Setting Up Forward Proxy with WPAD

Figure 67 provides a visual map for the information in this section.

NOTE:  The letters in Figure 67 are referenced in the table that follows. The addresses shown are for illustration purposes only. You will need to substitute actual addresses for your network.

Figure 67

You can set up forward proxy and WPAD services as explained in the following table:

To Do This Notes

Ensure your basic network configuration is complete
  1. See Basic Network Configuration Setup.

Enable forward proxy and WPAD services on the appliance
  1. In the browser-based tool, click Cache > Client Accelerator > Enable Client Acceleration (Forward Proxy).
  2. In the Proxy IP Addresses list, check the IP addresses that forward proxy services will be available on.
  3. Enter the port that Excelerator will receive and process forward proxy requests on. (The default is 8080.)
  4. Check Enable Automatic Proxy Configuration (WPAD).
  5. Click Apply.

See A in Figure 67.

The WPAD listener port number is 80, which is the default port for transparent proxy and Web server accelerators. Because proxy services take precedence, you cannot have another service that uses port 80 configured on an IP address that needs to accept WPAD requests.

After Excelerator has been enabled for WPAD, it will automatically listen for WPAD requests on all IP addresses enabled for forward proxy services as long as the addresses are not also enabled for a service that uses port 80.

For more information, see Client Accelerator Tab.

Configure your network to provide the required information to requesting browsers

(To work with WPAD services, you must have Internet Explorer 5 or other browsers on your network that rely on DNS, SLP, DHCP, or other protocols.)

Procedures for configuring Web protocols to work with WPAD vary.

Information and instructions are found on the Web. A sample site is listed in the Notes column.

After you understand the requirements for your network and the browsers being used, configure your network to provide WPAD services to network browsers.

For more information on using auto-config files like WPAD.DAT, see "Navigator Proxy Auto-Config File Format" on the Web.

The WPAD RFC draft might also help you understand your network setup requirements. See a draft copy on the Web.

Enable the client browsers to request and use the WPAD information

Read the notes to understand which of the following applies to your browsers.

To configure Netscape Communicator 4.5 to access an appliance configuration file:

  1. Click Edit > click Preferences > check Advanced > click Proxies > check Automatic Proxy Configuration.
  2. Enter the URL for the WPAD-enabled appliance's WPAD file as follows: http://IP_address/wpadxx.dat, where IP_address is the appliance's IP address and xx is the file numbering convention explained in Customizing Web Proxy Auto-Discovery.

To configure Internet Explorer 5 to use automatic detection:

  1. Click Tools > Internet Options > Connections > LAN Settings.
  2. Check Automatically Detect Settings.

See B in Figure 67.

Excelerator sends a WPAD configuration file to requesting browsers. This file contains proxy service information for the network.

Procedures for configuring browsers to request and use WPAD information vary. Internet Explorer supports both automatic detection of WPAD settings and automatic configuration of files retrieved from known URLs. Netscape supports only the latter WPAD configuration method.

Internet Explorer's automatic detection feature requires that the names database on the DNS server contain a wpad.domain.com entry that resolves to the appliance's forward proxy address. On Windows 98 clients, you must add the same DNS entry to the HOSTS file in the WINDOWS directory. If the HOSTS file does not exist, you can either copy HOSTS.SAM to HOSTS or create a new HOSTS file.

Excelerator automatically creates a WPADxx.DAT file for each IP address configured for client acceleration. You can customize each address' file using FTP, or you can provide a customized file named WPAD.DAT that Excelerator will use for all WPAD requests regardless of the IP address on which the request was received.

For more information on appliance WPAD capabilities, see Customizing Web Proxy Auto-Discovery.