HTTP Injector is an app for professional use that's designed to set a custom HTTP header. Plus you can access sites blocked behind a firewall using SSH tunneling. And all that with no need for root.
Using HTTP Injector can be a bit complicated, but its official webpage has a very handy manual to help you out. Plus you can import the configurations created by other users, and it takes just a few seconds to do so.
Within HTTP Injector there's also a wide array of different tools. The IP Hunter, for example, lets you look for local IPs, while the diagnostic tool gives you the chance to check that everything is running properly on your device.
