tor/FAQ

The Onion Routing (TOR) Frequently Asked Questions
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1. General.

1.1. What is tor?

Tor is an implementation of version 2 of Onion Routing.

Onion Routing is a connection-oriented anonymizing communication
service. Users build a layered block of asymmetric encryptions which
describes a source-routed path through a set of nodes. Those nodes
build a "virtual circuit," in which each node knows its predecessor and
successor, but no others. Traffic flowing down the circuit is unwrapped
by a symmetric key at each node which reveals the downstream node.

Basically tor provides a distributed network of servers ('onion
routers'). Users bounce their tcp streams (web traffic, ftp, ssh, etc)
around the routers, and recipients, observers, and even the routers
themselves have difficulty tracking the source of the stream.

1.2. Why's it called tor?

Because tor is the onion routing system. I kept telling people I was
working on onion routing, and they said "Neat. Which one?" Even if onion
routing has become a standard household term, this is the actual onion
routing project, started out of the Naval Research Lab.

(Theories about recursive acronyms are ok too.)


2. Compiling and installing.

[Read the README file for now; check back here once we've got packages/etc
for you.]


3. Running tor.

3.1. What's this about roles? What kind of server should I run?

The same executable ("or") functions as both client and server, depending
on the value of the config variable named 'Role'. Role represents a
combination of which tasks this particular tor server will do. The default
Role (role 15) is an onion router: it listens for onion routers, listens
for onion proxies, listens for application proxies, and it connects to
all other onion routers it learns about. A directory server (role 63)
does all of the above and also serves directory requests. A simple
onion proxy, on the other hand (role 8), only listens for application
proxies. See part 3.1 of the HACKING document for more technical details.

3.2. So I can just run a full onion router and join the network?

No. Users should run just an onion proxy (use the 'oprc' config file).
If you start up a full onion router, the rest of the routers in the
system won't recognize you, so they will reject your handshake attempts.

3.3. How do I join the network then?

If you just want to use the onion routing network, you can run a proxy
and you're all set. If you want to run a router, you must convince
the directory server operators (currently arma@mit.edu) that you're a
trustworthy person. From there, the operators add you to the directory,
which propagates out to the rest of the network. All nodes will know
about you within an hour.

3.4. I want to run a directory server too.

If you run a very reliable node, you plan to be around for a long time,
and you want to spend some time ensuring that router operators are
people we know and like, we may want you to run a directory server
too. We must manually add you to the 'dirservers' file that's part of
the distribution; users will only know about you when they upgrade to
a new version. Of course, you can always just start up your router as a
directory server too --- but users won't know to ask you for directories,
and more importantly, you'll never learn from the real directory servers
about recently joined routers.


4. Development.

4.1. Who's doing this?

4.2. Can I help?

4.3. I've got a bug.


5. Anonymity.

5.1. So I'm totally anonymous if I use tor?

5.2. Where can I learn more about anonymity?


6. Comparison to related projects.

6.1. Onion Routing.

Tor *is* onion routing.

6.2. Freedom.


7. Protocol and application support.

7.1. http? ftp? udp? socks? mozilla?