Re: [tor-talk] Layer-7 DoS Attack Against WWW Tor Hidden Service

[bob1983 <bob1983@xxxxxxxxxxxxxx>]

>> Is there a way to limit resource usage originated from a single Tor circuit?

> There is no such functionality right now I'm afraid. People have been
> wanting some sort of functionality like that for a while:
> https://www.hackerfactor.com/blog/index.php?/archives/777-Stopping-Tor-Attacks.html
> but we haven't had time to develop/design something.

The first possible solution quickly came to my mind, was to do what i2p was
doing for years: assigning a placeholder IP address based on the 32-bit hash of
the circuit ID. It is not an ideal countermeasure, but it does work for simple
rate-limiting purpose and compatible with existing IP-based applications and
servers.

I've just checked the source code.

https://github.com/i2p/i2p.i2p/blob/920b14212fa80a3a0e92d6e919fdae7e39ed22d5/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/I2PTunnelServer.java#L739

and it turned out that this feature from i2p was actually based on this patch
purposed in tor-dev mailing list!

[tor-dev] Patch: Hidden service: use inbound bind-address based on circuit ID
https://lists.torproject.org/pipermail/tor-dev/2014-March/006610.html

I don't know if it's still worth to try with this approach, or developing a
separate API should be the right way to go. Any other insights, anyone?

Bob.
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