Overview

Sybilhunter is a command line tool written in Go to discover and analyse Sybil relays in the Tor network. It does so by implementing a number of analysis techniques that take as input archived Tor network data. For example, sybilhunter can tell you (i) when an unusally large amount of relays joined or left the Tor network, (ii) which Tor relays changed their identity keys a lot, and (iii) which Tor relays are configured very similar to each other. Ideally, sybilhunter should become a Swiss Army knife for analysing anomalies in network consensuses and relay descriptors. The theory behind sybilhunter is discussed in a research paper that was published at the USENIX Security 2016 conference.

Get started in 5 minutes

Assuming you have a working Go installation, this is how you can get started:

$ go get github.com/NullHypothesis/sybilhunter
$ wget https://collector.torproject.org/archive/relay-descriptors/consensuses/consensuses-2015-08.tar.xz
$ tar xvJf consensuses-2015-08.tar.xz
$ sybilhunter -data consensuses-2015-08 -print

Now you have one month worth of consensuses and can proceed to the next section to learn more about analysis examples.

Examples

Sybilhunter takes as input data obtained from CollecTor. Let's start by pretty-printing a file containing a network consensus or relay descriptors:

$ sybilhunter -data /path/to/file -print

Next, here's how you can analyse how often relays changed their fingerprint in a set of consensus documents:

$ sybilhunter -data /path/to/consensuses/ -fingerprints

Sybilhunter is also able to create uptime images, visualising the uptime of relays over time. In such an image, every column is a relay and every row is a consensus. Each pixel is either black (relay was offline) or white (relay was online). Red blocks are adjacent relays with identical uptime. You can create an uptime image by running:

$ sybilhunter -data /path/to/consensuses/ -uptime

Sybilhunter then writes an image like the following to disk:

You can also put command line arguments into the configuration file ~/.sybilhunterrc. The format is just like command line arguments, one per line. For example:

$ cat ~/.sybilhunterrc
-descdir /path/to/server/descriptors/
-referencerelay 9B94CD0B7B8057EAF21BA7F023B7A1C8CA9CE645

Note that command line arguments overwrite the arguments in the configuration file.

Alternatives

Check out doctor's sybil checker script, and hstools can be useful for finding anomalies in hidden service directories.

Contact

For bugs and requests, please file a ticket in The Tor Project's bug tracker. You can also contact me privately:

Contact: Philipp Winter [email protected]
OpenPGP fingerprint: B369 E7A2 18FE CEAD EB96 8C73 CF70 89E3 D7FD C0D0