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# Configuring Hidden Services for Tor

Tor allows clients and servers to offer hidden services. That is, you can offer a web server, SSH server, etc., without revealing your IP to its users. In fact, because you don't use any public address, you can run a hidden service from behind your firewall.

If you have Tor and Privoxy installed, you can see hidden services in action by visiting the hidden wiki.

This howto describes the steps for setting up your own hidden service website.

## Step Zero: Get Tor and Privoxy working

Before you start, you need to make sure 1) Tor is up and running, 2) Privoxy is up and running, 3) Privoxy is configured to point to Tor, and 4) You actually set it up correctly.

Windows users should follow the Windows howto, OS X users should follow the OS X howto, and Linux/BSD/Unix users should follow the Unix howto.

Once you've got Tor and Privoxy installed and configured, you can see hidden services in action by following this link to the hidden wiki. It will typically take 10-60 seconds to load (or to decide that it is currently unreachable). If it fails immediately and your browser pops up an alert saying that "www.6sxoyfb3h2nvok2d.onion could not be found, please check the name and try again" then you haven't configured Tor and Privoxy correctly; see this FAQ entry for some help.

## Step One: Configure an example hidden service

In this step, you're going to configure a hidden service that points to www.google.com. This way we can make sure you have this step working before we start thinking about setting up a web server locally.

First, open your torrc file in your favorite text editor. (See this FAQ entry to learn what this means.) Go to the middle section and look for the line

    ############### This section is just for location-hidden services ###

This section of the file consists of groups of lines, each representing one hidden service. Right now they are all commented out (the lines start with #), so hidden services are disabled. Each group of lines consists of one HiddenServiceDir line, and one or more HiddenServicePort lines:

- HiddenServiceDir is a directory where Tor will store information about that hidden service. In particular, Tor will create a file here named hostname which will tell you the onion URL. You don't need to add any files to this directory.
- HiddenServicePort lets you specify a virtual port (that is, what port people accessing the hidden service will think they're using) and an IP address and port for redirecting connections to this virtual port.

In this example, we're going to set up a hidden service that points to Google. So add the following lines to your torrc:

    HiddenServiceDir /Library/Tor/var/lib/tor/hidden_service/
    HiddenServicePort 80 www.google.com:80

You're going to want to change the HiddenServiceDir line, so it points to an actual directory that is readable/writeable by the user that will be running Tor. The above line should work if you're using the OS X Tor package. On Unix, try "/home/username/hidserv/" and fill in your own username in place of "username". On Windows you might pick:

    HiddenServiceDir C:\Documents and Settings\username\Application Data\hidden_service\
    HiddenServicePort 80 www.google.com:80

Now save the torrc, shut down your Tor, and then start it again. (See this FAQ entry for tips on restarting Tor.)

If Tor starts up again, great. Otherwise, something is wrong. Look at your torrc for obvious mistakes like typos. Then double-check that the directory you picked is writeable by you. If it's still not working, you should look at the Tor logs for hints. (See this FAQ entry if you don't know how to enable or find your log file.)

When Tor starts, it will automatically create the HiddenServiceDir that you specified (if necessary), and it will create two files there. First, it will generate a new public/private keypair for your hidden service, and write it into a file called "private_key". Don't share this key with others -- if you do they will be able to impersonate your hidden service.

The other file it will create is called "hostname". This contains a short summary of your public key -- it will look something like `6sxoyfb3h2nvok2d.onion`. This is the public name for your service, and you can tell it to people, publish it on websites, put it on business cards, etc. (If Tor runs as a different user than you, for example on OS X, Debian, or Red Hat, then you may need to become root to be able to view these files.)

Now that you've restarted Tor, it is busy picking introduction points in the Tor network, and generating what's called a "hidden service descriptor", which is a signed list of introduction points along with the service's full public key. It anonymously publishes this descriptor to the directory servers, and other people anonymously fetch it from the directory servers when they're trying to access your service.

Try it now: paste the contents of the hostname file into your web browser. If it works, you'll get the google frontpage, but the URL in your browser's window will be your hidden service hostname. If it doesn't work, look in your logs for some hints, and keep playing with it until it works.

## Step Two: Now install a web server locally

Now that you have hidden services working on Tor, you need to set up your web server locally. Setting up a web server is tricky, so we're just going to go over a few basics here. If you get stuck or want to do more, find a friend who can help you. We recommend you install a new separate web server for your hidden service, since even if you already have one installed, you may be using it (or want to use it later) for an actual website.

If you're on Unix or OS X and you're comfortable with the command-line, by far the best way to go is to install thttpd. Just grab the latest tarball, untar it (it will create its own directory), and run ./configure && make. Then mkdir hidserv, cd hidserv, and run "../thttpd -p 5222 -h localhost". It will give you back your prompt, and now you're running a webserver on port 5222. You can put files to serve in the hidserv directory.

If you're on Windows, ...what should we suggest here? Is there a good simple free software (not just "freeware") web server for Windows? Please let me know what we should say here. In the meantime, check out apache, and be sure to configure it to bind only to localhost. You should also figure out what port you're listening on, because you'll use it below.

(The reason we bind the web server only to localhost is to make sure it isn't publically accessible. If people could get to it directly, they could confirm that your computer is the one offering the hidden service.)

Once you've got your web server set up, make sure it works: open your browser and go to http://localhost:5222/. Then try putting a file in the main html directory, and make sure it shows up when you access the site.

## Step Three: Connect your web server to your hidden service

This part is very simple. Open up your torrc again, and change the HiddenServicePort line from "www.google.com:80" to "localhost:5222". Then restart Tor. Make sure that it's working by reloading your hidden service hostname in your browser.

## Step Four: More advanced tips

If you plan to keep your service available for a long time, you might want to make a backup copy of the private_key file somewhere.

We avoided recommending Apache above, a) because many people might already be running it for a public web server on their computer, and b) because it's big and has lots of places where it might reveal your IP address or other identifying information, for example in 404 pages. For people who need more functionality, though, Apache may be the right answer. Can somebody make us a checklist of ways to lock down your Apache when you're using it as a hidden service?

If you want to forward multiple virtual ports for a single hidden service, just add more HiddenServicePort lines. If you want to run multiple hidden services from the same Tor client, just add another HiddenServiceDir line. All the following HiddenServicePort lines refer to this HiddenServiceDir line, until you add another HiddenServiceDir line:

    HiddenServiceDir /usr/local/etc/tor/hidden_service/
    HiddenServicePort 80 127.0.0.1:8080

    HiddenServiceDir /usr/local/etc/tor/other_hidden_service/
    HiddenServicePort 6667 127.0.0.1:6667
    HiddenServicePort 22 127.0.0.1:22

There are some anonymity issues you should keep in mind too:

- As mentioned above, be careful of letting your web server reveal identifying information about you, your computer, or your location. For example, readers can probably determine whether it's thttpd or Apache, and learn something about your operating system.
- If your computer isn't online all the time, your hidden service won't be either. This leaks information to an observant adversary.

If you have suggestions for improving this document, please send them to us. Thanks!

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