Proxy pacfile hosting without need for Webservers using iFiles on v11

Problem this snippet solves:

The following is an iRule that allows the F5 to serve a proxy pac file to a client without the need of hosting it on a web server or the proxy itself.

Simply create the iRule and associate it to a virtual address running a specific port that has no pools.

Definition

What the heck is a pacfile? Well it's a javascript file that defines how web browsers and other user agents can automatically choose the appropriate proxy server (access method) for fetching a given URL. So you might have specific sites that go through a proxy and some sites that do not. The pac file can do this for you.

To read up more about it you can go to the following links: http://en.wikipedia.org/wiki/Proxy_auto-config http://www.craigjconsulting.com/proxypac.html

Now back to the configuration...

How to use this snippet:

Example

VIP: 192.168.1.20: 80 TCP
Domain: Proxypacfile.intranet.com --> 192.168.1.20

Just set your browser up to use the automatic configuration script:

http://proxypacfile.intranet.com/proxy.pac

You can also set to other ports

Example:

VIP: 192.168.1.21: 9090 TCP
Domain: Proxypacfile2.intranet.com --> 192.168.1.21

Just set your browser up to use the automatic configuration script:

[http://proxypacfile2.intranet.com:9090/proxy.pac] (http://proxypacfile2.intranet.com:9090/proxy.pac)

iFile Configuration:

1) Create a pacfile for example called "proxy.pac". Contained in the file could be the following logic

function FindProxyForURL(url, host) {

         if (isPlainHostName(host))
         return "DIRECT";

         if (shExpMatch(url, "http://10.*")||
         shExpMatch(url, "https://10.*")||
         shExpMatch(url, "ftp://10.*")||
         shExpMatch(url, "http://localhost*")||
         shExpMatch(url, "https://localhost*")||
         shExpMatch(url, "http://127.0.0.1*")||
         shExpMatch(url, "https://127.0.0.1*")||
         shExpMatch(url, "http://172.*")||
         shExpMatch(url, "https://172.*")||
         shExpMatch(url, "ftp://172.*"))
         return "DIRECT";

      if (dnsDomainIs(host, ".extranet.com")||
         dnsDomainIs(host, ".extranet2.com"))
         return "Proxy yourproxy.domain.com:8080";
         
         if (dnsDomainIs(host, ".intrant.com")||
         dnsDomainIs(host, ".intranet2.com"))
         return "DIRECT";
        
      return "PROXY yourproxy.domain.com:8080";
      }
   }
   

2) Now you are ready to upload the files. This is done in System > File Management--> iFile List --> Import

NOTE: Keep in mind iFiles maximum size is 4M

3) Now create a reference of the ifile. This is done by going to Local Traffic->iRules->iFile List. Fill in the information using the same name as the file itself to make this easy.

4) Now all you need is to create the irule itself

Code :

when HTTP_REQUEST {
   switch -glob [string tolower [HTTP::uri]] {
    "/proxy.pac" {
       # Retrieve the file contents, send it in a HTTP 200 response    
       HTTP::respond 200 content [ifile get proxy.pac] "Content-Type" "application/x-ns-proxy-autoconfig" "pragma" "no-cache"

    }
default {
            ## requested something else
            HTTP::respond 404 content "Oops! You've asked for something we don't have."
        }   
   }
}