Re: [squid-users] proxy.pac

I think it's important to note that WPAD (Proxy Autodiscovery) is a hosed
implementation in Internet Explorer.
You'll notice that few other browsers even have the functionality.

WPAD, ("Automatically Detect Settings" check box in IE) was established to
either set a DNS entry for wpad.domain.com to point to the proxy server,
or for DHCP to assign a proxy server automatically.
The short answer is that IE's implementation is flakey as they've
essentially ignored RFC suggestions. I've been told that WPAD works
flawlessly in IE, so long as your DNS/DHCP server is running on a
Microsoft Windows Server.

It's also important to note that the IETF has discontinued efforts to
standardize WPAD. They did so several years ago.
I hope you weren't planning on using WPAD. My recommendation is to use an
autoconfiguration script, then point your clients directly to the script.

Proxy Auto Config scripts are really quite simple. Using some simple
javascript functions, the script can be easily set up to do what you want
to do.
The pac (we call ours wpad.dat) sits in the root of the web server,
running on the proxy server. The clients are then pointed to the script,
via the following script setting in their browser:
http://proxyserver/proxy.pac

Our script reads as follows (explanation is below the script. Take out
the line numbers, if you plan to copy/paste the code)

1 function FindProxyForURL(url, host)
   {
2 if (isPlainHostName(host) || isInNet(host, "172.24.0.0",
"255.255.0.0")
3 ||
isInNet(host, "172.16.0.0", "255.255.0.0")
4 ||
isInNet(host, "192.168.0.0", "255.255.0.0"))
5 return "DIRECT";
6 else
7 return "PROXY wpad.kal.kalsec.com:8000; PROXY
wpad.kal.kalsec.com:8080; DIRECT";
}

1.) Required. This function tells the proxy server that it needs to
process the script's credentials, in order to find the appropriate proxy
server.
2-5.) This function checks the URL being requested to see if it exists on
any of our local networks here. If it does, the browser is directed to
the web page directly, without going through the proxy. We did this
because we
          didn't want the proxy server to bother with processing requests
made to local services on our network.
6.) If the URL being requested does not exist on our network...
7.) First try port 8000 on our proxy server (wpad.kal.kalsec.com). If
that request is not fulfilled, try port 8080 on our proxy server. If that
request is not fulfilled, access the site directly.

Netscape has put together a great tutorial for writing proxy autoconfig
scripts and also explains several different advantages and methods to
using them.
The tutorial is at =>
http://wp.netscape.com/eng/mozilla/2.0/relnotes/demo/proxy-live.html

Good luck.

Tim Rainier

dharam paul <exiaf_radar_guy38@yahoo.co.in> wrote on 04/18/2006 09:10:01
AM:

> Hi,
> Here is a newbie not very technical trying to
> implement a proxy pac system where if the proxy dies
> the Browser connects directly to the internet.
> Help on this is requested please.
> Regards
>
>
>
> __________________________________________________________
> Yahoo! India Matrimony: Find your partner now. Go to
http://yahoo.shaadi.com
Received on Tue Apr 18 2006 - 07:25:31 MDT