Tor anonymity: how it works and how to use it

The Onion Router (TOR) network is intended to help protect the privacy of Internet users and promote greater freedom of expression online. Tor is a system of volunteer servers that acts as a buffer between Internet users and the resources they connect to. If you connect as a Tor client, your online access is channeled through this buffer before it reaches the general Internet. To understand clearly how Tor functions, you must first have a good idea of what proxy servers are, and of the role they play during network transmissions.

A proxy server acts as a middleman between a client computer and the target server or resource it is accessing. As such, proxies can be configured to log user activity and restrict Internet access; for example, by blocking certain websites or protocols. However, proxies can also help protect the client user’s privacy because the target server is only aware that it is communicating with the proxy, not with the client. For example, if you connect to a web proxy and then load a website, the site is only aware that it is being accessed by the proxy and it has no knowledge of your computer and IP address. The illustration below depicts network data flow when a proxy is deployed. Resources within the Internet icon (such as web servers) are only aware of the proxy server, not of the three clients behind it.

The “Internet” only knows about the proxy, not the three clients

Now what if instead of using a single proxy server, you could connect to a network of them for increased bandwidth and availability? And what if you could encrypt your communication sessions for increased confidentiality? Using Tor, you can.

BitTorrent: How it works and how to use it

BitTorrent is not an application you install; it is a network protocol that facilitates decentralized (or distributed) file sharing over the Internet. In this way it is similar to the functionality provided by traditional peer-to-peer (P2P) applications like Napster in the 1990’s, Kazaa, and Limewire. However, BitTorrent differs fundamentally from these older P2P sharing applications because it introduces components such as BitTorrent websites, torrents, trackers, seeders, and leeches (definitions below).

BitTorrent is also unique in how it efficiently uses bandwidth to achieve high data transfer rates. If the file you want is available from multiple hosts, BitTorrent establishes connections with them and downloads chunks of the file simultaneously. Therefore you trade one large, multimegabyte or multigigabyte download for several individual downloads, each of which is handling a much smaller sized data transfer. Additionally BitTorrent allows you to share these parts of a file even if the file itself isn’t fully downloaded on your end.

Image source: Threestory Studio

Going further, the BitTorrent protocol is designed to ensure that its users share (upload) as much as they take (download). This feature is known as tit-for-tat and is meant to prevent users from downloading without uploading. In fact, BitTorrent tries to reward its generous users like so: the more files you share with others, the faster your downloads are. Obviously the number of users sharing the file you want will also play a role in determining download speed.

Darik’s Boot and Nuke

A situation may arise when you want to completely wipe the data from a hard drive. You may be selling or giving someone your old drive, or perhaps you just want to dispose of one in the trash. Other times your Windows installation could be crawling with malware and you want to completely erase it. Maybe you suspect your drive will soon be forcibly confiscated. In these cases you should obviously be concerned about other individuals accessing your files, even the files that you have “deleted”. For times likes these, Ben Rothke makes the case for secure data destruction in his article ‘Why Information Must Be Destroyed’.

When you want to achieve total data destruction on a drive, a tool like Darik’s Boot and Nuke (DBAN) can save the day. Even though physical destruction is the safest bet, utilities like DBAN are the next best choice. According to Wikipedia, DBAN “is designed to securely erase a hard disk until data is permanently removed and no longer recoverable, which is achieved by overwriting the data with pseudorandom numbers generated by Mersenne twister or ISAAC”.

Version 2.2.7 was released in September 2012. DBAN software is available from SourceForge.

Reset Windows passwords with Offline NT Password & Registry Editor

The Offline NT Password & Registry Editor is a small Linux boot disk that you can use to change or delete Windows passwords outside of the Windows OS environment for local accounts. This can be useful if you forget your Windows password or the password belonging to the Administrator account. This utility can enable you to change or delete passwords, but it cannot tell you what the password for an account actually is. As such it is not appropriate to label Offline NT Password & Registry Editor as a ‘password recovery tool’; it’s a password editor, just like the name says.

