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Tor (originally acronym of "The Onion Routing") is free software and an open network that helps you defend against a form of network surveillance that threatens personal freedom and privacy, confidential business activities and relationships, and state security known as traffic analysis.

This article explains how to install Tor, and how to use it for anonymous Web browsing as well as how to pipe services to Tor and how to use hidden services.

How does Tor work?

Tor is a connection-oriented anonymizing communication service. Users choose a source-routed path through a set of nodes, and negotiate a "virtual circuit" through the network, in which each node knows its predecessor and successor, but no others. Traffic flowing down the circuit is unwrapped by a symmetric key at each node, which reveals the downstream node.

Basically tor provides a distributed network of servers ("onion routers"). Users bounce their TCP streams (web traffic, ftp, ssh, etc) around the routers, and recipients, observers, and even the routers themselves have difficulty tracking the source of the stream.

Tor security

The big question is "Does Tor really hide what I'm doing?".

The answer will depend on the window you're considering:

  • The first Tor node knows that you're using Tor and sees your IP address
  • The last Tor node doesn't know who you are but, unless your transaction is encrypted (e.g. https), is able of seeing what you're doing.

As a conclusion, and considering the global Tor routing, Tor ensure anonymity but not strict confidentiality.


Two installation modes are available:

  • Tor Browser Bundle: contains everything you need to safely browse the Internet. This package requires no installation and already contains Vidalia, the Tor administration interface. Just extract it and run. This is the recommended installation.
  • Installation from sources