Setting up Proxy .pac files in IIS7 for proxy use

If you want the clients to connect using an automatic configuration script to connect to your proxy server, which will work if it is accessible, and won’t work from else where, e.g. laptop users at home. If the location (http://pac/proxy.pac) can’t be reached, IE will skip over the script and go direct out to the internet.

To setup your proxy .pac file on a Windows Server 2008 server.

1. Create your proxy.pac file (follow the examples below)
2. Copy your .pac file to (C:\inetpub\pac) of your IIS server which will host the .pac file
3. In IIS, right click on sites, choose Add Web Site
4. Fill in the details as below. Under bindings, the host name is what the site will respond to, for example (http://pac/proxy.pac) if you wanted to use a fully qualified DNS name, e.g. http://pac.domain.local/proxy.pac then after you add this site, edit the bindings of the website to add this second binding.
   
   

   

5. Next thing you need to do is edit the MIME types.
6. Add in a custom MIME type for the .pac file extention – application/x-ns-proxy-autoconfig

   

7. You will need to setup a DNS CNAME record so that the hostname pac.domain.local will point to your IIS server.
8. Last thing you will need to do is setup a group policy for all your users to enforce these settings.

Simple PAC file

function FindProxyForURL(url, host)
{
if (isInNet(myIpAddress(), "192.168.1.0", "255.255.255.0"))
return "PROXY 192.168.1.1:8080";
else
return "DIRECT";
}

More complex PAC file

function FindProxyForURL(url, host)
{
if (shExpMatch(url, "http://principia.mo.techpaths.com*")) {
return "DIRECT";
}
if (isInNet(myIpAddress(), "192.168.1.0", "255.255.255.0"))
return "PROXY 192.168.1.1:8080";
else
return "DIRECT";
}

Complex PAC file

function FindProxyForURL(url, host)
{
// variable strings to return
var proxy_yes = "PROXY 192.168.1.1:8080";
var proxy_no = "DIRECT";
if (shExpMatch(url, "http://www.mycompanywebsite.com*")) { return proxy_no; }
if (shExpMatch(url, "http://www.myotherwebsite.com*")) { return proxy_no; }
if (shExpMatch(url, "http://www.my3rdlocalsite.com*")) { return proxy_no; }
// Proxy anything else
return proxy_yes;
}

Very Complex PAC file

function FindProxyForURL(url, host)
{
// variable strings to return
var proxy_yes = "PROXY 192.168.1.1:8080";
var proxy_no = "DIRECT";
if (shExpMatch(url, "http://www.mycompanywebsite.com*")) { return proxy_no; }
if (shExpMatch(url, "http://www.myotherwebsite.com*")) { return proxy_no; }
if (shExpMatch(url, "http://www.my3rdlocalsite.com*")) { return proxy_no; }
if (shExpMatch(url, "http://192.168.1.100*")) { return proxy_no; }
// Proxy if PC is on local LAN
if (isInNet(myIpAddress(), "192.168.1.0", "255.255.255.0"))
return "PROXY 192.168.1.1:8080";
else
return "DIRECT";
}

This is my favorite one

function FindProxyForURL(url, host)
{
// variable strings to return
var proxy_yes = "PROXY 10.3.4.15:8080";
var proxy_no = "DIRECT";
var resolved_ip = dnsResolve(host);

// If a specific URL needs to bypass the proxy then send traffic direct.
if (shExpMatch(url, "*.domain.local*")) { return proxy_no; }
if (shExpMatch(url, "*.dmshm.local*")) { return proxy_no; }
if (shExpMatch(url, "*rms.domain.com.au*")) { return proxy_no; }
if (shExpMatch(url, "*.domain.net.au*")) { return proxy_no; }
if (isInNet(resolved_ip, "10.0.0.0",  "255.0.0.0")) { return proxy_no; }

// If the source IP is in VIC then send traffic via the proxy
if (isInNet(myIpAddress(), "10.3.0.0", "255.255.0.0"))return proxy_yes;

// If the source IP is in NSW then send traffic via the proxy
if (isInNet(myIpAddress(), "10.2.0.0", "255.255.0.0"))return proxy_yes;

// If the proxy fails or the request doesn't meet any of the above criteria then send the traffic direct
elsereturn "DIRECT";
}