Whonix is a free desktop operating system (OS) that is specifically designed for advanced security and privacy. Based on Tor, Debian GNU/Linux and the principle of security by isolation, it realistically addresses common attack vectors while maintaining usability. Online anonymity is made possible via fail-safe, automatic, and desktop-wide use of the Tor network, meaning all connections are forced through Tor or blocked. The Tor network helps to protect from traffic analysis by bouncing your communications around a distributed network of relays run by global volunteers. Without advanced, end-to-end, netflow correlation attacks, anybody watching your Internet connection cannot easily determine the sites you visit, and those sites cannot learn your physical location. 
- Current practical, low-latency, anonymity designs like Tor fail when the attacker can see both ends of the communication channel (traffic going into and out of the Tor network). If you can see both flows [archive], simple statistics based on data volume and timing can determine whether they match up.