[tor-relays] excessive bandwidth assigned bandwidth-limited exit relay

[Tim Wilson-Brown - teor]

> On 3 Oct 2015, at 19:09, Dhalgren Tor <dhalgren.tor at gmail.com> wrote:
> 
> Was going to wait a few days before reporting back, but early results
> are decisive.
> 
> The overload situation continued to worsen over a two-day period, with
> consensus weight continuing to rise despite the relay often running in
> a state of extreme overload and performing its exit function quite
> terribly.
> ...
> The bandwidth measurement system now looks like a secondary issue.
> The big problem is that Tor daemon bandwidth throttling sucks and
> should be avoided in favor of Linux kernel rate-limiting where actual
> bandwidth exceeds bandwidth allocated to Tor, whatever the motivation.
> TCP is much better at dealing with congestion than the relay internal
> limit-rate logic.
…

You might find Rob Jansen's KIST paper interesting reading - it is about making Tor aware of kernel buffers.
(Currently, Tor doesn’t know what happens after it writes data to the socket.)

http://www.robgjansen.com/publications/kist-sec2014.pdf <http://www.robgjansen.com/publications/kist-sec2014.pdf>

Tim

Tim Wilson-Brown (teor)

teor2345 at gmail dot com
PGP 968F094B

teor at blah dot im
OTR CAD08081 9755866D 89E2A06F E3558B7F B5A9D14F

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