How to get client's IP number to Drupal when using Varnish
There are a lot of places, where you need client's IP address in Drupal (or any other CMS/web app of course). The problem arises, when you use a reverse proxy server (like Varnish), since every request to web server will be done by the latter. We will have every single visitor of our website coming from a single IP (reverse proxy), as a result.