Is it possible to block Tor users?

Question

Would it be possible to block Tor users? (https://www.torproject.org/)

Due to the nature of the site I run I should do all I can to stop multiple accounts and block cert

Answer 1

Detecting Tor traffic is rather easy. The main way to do this is to monitor the Tor exit node list and compare the IP against the list.

I had the need to do such a thing recently and built a small Ruby gem to keep the list of exit nodes up to date and provide a simple way to detect exit nodes. I also wrote a small executable you can use to detect exit nodes.

The gem is open source and can be found here: tor-guard

Installing the gem is simple enough:

$ gem install tor-guard

Using the library in your own Ruby code can be done as follows:

require 'tor-guard'

if TorGuard.exit_node?('108.56.199.13')
    puts "Yep, it's an exit node!"
end

The executable is also easy to use:

$ tg 108.56.199.13 && echo "Yep, it's an exit node"