Tell .NET application to use default proxy configuration

DefaultNetworkCredentials.cs

WebRequest.DefaultWebProxy.Credentials = CredentialCache.DefaultNetworkCredentials;

DefaultWebProxy.cs

var client = new System.Net.WebClient();
client.Proxy = System.Net.WebRequest.DefaultWebProxy;
client.Proxy.Credentials = System.Net.CredentialCache.DefaultCredentials;
client.DownloadFile(Address, FileName);

proxy.config

<configuration>
  <system.net>
    <defaultProxy useDefaultCredentials="true" />
  </system.net>
</configuration>

proxy.fs

let downloadFile (url:string) targetPath =
    let wc = new Net.WebClient()
    wc.Proxy <- System.Net.WebRequest.DefaultWebProxy;
    wc.Proxy.Credentials <- System.Net.CredentialCache.DefaultCredentials
    wc.DownloadFile(url, targetPath)

proxy.ps1

[System.Net.WebRequest]::DefaultWebProxy.Credentials = [System.Net.CredentialCache]::DefaultNetworkCredentials

# or

$webClient = New-Object System.Net.WebClient
$webClient.Proxy = [System.Net.WebRequest]::DefaultWebProxy;
$webClient.Proxy.Credentials = [System.Net.CredentialCache]::DefaultCredentials;