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

It is possible due to the tor project publishing a list of exit proxies.

The list of exit proxies can be downloaded directly from the project at https://check.torproject.org/exit-addresses in space delimited text form.

I have written a python script to add iptables rules for all exit nodes that reject all packets from them. You can find the script on github here: https://github.com/vab/torblock

If the Tor Project ever decides to stop publishing a list of exit nodes it will be possible to block them. Code would just need to be written to connect to the tor network and discover the exit nodes.