Tor: Anonymous Browsing

INTRODUCTION

Source: torproject.org

Anonymous browsing is meant for anyone who wants of hide his online trails. An individual may be a journalist, an activist, military, a whistle blower, an employee behind the company firewall-stopping the global access or law enforcing agency. Prime idea of anonymity is to circumvent censorship and to protect privacy.  A mere installation of tor may prove to be a sufficient evidence of crime in some places. One must be very careful regarding the state laws and the uses of anonymous browsing.

 
A THREAD OF TRUST

 
When we are using a particular software, it implies that we trust the author of the program. If we don't know the author personally, in that case, we count on his public reputation. Tor is an open source project. It means that the source code is free for distribution and open to review to ensure that no backdoor has been planted in the program. It is a good idea to know who are the people behind Tor and supporting Tor project.

WORKING OF TOR

 
Tor uses layers of encryption to hide the content and it recommends https everywhere.
The use of https encrypts the entire content of the data packet except for the headers.
Three parts of TOR Network are
1.    Entry Node
2.    Transit Node
3.    Exit Node

A tor user uses the entry node to enter into the tor network. The exit node of the tor network connects to the public internet. The public website logs will only reflect the details of the exit node and no details of the tor user at all. In between the Entry node and exit node are a pair of transient nodes. At each hop from the entry to transient node, the data traffic is encrypted at each hop. However the connection from the tor user to the entry node and the connection from the exit node to the public website is not encrypted and may serve as a point of attack by any adversary with intention to track a tor user's activity online. Such kind of attacks are called end to end timing attacks.

Tor traffic will be very slow at  times because of extra overheads of encryption added at each hop. There are servers which act as the entry node or exit node, but a client can also provide such services to the community. Tor is a peer to peer network. As a part of tor network, an individual may serve as transit node for tor users.

ONION ROUTING PROTOCOL

Tor follows Onion routing protocol. In simple words, it means that the traffic is wrapped in several layers and it gets unfolded as it is sent and received.

A user can choose either of two methods to use anonymous browsing:
1.    Tor Browser Bundle(TBB)
2.    Tails OS

TBB(Tor Browser Bundle) is maintained by Vidalia Control Panel. It comes in-built with a browser of Mozilla software foundation. Once it is installed in an OS, it is ready to go.

TAILS
 

TAILS stands for Amnesic Incognito Live System. It is a sub part of the tor project. It is a complete OS but it is advised not to use PII(Personally Identifiable Information) over tor as one can get tracked down. Once a file has been downloaded over tor, it may contain certain link which may establish the connection with the original source when the file is opened. Under such cases, an association of the tor exit relay and the real public IP of the user may be formed by the adversary. So it is advised to open such files over tor session only. Under such use case scenario, TAILS is advantageous over TBB being used over Windows or OSX.

Certain software package pre-installed in TAILS:

 
1.    Firefox Iceweasel Browser
2.    GPG(Gnu Privacy Guard)
3.    OpenOffice
4.    Metadata Anonymization Toolkit(MAT)

RECOMMENDATIONS ON USE OF TOR
It is highly recommended to use the latest version of TAILS OS as the security of an outdated version might have been compromised. One can't take chances on the issue of privacy and security that too when it is free of cost. It is important to verify the hash value of the downloaded file with the one being shown on the public
Use new identity is a feature with which the tor circuit changes. It is advisible to use this if browsing to the same destination regularly. Ex. Updating Blogs.

RISKS INVOLVED WITH TOR
1.    Abuse complaint(while acting as exit relay)
2.    Bandwidth
3.    ISP's restriction on Tor Traffic