Web Proxy Auto Discovery (WPAD)

The Web Proxy Auto-Discovery Protocol (WPAD) feature enables Poly phones to locate the URL of a Proxy Auto-Configuration (PAC) file you configure.

You can configure WPAD using configuration parameters on your provisioning server, DHCP Option 252, or the DNS-A protocol mechanism to discover the PAC file location. When using a provisioning server or DHCP, the phone looks for the file name you specify. If using DNS-A, the phone looks only for the wpad.dat file.

PAC File Search Priority

Poly phones search for PAC files in the following priority order:
  • Provisioning server. Example: feature.wpad.curl="http://server.domain.com/proxy.pac
  • DHCP Option 252. For instructions, see Creating an Option 252 entry in DHCP on Microsoft TechNet: https://technet.microsoft.com/en-us/library/cc995090.aspx
  • DNS-A. For instructions, see Creating a WPAD entry in DNS on Microsoft TechNet: https://technet.microsoft.com/en-us/library/cc995062.aspx
    Note: If the proxies you configure in the PAC file or configuration file are either invalid or unreachable with a working fallback proxy, the time to register with Skype for Business is delayed and the responsiveness of features that support WPAD degrade.

Supported HTTP/HTTPS Web Proxy Services

When the web proxy server is successfully configured and operational, the phones route the following HTTP/HTTPS web proxy services to the web proxy server:

Generic Services
  • HTTP/HTTPS Provisioning
  • Core File Upload

Skype for Business Services

  • Registration Services
  • Address Book Service (ABS)
  • Location Information Server (LIS)
  • Device Update (To ensure reliable software updates, device update is direct in case a proxy is not available.)
  • Server Log Upload
  • Exchange Web Services

PAC File Search Priority

When using automatic web proxy discovery, you can configure Poly phones to discover the Proxy Auto-Configuration (PAC) file location on your provisioning server, using DHCP Option 252, or using the DNS-A protocol mechanism.

Poly phones search for PAC files in the following priority order.:
  • Provisioning server Example: feature.wpad.curl="http://server.domain.com/proxy.pac
  • DHCP Option 252 For instructions, see Creating an Option 252 entry in DHCP on Microsoft TechNet: https://technet.microsoft.com/en-us/library/cc995090.aspx
  • DNS-A For instructions, see Creating a WPAD entry in DNS on Microsoft TechNet: https://technet.microsoft.com/en-us/library/cc995062.aspx
    Note: If the proxies you configure in the PAC file or configuration file are either invalid or unreachable with a working fallback proxy, the time to register with Skype for Business is delayed and the responsiveness of features that support web proxy auto-discovery degrade.

When using a provisioning server or DHCP, the phone looks for the file name you specify. If using DNS-A, the phone looks only for the wpad.dat file.

If your configuration includes automatically downloading a PAC file, there must be an expiration associated with the file so the system knows when to download a new one. Make sure your PAC file server includes an Expires header in its HTTP response (for example, Expires: Wed, 30 Oct 2016 09:30:00 GMT).

Supported HTTP/HTTPS Web Proxy Services

When the web proxy server is successfully configured and operational, Poly phones route specific HTTP and HTTPS services to the web proxy server.

The phones route the following services to the web proxy server:

Generic Services
  • HTTP/HTTPS Provisioning
  • Core File Upload
Skype for Business Services
  • Registration Services
  • Address Book Service (ABS)
  • Location Information Server (LIS)
  • Device Update (To ensure reliable software updates, device update is direct in case a proxy is not available.)
  • Server Log Upload
  • Exchange Web Services

Configure Web Proxy Access Manually

Manually configure web proxy access for Poly phones that cannot use automatic web proxy discovery.

For Poly Trio 8500 and 8800 with MSTeams and Zoom Base Profiles, automatic web proxy discovery is not supported, so you must manually configure your phones to access the web proxy server.

Procedure

  1. Set the parameter feature.wpad.enabled to 1.
  2. Enter the web proxy server address for the parameter feature.wpad.proxy.
    You can specify multiple proxies using this parameter by separating each with a semicolon the same way you would specify them in the PAC file.
    PROXY 0.10.1.1:8080;
    PROXY 10.12.2.1:8080

Configure Proxy-Specific Credentials for Users

Poly phones support Digest and NTLM Authentication mechanisms to authenticate with a proxy server. This enables you to manually configure proxy-specific credentials common to all users using Basic Authentication.

Note: When users sign into Skype for Business accounts, the phone uses the Skype credentials to sign into the web proxy.
Note: You cannot set proxy-specific credentials for Poly Trio systems set to the Teams or Zoom Base Profiles.

Procedure

  • Configure the following parameters on a provisioning server:
    • feature.wpad.proxy.username
    • feature.wpad.proxy.password

View WPAD Diagnostic Information

When the web proxy server is successfully configured and operational, you can access important WPAD diagnostic information to track HTTP and HTTPS traffic flowing via the proxy you configured.

From the system web interface (Web Configuration Utility), you can download the PAC file and view the following diagnostic information on a per-phone basis:

  • PAC file fetch is successful
  • Configured method used to fetch the PAC file and source URLs
  • DNS domain if configured
  • PAC file expiry details
  • Exchange and upload proxy

Procedure

  1. Enter your phone’s IP address into a web browser.
  2. Select Admin as the login type, enter the administrator password, and select Submit.
  3. Go to Diagnostics > Skype for Business Status > WPAD.

WPAD Configuration Parameters

The following parameters configure the Web Proxy Auto Discovery (WPAD) feature.

feature.wpad.enabled
Set to enable web proxy.

0 (default) - Disables web proxy.

1 - Enables web proxy. Default for the Skype Base Profile.

Change causes system to restart or reboot.

feature.wpad.curl

Enter the PAC file location.

Change causes system to restart or reboot.

Note: Not supported in MSTeams and Zoom Base Profiles.
feature.wpad.proxy

Configure the web proxy server address. If you configure this parameter with a proxy address, the phones do not discover DHCP or DNS-A or fetch the PAC file even if you configure a PAC file location using feature.wpad.curl.

0-255 characters

You can specify multiple proxies using this parameter by separating each with a semicolon the same way you would specify them in the PAC file. For example:

PROXY 0.10.1.1:8080;
PROXY 10.12.2.1:8080

Change causes system to restart or reboot.

feature.wpad.proxy.username

Enter the user name to authenticate with the proxy server.

0-255

Change causes system to restart or reboot.

Note: Not supported in MSTeams and Zoom Base Profiles.
feature.wpad.proxy.password

Enter the password to authenticate with the proxy server.

The credentials you can use depend on how authentication is enabled on the proxy server. You can use administrator or user credentials. If Skype for Business Active Directory is integrated with the proxy server, you do not need to configure user name or password credentials.

0-255

Change causes system to restart or reboot.

Note: Not supported in MSTeams and Zoom Base Profiles.