Tor is a free software program that allows users to communicate anonymously. The name, Tor is an acronym that has been derived from the original name of the software project, which was The Onion Router. This software directs all Internet traffic and usage through a free volunteer network that exists worldwide, and has over six thousand relays to hide ip and location of the user; and hide Internet usage from individuals and authorities that are in charge of carrying out traffic analysis or network surveillance.

If an individual is using Tor, it becomes fairly difficult to track his or her Internet activity. By using Tor, one's usage is completely concealed including online posts, the type of websites that have been visited, and any instant messages that have been exchanged.

The purpose of using Tor is to provide individuals with privacy protection and anonymity. Tor allows you to bounce your communication around a distributed network and prevents anyone to monitor your browsing activity. Tor is not an encryption software, so you should still keep your confidential information confidential unless you're communicating via https or vpn. There are some parties and individuals who can gain from monitoring individuals' Internet activities. Political activists, for example, who may be living in fear of surveillance or arrests are much more at ease with the use of Tor. People living in a communist country may also use Tor to avoid censorship rules and regulations that may have been imposed by a governing agency. In addition to this, it also offers protection to those individuals who were previously threatened and abused by stalkers or Cyberbullying.

Due to the highly anonymous nature of Tor, it is also used for various illegal purposes. For example, people may try to use Tor in order to gain access to secretive or censored information. It may also be used to rally political support against the governing political body. Furthermore, it may also be used to circumvent laws and regulations against the criticism of the heads of state.

Tor works mainly through multi-layered encryption, which is why the onion metaphor is used. This ensures the right kind of forward secrecy between all the relays, which provides the required privacy and anonymity to the users.

What are some weaknesses of Tor?

This software program does not protect the monitoring of Internet traffic at the Tor network boundaries, which is where all the traffic enters and exits the network. Similarly, it does not prevent traffic confirmation although it does help in providing protection from the traffic analysis.

Those using Tor can expect to see autonomous system eavesdropping. This happens when there is an autonomous system on both the path segments, that is, from the client to the entry relay, as well as from the exit relay to the destination. This can correlate the traffic on both the exit and entry segments of this path, which means that, potentially, the destination to which the client tried to communicate with may be inferred.

Similarly, exit node eavesdropping can also take place. This is because the software does not encrypt any traffic that passes between the target server and the exit node and the exit node is thus capable of capturing the traffic that passes through it and does not make use of end-to-end encryption, like the Transport Layer Security (TLS) or the Secure Sockets Layer (SSL). This means that there is a possibility of traffic being breached. However, any traffic that is intercepted by self-selected third parties does have the power to expose any information of the source in the payload or protocol data, or both. Those using Tor may also be susceptible to the traffic-analysis attack. However, even then, the original user's identity is not going to be revealed.

Other weaknesses include the Tor exit node block and the bad Apple attack. Internet site operations can prevent any traffic received through Tor exit nodes. They can also opt to offer less functionality to users of this software. For example, people using Tor will probably not be able to edit any Wikipedia pages, since MediaWiki uses a TorBlock extension. Similarly, the BBC website also blocks the IP addresses of Tor relays. The bad apple attack is used to refer to the exposure of IP addresses of users of BitTorrent using Tor. This attack takes advantage of the design of the software and exploits insecure application use, which allows it to associate the use of the secure application with the Tor user's IP address. One method of this bad apple attack relies mainly on the control of the exit node or hijacking the tracker responses, whereas another method is based on statistically exploiting distributed hash table tracking.

Additional weaknesses are the Heartbleed bug and the sniper attack, which uses a colluding server and client and fills in the exit node queues until the memory finishes, which means that this node is no longer capable of serving other clients.

Why should you use a VPN instead?

Tor is free software available to protect their identity and anonymity without denting their wallet. Free is good but there are a few drawbacks to using Tor including slow performance and some blockage from known networks. If you're solely using Tor to browse static websites, Tor may be a good solution for protecting your anonymity but it may become painful to use on other applications such as downloading Torrents or watching HD videos.

An alternative to using Tor is VPN. Personal VPN provides an encrypted tunnel of the private channel to communicate with the rest of the Internet and provides all benefits offered by Tor and more.