C# Connecting Through Proxy

Question

I work in a office which requires all connections to be made through a specific http proxy. I need to write a simple application to query some values from a webserver - it's easy if there were no proxy. How can I make the C# application proxy-aware? How can I make any sort of connection through a proxy?

Answer 1

This is easily achieved either programmatically, in your code, or declaratively in either the web.config or the app.config.

You can programmatically create a proxy like so:

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("[ultimate destination of your request]"); WebProxy myproxy = new WebProxy("[your proxy address]", [your proxy port number]); myproxy.BypassProxyOnLocal = false; request.Proxy = myproxy; request.Method = "GET"; HttpWebResponse response = (HttpWebResponse) request.GetResponse(); 

You're basically assigning the WebProxy object to the request object's proxy property. This request will then use the proxy you define.

To achieve the same thing declaratively, you can do the following:

<system.net>   <defaultProxy>     <proxy       proxyaddress="http://[your proxy address and port number]"       bypassonlocal="false"     />   </defaultProxy> </system.net> 

within your web.config or app.config. This sets a default proxy that all http requests will use. Depending upon exactly what you need to achieve, you may or may not require some of the additional attributes of the defaultProxy / proxy element, so please refer to the documentation for those.

Answer 2

If you are using WebClient, it has a Proxy property you can use.

As other have mentioned, there are several ways to automate proxy setting detection/usage

Web.Config:

<system.net>    <defaultProxy enabled="true" useDefaultCredentials="true">      <proxy usesystemdefault="true" bypassonlocal="true" />    </defaultProxy> </system.net> 

Use of the WebProxy class as described in this article.

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You can also cofigure the proxy settings directly (config or code) and your app will then use those.

Web.Config:

<system.net>   <defaultProxy>     <proxy       proxyaddress="http://[proxy address]:[proxy port]"       bypassonlocal="false"     />   </defaultProxy> </system.net> 

Code:

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("url"); WebProxy myproxy = new WebProxy("[proxy address]:[proxy port]", false); request.Proxy = myproxy; request.Method = "GET"; HttpWebResponse response = (HttpWebResponse) request.GetResponse();