Varnish is a web accelerator. Its mission is to sit in front of a web server an cache the content. It makes your web site go fast.
In this mode, Varnish will stop incomplete HTTP requests from reaching your Apache webserver.
Varnish is distributed in the Debian package repositories, but the version there might be out of date, and generally recommend using the packages provided by varnish-cache.org or packages from backports.debian.org.
To use the varnish-cache.org repository and install varnish, do the following:
Change Varnish settings:
1. First change the default port. Edit /etc/default/varnish: