http://y7egb5vi45k74makeixpfb7jnimfxm3gf233lb3ke2ldonozjk55nvad.onion/nginx_hacking.html
Raw backend response reading With Nginx’s proxy_pass, there’s the possibility to intercept errors
and HTTP headers created by the backend. This is very useful if you want
to hide internal error messages and headers so they are instead handled
by Nginx. Nginx will automatically serve a custom error page if the
backend answers with one.