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When Internet Explorer is set to auto-detect proxy settings, is there a way to view what it detects?

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@ymasood that's what the little ^ arrow is for –  Aidan Ryan Sep 1 '09 at 12:33
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up vote 18 down vote accepted

The settings are retrieved from http://wpad/wpad.dat which is a javascript file describing which proxy server should be used in which situation. Your best bet is to open that URL and figure the proxy out from the contents it returns.

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Ah, excellent. Here is more detail on the Web Proxy AutoDiscovery protocol: en.wikipedia.org/wiki/Web_Proxy_Autodiscovery_Protocol –  Aidan Ryan Sep 1 '09 at 23:22
    
Are you sure that's the link? What's wpad's top level domain? –  Nathan Fellman Oct 10 '09 at 8:38
    
Oh... I see. I should use wpad in my local domain –  Nathan Fellman Oct 11 '09 at 6:20
    
This doesn't work for all networks. Sometimes proxy is autodetected over dhcp (inform verb) rather than http wpad. –  Colonel Panic Jul 1 '13 at 12:58
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If http://wpad/wpad.dat is not available, you can deduce which proxies are in use by browsing to a web site and then checking the TCP connection that was made. It's not great, but it's at least minimally useful.

  1. Inspect the output of netstat -an | find "EST" (short for 'ESTABLISHED').
  2. Go to a fresh site (one that you have not recently visited).
  3. Run the netstat command again, looking for the new connection. It might look like:

    TCP 192.168.1.1:1989 192.168.1.88:8080 ESTABLISHED

In this example, your proxy's IP is 192.168.1.88 and it is listening on port 8080.

Note that this method only shows the proxy currently in use. If more than one proxy is configured in your environment, and you want to know all of them, you'd have to repeat the procedure above periodically to get the full list.

The same procedure can be used on non-Windows boxes (using netstat -an | grep EST, or whatever your OS uses to show active connections).

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Nice workaround :) –  hoang Jun 10 '13 at 13:23
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