The onion router (tor)

Tor stands for the onion router

Tor stands for the onion router and is free of charge software that is one of the best anonymity (obscurity), privacy and unblocking tools existing on the internet. Tor has thousands of volunteer relay servers in different parts of the world through which a user’s data is routed and completely anonymous. Not only does it defend your freedom on the internet by allowing you to access all your favorite websites on the internet, it keeps all your communications in the internet completely secure. It can be downloaded free off cost from https://www.torproject.org.

A number of organizations and governments like to monitor the internet by performing something known as traffic analysis. For example, imagine your company could be running a data sniffer on the company network to look at the traffic on the network to a bigger level, the government could be running a data sniffer on all the major ISPs networks with the intention to record, check and examine traffic of all users in a country. This information could then be used to block access to certain websites as well.

Typically, all data is being transmitted on the internet in the form of data packets. Each data packet has two parts:

DATA: this is the real data that is being transmitted in the data packet. It could be a part of email, file or webpage.

HEADER: this contains important information about the source and target computers that is used to route the data through the internet.

There are a lot of ways wherein the data being transmitted on the internet can be encrypted. For example, it is possible to encrypt an email via PGP encryption and then send it out on the internet. However, encrypting the actual data does not hide the header of a data packet. This means that somebody who is using a data sniffer at your ISP or company or college network could still easily read the header part of the data transfer and figure out valuable information about the source and destination of the data packets. Such intermediaries that could be monitoring and spying on your data communication like your college, company, ISP or even the government. In other words, imagine that you want to communicate with your bank, and then typically something like the following communication route is established:

Your computer-company or college network –ISP network- ISP backbone-bank’s ISP-bank

Obviously, in a communication like the above, your compute ran your bank will know everything about both the data and the data header. But based on how internet routing work, all intermediaries along the way (like your company/college, ISP, ISP backbone, bank’s ISP and others) could be spying upon the data header and even the data (if it is not encrypted) using a simple data sniffer. This means that the source and destination computers have no anonymity on the internet. All intermediaries knew who the source and the destination are.

One of my favorite data sniffers is free software called wire shark (http://www.wireshark.org/) that allows criminal and received across the entire network. Even if a user has encrypted the actual data being sent on the internet, wire shark can be used to record and analyze the header information of figure out valuable details about the source and destination involved in the data transfer.

This is where onion routing comes into the picture. It is an anonymous communication mechanism that ensures that the intermediaries can read neither the data nor the data header that they are transmitting, hence giving complete anonymity to both the sender and the destination systems.

Tor is fantastic free utility that uses onion routing to provide users with a secure, anonymous and encrypted communication channel for all their data transfer needs. Once installed, all applications on your computer can be configured to communicate on the internet through the tor relay servers (onion routers) in (http://www.torproject.org); tor works in the following steps:

Step 1:

Let us assume that you want to connect to www.domain.com through an encrypted communication channel that is completely secure and anonymous at the same time. You need to install tor on; your computer and make sure that you have configured your browser to connect the internet through tor. (We will see how to do that later5 on in this book.) once tor receive your request to connect to www.domain.com, it will first connect to the tor directory server and download a list of all available tor relay nodes(onion routers) that it can potentially connect to.

Step 2:

Tor will now create a secure encrypted connection between you and www.domain.com by routing the connection through any three randomly selected tor relay nodes (onion routers) circuit. Tor will make use of onion routing principals while establishing this encrypted secure tor circuit. Tor relay routers in any part of the world before connection the user to the destination system, hence ensuring adequately randomized anonymity. The advantage of tor over a proxy server is that tor ensures that you are always routed via a minimum of three different tor relay server. On the other hand; in case of a proxy server, you are normally routed only though one system.

Step 3:

Once a tor circuit has been created, it will continue to be used for all connections for 10 minutes or so, after which all new connections will be given completely new tor circuits. It is minutes if required. Whenever tor changes its circuits, your identity on the internet also changes.

Now that we have understood how tor circuits are. It is also possible to force tor to change its circuit sooner than 10minutes if required. Whenever tor change it circuit, your identity on the internet also changes.

Now that we have understood how tor circuits are established and how tor works, let us now put this knowledge to use and actually use it to anonymously and safely unblock a blocked website on the internet.

STEP 1:

Download the free tor browser

https://www.torproject.org.

The tor browser bundle is a self-contained executable file that can be run directly from a USB pen drive or even a camera SD card without the need for any installation or configuration. It comes with a copy of the Firefox portable browser preconfigured and allows users to establish a secure encrypted connection easily and quickly without any hassle of configuration.

STEP 2:

After downloading the tor browser bundle, you need to extract it to a folder of your choice. It could be anywhere on your hard drive or even on an external USB pen drive. To launch tor, you just need to go to the respective folder and double chick on the start tor browser icon.

STEP 3:

As soon as you double click on the start tor browser icon, the Vidalia control panel will open. At this stage, tor will connect to its directory server and download a list of available tor relay servers( onion routers) and then try to establish a secure encrypted tor circuit through any three different randomly selected should not take more than a few seconds. As soon as a secure tor circuit has been established, a new Mozilla Firefox browser window will automatically open.

Once Mozilla Firefox launches, it means that the secure tor circuit has need established and you can start browsing the internet securely and anonymously. The Firefox Mozilla window that opens will also say congratulations. Your browser is configured to use tor, letting you known that tor is now ready to be used.