[tor-dev] Pluggable Transports and rate limiting

Andreas Krey a.krey at gmx.de
Tue Sep 10 11:36:16 UTC 2013

On Tue, 10 Sep 2013 14:17:12 +0000, George Kadianakis wrote:
> Hey Yawning (and tor-dev),
> a topic that we will soon need to consider seriously is rate limiting
> of pluggable transports. For example, Obfsproxy at the moment does not
> understand rate limiting and will happily read and write as many bytes
> as needed.

My first reaction: Why should it care? As long as it only reads from
the input as long as the output isn't/wouldn't be blocking, all
is fine with the transport - it behaves like the direct TCP bridge

> For example, I'm kind of sad about this approach, because it requires
> little-t-tor to do all the hard work of monitoring bandwidth usage and
> giving out intelligent rate-limiting orders.

So, why not? I think it is easier to implement that in one place than
needing to reimplement it in any pluggable transport again (or at least
once per implementation language).

After all, tor is the one who sees the total traffic anyway, and thus
is in a unique position to throttle in a fair way, for any definition
of 'fair'.

And it also means that we can throttle the regular bridge protocol
as well. Which actually makes me wonder: Why do you expect that we
need this kind of rate-limiting?


"Totally trivial. Famous last words."
From: Linus Torvalds <torvalds@*.org>
Date: Fri, 22 Jan 2010 07:29:21 -0800

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