How can I know if the website I am accessing is behind a reverse proxy?

Question

A reverse proxy hides the existence of the origin server. How can I therefore tell if a web site is behind a reverse proxy?

If I ping a website located behind a reverse proxy I will get the IP of the reverse proxy server and not of the server hosting that website, right?

Answer 1

You may try examining the HTTP headers of responses from the server to see if there are any clues. Standard proxies (like squid) can be configured to insert a Via: line or similar in the headers. Most likely a reverse proxy isn't going to do this or is going to be configured not to do this, but it is worth a shot.

Pinging a web server acting as a reverse proxy will reveal the IP of the "front end" server and NOT the server behind the reverse proxy. ICMP does not travel over or have anything to do with HTTP so there is no way this could happen.