ASP.Net IIS web application send all requests via proxy without code change

For your web application, edit the web.config file (in the app root) and add as shown below. Note: you may already have a system.net or configuration section. You will have to add the defaultproxy section to the existing parent elements as needed

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.net>
    <defaultProxy enabled="true" useDefaultCredentials="true">
      <proxy proxyaddress="http://proxyservername:proxyserverport/" bypassonlocal="false" usesystemdefault="false" autoDetect="false" />
    </defaultProxy>
  </system.net>
</configuration>

Setting a proxy for a standalone Microsoft .Net application

1. Find the applications install location (or .exe location). If you are using a shortcut, you can right click, and check the properties to find this place.
2. Locate your applications .config file. Typically this will be in the same folder as your .exe; For example, for myappname.exe, you should be able to see myappname.exe.config in the same directory
3. Create one if there there is only not already present. Make sure to name it myappname.exe.config
4. If creating a new file, Open the newly created file in notepad, and paste the below into it. Make sure to change proxyservername & proxyserverport in your environment
5. if file already exists, add the defaultProxy section as shown below and save file
6. Restart the application

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.net>
    <defaultProxy enabled="true" useDefaultCredentials="true">
      <proxy proxyaddress="http://proxyservername:proxyserverport/" bypassonlocal="false" usesystemdefault="false" autoDetect="false" />
    </defaultProxy>
  </system.net>
</configuration>