# Tor documentation

Tor provides a distributed network of servers ("onion routers"). Users bounce their communications (web requests, IM, IRC, SSH, etc.) around the routers. This makes it hard for recipients, observers, and even the onion routers themselves to track the source of the stream.

## Why should I use Tor?

Individuals need Tor for privacy:

- Privacy in web browsing -- both from the remote website (so it can't track and sell your behavior), and similarly from your local ISP.
- Safety in web browsing: if your local government doesn't approve of its citizens visiting certain websites, they may monitor the sites and put readers on a list of suspicious persons.
- Circumvention of local censorship: connect to resources (news sites, instant messaging, etc.) that are restricted from your ISP/school/company/government.
- Socially sensitive communication: chat rooms and web forums for rape and abuse survivors, or people with illnesses.

Journalists and NGOs need Tor for safety:

- Allowing dissidents and whistleblowers to communicate more safely.
- Censorship-resistant publication, such as making available your home-made movie anonymously via a Tor hidden service; and reading, e.g. of news sites not permitted in some countries.
- Allowing your workers to check back with your home website while they're in a foreign country, without notifying everybody nearby that they're working with your organization.

Companies need Tor for business security:

- Competitive analysis: browse the competition's website safely.
- Protecting collaborations of sensitive business units or partners.
- Protecting procurement suppliers or patterns.
- Putting the "P" back in "VPN": traditional VPNs reveal the exact amount and frequency of communication. Which locations have employees working late? Which locations have employees consulting job-hunting websites? Which research groups are communicating with your company's patent lawyers?

Governments need Tor for traffic-analysis-resistant communication:

- Open source intelligence gathering (hiding individual analysts is not enough -- the organization itself may be sensitive).
- Defense in depth on open and classified networks -- networks with a million users (even if they're all cleared) can't be made safe just by hardening them to external threat.
- Dynamic and semi-trusted international coalitions: the network can be shared without revealing the existence or amount of communication between all parties.
- Networks partially under known hostile control: to block communications, the enemy must take down the whole network.
- Politically sensitive negotiations.
- Road warriors.
- Protecting procurement patterns.
- Anonymous tips.

Law enforcement needs Tor for safety:

- Allowing anonymous tips or crime reporting
- Allowing agents to observe websites without notifying them that they're being observed (or, more broadly, without having it be an official visit from law enforcement).
- Surveillance and honeypots (sting operations)

Does the idea of sharing the Tor network with all of these groups bother you? It shouldn't -- you need them for your security.

## Installing and configuring Tor

See the Windows, OS X, and Linux/BSD/Unix documentation guides.

## Configuring a server

We've moved this section over to the new Tor Server Configuration Guide. Hope you like it.

## Configuring a hidden service

We've moved this section over to the new Tor Hidden Service Howto. Hope you like it.

## Setting up your own network

If you want to experiment locally with your own network, or you're cut off from the Internet and want to be able to mess with Tor still, then you may want to set up your own separate Tor network.

To set up your own Tor network, you need to run your own directory servers, and you need to configure each client and server so it knows about your directory servers rather than the default ones.

- 1: Grab the latest release. Use at least 0.0.9.5.
- 2: For each directory server you want,
  - 2a: Set it up as a server (see "setting up a server" above), with a least ORPort, DirPort, DataDirectory, and Nickname defined. Set "AuthoritativeDirectory 1".
  - 2b: Set "RecommendedVersions" to a comma-separated list of acceptable versions of the code for clients and servers to be running.
  - 2c: Run it: `tor --list-fingerprint` if your torrc is in the default place, or `tor -f torrc --list-fingerprint` to specify one. This will generate your keys and output a fingerprint line.
- 3: Now you need to teach clients and servers to use the new dirservers. For each fingerprint, add a line like
  `DirServer 18.244.0.114:80 719B E45D E224 B607 C537 07D0 E214 3E2D 423E 74CF`
  to the torrc of each client and server who will be using your network.
- 4: Create a file called approved-routers in the DataDirectory of each directory server. Collect the 'fingerprint' lines from each server (including directory servers), and include them (one per line) in each approved-routers file. You can hup the tor process for each directory server to reload the approved-routers file (so you don't have to restart the process).