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Re: [tor-talk] Possible Attack on Tor speed?



> > Hi,
> > 
> > I just had an idea, how an attacker could slow down the Tor network,
> > and wanted it to discuss with you.
> > To my knowledge, there is only the BadExit and BadDirectory flag,
> > nothing like BadNode.
> > In contrast to a bad exit, which is misbehaving, how could the network
> > block a node, which has all outgoing traffic blocked?
> > Lets say, I set up some (few hundred or so) Nodes, which I start up
> > and then block outgoing traffic on them. If they're chosen as middle
> > node for a circuit, the circuit can't build, because the next server
> > cannot be reached.
> > If my servers advertise a high bandwidth (is there any detection for
> > false bandwidth advertisings?), Tor will often try to put them in a
> > circuit, and often will fail. This could lead to no usable circuit for
> > several minutes.
> > 
> > Let me know what you think!
> > 
> > Thanks :)
> 
> Dirauths can add nodes to their configuration to not add to the
> directory at all. See AuthDirReject in tor's manpage.
> 
> The other answer is that the bw auths will never manage to test
> bandwidth succesfully.
> 
> All the best
> Sebastian
> 

In addition to what Sebastian mentioned above, Tor nodes will drop and
ignore circuits that take too long to build. Check the following config
options:
LearnCircuitBuildTimeout
CircuitBuildTimeout

Rob

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