C# auto detect proxy settings

Question

C# 2008 SP1

I am using the code to detect if a proxy has been set under \"Internet Options\". If there is a proxy then I will set this in my webclient.

So I

Answer 1

Check out the System.Net.Configuration.ProxyElement class. That may have info you're looking for.

What you describe works, you can also look in the registry.

Here's a powershell script I wrote to check out the proxy:

function get-proxy
{
    $path = "HKCU:\Software\Microsoft\Windows\CurrentVersion\Internet Settings"
    $reg = get-itemproperty $path
    return $reg
}

Answer 2

<system.net>
<defaultProxy enabled="false" useDefaultCredentials="false">
  <proxy/>
  <bypasslist/>
  <module/>
</defaultProxy>

Use this snippet in application.config file.

Answer 3

First, GetDefaultProxy is marked as deprecated so you have no guarantee it will be around in even the immediate future. Second, Address can be null so the code you gave risks a NullReferenceException:

Answer 4

It appears that WebRequest.DefaultWebProxy is the official replacement for WebProxy.GetDefaultProxy.

You should be able to drop that in to your original code with only a little modification. Something like:

WebProxy proxy = (WebProxy) WebRequest.DefaultWebProxy;
if (proxy.Address.AbsoluteUri != string.Empty)
{
    Console.WriteLine("Proxy URL: " + proxy.Address.AbsoluteUri);
    wc.Proxy = proxy;
}

Answer 5

Setting my request proxy to WebRequest.GetSystemWebProxy() solved the problem.

WebProxy.GetDefaultProxy() is the actual way but it is now deprecated.

Answer 6

WebClient etc use the WinHTTP settings (not the IE settings), so the easiest thing to do is to configure WinHTTP! On XP etc you can use:

proxycfg -u

to import the current IE settings into the WinHTTP store. After that, WebClient etc should be able to use the same settings without issue. On Vista and Windows 7 this is now found under:

netsh winhttp import proxy ie

You need to run this as administrator.