone Security Options

Overview of High Level Security

The Defined Ports tab shows which standard ports are open to incoming and outgoing traffic.

 

A check mark on the tab indicates the port is open to traffic in that direction; a port with no check mark is closed.

Why should I control open ports?

Certain ports must be open for routine Internet communication, but an open port can be a potential entrance for an attacker. The dangers posed by an open port could range anywhere from leaking information about your computer to a Denial of Service attack that crashes your system.

 

It is recommended you open only the ports you need.

 

To follow is a list of each defined port, with its fixed setting in the High level and a short description of its purpose.

Note: Any port not defined here is closed. If you want to define additional ports:

Instead of High level settings, use Custom level settings and define additional ports on the Custom Ports tab.

 

Name

Port Range

Incoming

Outgoing

Name Description

DHCP

68

Allow

Allow

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

SSH

22

Block

Block

(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

Block

Block

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

Allow

Block

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

SMTPS

465

Block

Block

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

Allow

Allow

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

Block

Block

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

Telnet

23

Block

Allow

Allows a client to remotely connect to a Telnet server and get a remote terminal session.

FTP Data

20

Block

Block

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

Block

Block

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

NetBIOS

137-139

Block

Block

(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

Block

Allow

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

Allow

Allow

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

Block

Block

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

FTP

21

Block

Block

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

Allow

Allow

(Domain Name Server). Translates domain names to IP addresses and stores other information.

IMAP

143

Block

Block

(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

Block

Allow

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

Block

Block

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

Block

Block

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

LDAP

389

Block

Block

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

HTTP Alternate

8080

Block

Block

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

Block

Allow

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

 

Note: If you want to change these settings, instead of High level settings, use Custom level settings and either make selections on the Defined Ports tab or define additional ports on the Custom Ports. Also, the Low level and the Medium level have different settings for port access.