wpad

WPAD

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In this article, we will explain about WPAD and its settings, how to use it and also tell how to configure Content Gateway as Web Proxy Auto discovery Server, for this you should read this article.

Definition Web Proxy Auto discovery

WPAD is short for Web Proxy Auto discovery Protocol, a method used by it to locate the URL of a configuration file using the DHCP or DNS discovery methods. Once the configuration file is detected and downloaded, it is executed then determine the proxy for the specified URL.

DHCP gets higher priority than DNS: if DHCP provides a Web Proxy Autodiscovery URL, no DNS lookup is performed. It only works with DHCPv4. And in DHCPv6, no WPAD-Option is defined. Firefox does not support DHCP, only DNS works on Windows and ChromeOS and other platforms

When constructing the query packet, the DNS lookup removes the first part of the domain name (client host name) and replaces it in Web Proxy Auto discovery. Then, it goes “up” the hierarchy, removing more parts of the domain name, until it finds the WPAD PAC file or leaves the current organization. The browser takes a guess as to where the organization’s boundaries are. This estimate is often true for domains such as ‘company.com’ or ‘university.edu’, but false for ‘company.co.uk’.

For DNS, the path to the configuration file is wpad.dat. Whereas for DHCP protocol, any URL is usable. (Note that the MIME type of the configuration file must be “application/x-ns-proxy-autoconfig”.)

What is WPAD settings and how to use it?

Internet Explorer version 7 onwards allows Web Proxy Auto discovery to automatically detect a server that it would have supplied with proxy server configuration settings. Clients do not need to configure their browsers to send requests to proxy servers: a single server provides settings to all clients on the network. When an Internet Explorer version of the browser starts, it searches for a WPAD server that supplies it with proxy server configuration settings. This hostname links Web Proxy Auto discovery to the current fully qualified domain name. For example, a client in x.y.company.com searches for a it server at wpad.x.y.company.com. Failing that, the browser removes the bottommost domain and tries again; For example, it tries wpad.y.company.com. When the browser detects a Web Proxy Auto discovery server or reaches the third level domain, wpad.company.com, it stops searching.

How to configure content gateway as WPAD server?

If you have a wpad.dat file, you can replace the wpad.dat file located in the Content Gateway configuration directory to your existing file. here follow these steps:

  • First log on to Content Gateway Manager and go to Configure > Content Routing > Browser Auto-configuration > WPAD to display the wpad.dat file.
  • The wpad.dat file displays a Web Proxy Auto discovery settings area:
    • If you copied the wpad.dat file, the file contains your proxy configuration settings. Check that settings and make changes if necessary.
    • If you have not copied the existing wpad.dat file to the Content Gateway configuration directory (/opt/WCG/config), the WPAD Settings area is empty and script has to be entered in it.
  • Then click on apply.
  • Go to Configure > Networking > ARM.
  • In the Network Address Translation (NAT) section, click Edit File to add a special remap rule to the ipnat.conf file.
  • Then enter the information in the fields provided, and then click Add:
    • In the Ethernet interface field, enter the network interface that the browser receives the Web Proxy Auto discovery request.
    • From the Connection Type drop-down list, choose tcp.
    • Enter the IP address of the content gateway server that will be resolved by the local name server to the WPAD server name.
    • In the Destination CIDR field (optional), enter the CIDR mask value. Enter 32 for the IPv4 format if the destination IP. and enter 128 for the IPv6 destination IP.
    • In the Destination Port field, enter 80.
    • Enter the same IP address in the Destination IP field that you entered in the Destination IP field.
    • In the Redirect destination port field, enter 8083.
    • In the User Protocol field (optional), select DNS.
  • Click Add button.
  • Use the LEFT ARROW KEYS to move the new rule to the first line in the file.
  • Click Apply and Close.
  • Then click on Configure > My Proxy > Basic > Restart to General.
  • WPAD Web Proxy Auto discovery Protocol A system that makes it easy for organizations to configure multiple web browsers inside their networks.
  • And they are able to download files from the Internet.