Configuring the web proxy with proxy auto-config (PAC) scripts

A proxy auto-config (PAC) file defines how web browsers and other user agents can choose the appropriate proxy server (access method) automatically for fetching a given URL.

The Smoothwall Filter supports built-in PAC scripts and custom PAC script templates. A built-in script is an auto configuration script that you can customize with additional settings such as exceptions. A custom script provides advanced functionality where you can use a script customized to suit your organization.

You can define the policy for each interface, by configuring the proxy address that the configuration script should direct clients to.

Procedures

On the WEB PROXY menu, under the Web proxy submenu, click Automatic configuration.

• To use a built-in script:
  1. Select the Built-in option.
  2. To not use the Smoothwall Filter when connecting to local addresses, select the Bypass proxy server for local addresses option.
     • Uses the Smoothwall Filter when connecting to local addresses. It makes users’ browsers bypass the Smoothwall Filter proxy if the address is a host name only, for example: myhostname. Browsers do not bypass the Smoothwall Filter proxy if the address is a fully qualified domain name (FQDN) for example: myhostname.example.local.
  3. So that the the Smoothwall Filter proxy uses its domain name instead of IP addresses in the configuration file, select the Refer to the proxy by domain name option.
     • Makes the Smoothwall Filter proxy use its domain name instead of IP addresses in the configuration file. Before turning on this option, make sure that you have a valid DNS configuration that resolves correctly for this host name. This option must be selected when using Kerberos authentication to use proxy automatic configuration.
  4. In the Exception domains and IP addresses box, enter an IP address, IP address range, network address or hostname that users might access directly. For example:
     • 192.168.0.1
     • 192.168.0.1-192.168.0.254
     • 192.168.0.0/24
     • hostname.local
  5. Optionally, click Advanced » and in the Exception regular expression domains box, enter one regular expression domain per line that users might access directly.

     • In the example, this would turn off usage of the Smoothwall Filter for youtube.com, ytimg.com and subdomains such as www.youtube.com; but not, for example, fakeyoutube.com.

       For example:

       • ^(.*\.)?youtube\.com$
       • ^(.*\.)?ytimg\.com$
  6. Click Save. The Smoothwall creates the script and makes it available at: http://Your_System_IP_address/proxy.pac.
• To use a custom script:
  1. Select the Custom script template option.
  2. Click Download, use the built-in template as starting point for creating a custom script, and then save the script to a suitable location.
  3. Edit the file and save it with another name.
  4. Click Choose Files, find the script and click Upload. The script is available at: http://Your_System_IP_address/proxy.pac.
• To manage the configuration script:
  • Under the Manage configuration script policy section, from the Interface list, select the address that the configuration script should direct clients to and click Save.