It is compatible with Windows 3.x, Windows 95/98/ME, Windows NT, Windows 2000, Windows XP, Windows Server 2003, Windows Vista, Windows 7, and Windows Server 2008.

Please note that the Offline NT Password & Registry Editor (‘Offline’) home page states: “If password is reset on users that have EFS encrypted files, and the system is XP or newer, all encrypted files for that user will be UNREADABLE and cannot be recovered unless you remember the old password again“.

Also note that Offline cannot be used to change or reset Active Directory passwords.

Offline’s versioning is done using release dates. The version used in this tutorial is 110511 (for 11 May 2011).

How to use it

First, download the installation ‘cd******.zip’ file from the website above and extract it locally. Burn the resulting .iso file to a CD-ROM. If you plan to boot to a USB drive, download the ‘usb********.zip’ file and extract its contents to the drive.

Second, insert the CD or USB drive into the computer and reboot it. Before the Windows OS loads (while the manufacturer’s screen is briefly displayed), hit the appropriate key (usually one of the twelve ‘F’ keys) to enter the boot device manager where you can specify a device to boot to (overriding the default device, which is almost always C:\ on the internal hard drive).

Your computer will load the contents of the Offline CD or USB drive. When it is finished you will be prompted as follows.

DigitalVolcano Hash Tool

A hashing algorithm is a one way (non-reversible) function that takes an input (such as a file or message) and produces a fixed-length string of characters (called a hash). This string is not randomly generated; the hashing algorithm looks at the low level arrangement of data bits in the input. Hashing algorithms such as MD5 and SHA-1/SHA-2 verify the integrity of files. If a sender produces a hash of a file and sends the file and hash to a recipient, and the recipient recalculates the hash and gets the same value, both parties can be assured that the file or message was not altered while in transit.

DigitalVolcano’s Hash Tool is a free hash program that you can use to run hashing algorithms on various files.

The DigitalVolcano Hash Tool v1.1 user interface

Google Hacks

Normally when you search for terms on Google, you simply enter those terms and just click ‘search’. There are, however, several ways to tailor the type of results that you get. By using Google search string operators (master list here), you can customize your searches to get more desirable results. Here are some examples.

filetype:type. This option lets you specify which types of files you want results from. Adding filetype:pdf will get you results strictly from PDF files.

intitle. This option lets you specify that you want results only from pages that have matching parameters in their titles. For example, intitle: music will return pages that have the word “music” in their titles.

site. Allows you to search a certain website only, not the whole web. For example, site:wikipedia.org linux will search only Wikipedia.org for the term ‘linux’.

There is a graphical tool that can assist you with such searches. GoogleHacks can save you time and effort with your customized Google searches.

The GoogleHacks v1.6.5 GUI.

To deepen your understanding of Google hacking, have a look at The Google Hacker’s Guide: Understanding and Defending Against the Google Hacker (634 KB PDF) by Johnny Long. Additionally the JimmyR website allows you to perform custom Google searches with an easy to use drop-down menu.

Wget Download Manager

According to the official Wget FAQs, Wget “is a network utility to retrieve files from the World Wide Web using HTTP and FTP, the two most widely used Internet protocols. The program supports recursive retrieval of web-authoring pages as well as FTP sites—you can use Wget to make mirrors of archives and home pages or to travel the Web like a WWW robot, checking for broken links.”

Wget runs on UNIX-like operating systems (such as Linux) and has been ported to Microsoft Windows.

To install on Linux, you should use your package manager application such as Synaptic. Wget for Windows is available here. After it is installed, you run it from a command line (cmd.exe). It does not offer a graphical user interface (GUI).

Wget usage options are presented below and in the official GNU Wget user manual and the Wget Wikipedia page. Some excellent examples of Wget commands can be found in this LifeHacker.com article.