SOCKSClosed SOCKetS is a versatile Internet protocol that allows client-server applications to transparently use the services of a network firewall. It is used by many client applications behind a firewall to communicate with hosts on the Internet. Examples are IRCClosed Internet Relay Chat/Instant Messaging clients, FTPClosed File Transfer Protocol clients, and Windows SSHClosed Secure Shell/Telnet clients. Those clients behind a firewall wanting to access exterior servers connect to a SOCKS proxy server instead. This proxy server controls the eligibility of the client to access the external server and passes the request on to the server. Your client application must explicitly support the SOCKS 4 or SOCKS 5 protocol versions.

The default port for SOCKS is 1080. Almost all clients have implemented this default port setting, so it normally does not have to be configured. The differences between SOCKS and NAT are that SOCKS also allows "bind" requests (listening on a port on behalf of a client—a feature which is supported by very few clients only) and that SOCKS 5 allows user authentication.

When enabling the SOCKS proxy, you must define one or more networks which should have access to the proxy. When you require user authentication, you can also select the users or groups that should be allowed to use the SOCKS proxy.

Note – Without user authentication, the SOCKS proxy can be used with both the SOCKS 4 and SOCKS 5 protocols. When user authentication is selected, only SOCKS 5 will work. If you want the proxy to resolve hostnames in SOCKS 5 mode, you must also activate the DNSClosed Domain Name Service proxy, because otherwise DNS resolution will fail.

To configure the SOCKS proxy, proceed as follows:

  1. On the SOCKS Proxy tab, enable the SOCKS proxy.

    Click the toggle switch.

    The toggle switch turns amber and the SOCKS Proxy Options area becomes editable.

  2. Specify the following settings:

    Allowed Networks: Add or select the networks that should be allowed to use the SOCKS proxy. For how to add a network definition, see Definitions & Users > Network Definitions > Network Definitions.

    Enable user authentication: If you select this option, users must provide a username and password to log in to the SOCKS proxy. Because only SOCKS 5 supports user authentication, SOCKS 4 is automatically disabled.

    Allowed Users: Select the users or groups or add new users that should be allowed to use the SOCKS proxy. For how to add new users or groups, see Definitions & Users > Users & Groups > Users.

  3. Click Apply.

    Your settings will be saved.

    The switch turns green.