Tor (short from the English The Onion Router..) - is a system of proxy servers, which allows you to install an anonymous network connection protected from listening. Tor can be called an anonymous network which provides data in encrypted form.
In English the abbreviation «tor» means - Onion Router. If you recall, an onion has many layers, one covering another. Tor also has many "layers", or to be exact -levels of onion-routers. Thanks to them, the system provides anonymous outbound connections and hidden service.
WHO USES TOR AND WHAT CAN IT BE USED FOR?
Users can anonymously visit sites, blog, send messages and use a variety of applications. Tor was created in the Research Laboratory of the Military - US Navy, now the system has powerful financial support from the Ministry of Defense, the US State Department and the National Science Foundation.
This network is used by people around the globe. Each user has their own interests. For example to protect the integrity of their private lives, visit forbidden sites, obtain valuable information from an anonymous source, analyze commercial competitors and many others. Tor is used by security services to conduct covert operations and by social workers to communicate with victims or people with physical or mental disabilities.
THE TOR PRINCIPLE OF OPERATION.
Tor uses a multi-level encryption. Each data packet once in the system, passes through three different proxy server nodes, which are randomly selected and arranged in different parts of the world. Before sending, the packet is encrypted with three keys in sequence: for the third unit, for the second and the first. When the first node receives the packet, it decrypts only the "upper" layer encryption (similar to how you peel an onion) and finds out where to send the packet to.
We have already mentioned that Tor uses multiple nodes, each of which has a different purpose. The input nodes are used for the adoption of a client-initiated network Tor connections, encrypting them and further forwarding to the next node.
Intermediary nodes transmit encrypted traffic only between other Tor networks.
Guard units are selected by the Tor client. One of these nodes is used to access the network for all the chains while these units are in work mode. This means that if the sentinel nodes being used are not controlled by the enemy, then all chains generated by them are also protected.
Bridge nodes - retranslators are nodes of the Tor network, their addresses are not published in the directory server and are used as entry points for the download directory, and for the construction of chains. Since there is no open list of bridges, even blocking all public Tor addresses will not affect the availability of these hidden transponders.
Exit enclaves - are Tor relays that allow you to go to a regular service, located on the same IP-address of the "enclave" itself. This feature is useful for resources that are used through the Tor, in order to prevent the interception of traffic between the output node and service.
THE GOAL OF THE TOR NETWORK.
Runa Sandvik, one of the developers of Tor anonymous network, recently told readers about the purpose of this network: «Tor - this is a safe space for political activists, journalists and other people who potentially may be followed. The Tor is based on the principle - not to hide, but to protect. After all, the user's personal data and what he does online - this is no secret, it's just not for prying eyes. "