.NET Configuration file - proxy settings

readme.txt

.NET Documentation
https://docs.microsoft.com/en-us/dotnet/framework/configure-apps/file-schema/network/proxy-element-network-settings

bypassonlocal     Specifies whether the proxy is bypassed for local resources. Local resources include the local server (http://localhost, http://loopback, or http://127.0.0.1) and a URI without a period (http://webserver). The default value is unspecified.
proxyaddress      Specifies the proxy URI to use.
usesystemdefault  Specifies whether to use Internet Explorer proxy settings. If set to true, subsequent attributes will override Internet Explorer proxy settings. The default value is unspecified.

app.config

<?xml version="1.0"?>
<configuration>
	<configSections>
		<!-- config sections -->
	</configSections>
	<system.net>
		<defaultProxy enabled="true">
			<proxy usesystemdefault="true"  proxyaddress="http://127.0.0.1:8888"  bypassonlocal="false"  />
		</defaultProxy>
	</system.net>
</configuration>