Exitmap – Tor Exit Relay Scanner

Exitmap is a fast and modular Python-based Tor exit relay scanner. Exitmap modules implement tasks that are run over (a subset of) all exit relays. If you have a background in functional programming, think of exitmap as a map() interface for Tor exit relays.

Modules can perform any TCP-based networking task; fetching a web page, uploading a file, connecting to an SSH server, or joining an IRC channel.

In practice, exitmap is useful to monitor the reliability and trustworthiness of exit relays. Mainly, the team use exitmap to check for false negatives on the Tor Project’s check service and to find malicious exit relays.

Features

Exitmap comes with the following modules:

• testfds: Tests if an exit relay is able to fetch the content of a simple web page. If an exit relay is unable to do that, it might not have enough file descriptors available.
• checktest: Attempts to find false negatives in the Tor Project’s check service.
• dnspoison: Attempts to resolve several domains and compares the received DNS A records to the expected records.
• dnssec: Detects exit relays whose resolver does not validate DNSSEC.
• patchingCheck: Checks for file tampering.
• cloudflared: Checks if a web site returns a CloudFlare CAPTCHA.
• rtt: Measure round-trip times through an exit to various destinations.

Running exitmap

The only argument exitmap requires is the name of a module. For example, you can run exitmap with the checktest module by running:

The command line output will then show you how Tor bootstraps, the output of the checktest module, and a scan summary. If you don’t need three hops and prefer to use two hops with a static first hop, run:

To run the same test over German exit relays only, execute:

If you want to pause for five seconds in between circuit creations to reduce the load on the Tor network and the scanning destination, run:

You can download exitmap here:

exitmap-v2016.04.21.zip

Or read more here.