[tor-dev] Guard node security: ways forward (An update from the dev meeting)

[George Kadianakis]

Nicholas Hopper <hopper at cs.umn.edu> writes:

> On Tue, Feb 25, 2014 at 5:04 PM, Nicholas Hopper <hopper at cs.umn.edu> wrote:
>> Another thought: we also should investigate how various thresholds
>> affect the relationship between the cumulative guard weight total and
>> the total exit weight.
>
> Well, that turns out not to be a real issue: even if we set the guard
> threshold to 20MBps, the total guard weight still exceeds the total
> exit weight.
>
> Here is a chart showing what fraction of total guard bandwidth is
> retained as we vary the guard threshold from 0 to 10MBps:
>
> https://www-users.cs.umn.edu/~hopper/guards/guard_thresholds_bandwidth.png
>
> And here's a chart showing what fraction of clients will choose the
> highest (max%) and median (median%) guards as we vary the threshold
> over the same range:
>
> https://www-users.cs.umn.edu/~hopper/guards/guard_thresholds_weight.png
>
> 2MBps and 6MBps look like interesting points on the curves.

Thanks, these are useful graphs.

And here is another one with the number of guard nodes over different
cutoff values:

https://people.torproject.org/~asn/guards/guard_number_cutoff.png

We will want to choose a cutoff value that doesn't discard too many
guard nodes.