I run a very small non-profit website and sometimes there are people that attack the website for unknown reasons to me, I use a dedicated server but the TOR Process itself uses only one core when attack occurs, that means, there is X cores left free which are being unused and I assume could handle the TOR load.

I read somewhere that Tor is Single cored process? Is it true? Is there something I can do about it? As I said it's nonprofit and I make only few $ a month if I consider donations. It's not worth it for me to build a huge clusters. Any ideas?

I've also noticed that my tor version is v0.2.5.16 which I can't update anymore, I assume it's because I use older distro.

Thanks in advance for all tips/posts/replies and your time.


First, I highly recommend upgrading your Tor version as it no longer receives bug fixes or security patches (or new v3 onion addresses). If you're running Debian or Ubuntu, you can check if your version is supported here: https://2019.www.torproject.org/docs/debian.html.en

As for your high CPU usage, tor is mostly single-threaded, so the behavior you see is expected. You may be interested in trying OnionBalance, which allows you to scale the load on your hidden service across multiple tor processes (and multiple computers). This will not prevent all types of DoS attacks, but may help in your case.

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