PAC file function support



This article describes extended PAC file functions that are not supported in Atlas Platform Release 3.11, but are supported in Release 3.12. 

When you use a PAC file with the Secure Web Stack policy, Blue Cedar processes the file according to the de facto standard published by Netscape in 1996. This specification details the functionality of available PAC file functions, and can be found at To our knowledge, all major browsers implement the same functionality.

After the publication of the functional specification, Microsoft added several methods mostly to deal with multiple IP addresses an interface can be assigned and support for IPv6. These methods are not part of the original specification, and are supported in some browsers, but not others. For further details, see Extensions to the Navigator Proxy Auto-Config File Format specification

In addition, a commonly known JavaScript function, alert() is not supported in Release 3.11 either. The alert() function is not specified in the original PAC specification, although it may be supported in several browsers.    


Atlas Platform Release 3.11 currently supports most of the additional functions except for the following. These functions are supported in Release 3.12.

Extended functions to the PAC file specification:

PAC file extensionSourceBlue Cedar supported


sortIpAddressList()MicrosoftNo. PAC evaluation fails.
isInNetEx()MicrosoftNo. PAC evaluation fails.
getClientVersion()MicrosoftNo. PAC evaluation fails.
alert()JavaScriptNo. PAC evaluation proceeds, but ignores the alert message.

When a PAC file cannot be evaluated, all outbound client traffic is blocked. 


To avoid PAC file failures in release 3.11, please avoid using the unsupported functions, or upgrade to 3.12.