[tor-dev] onionoo: bug in family set detection?

[teor]

> Date: Mon, 01 Jun 2015 19:20:32 +0000
> From: nusenu <nusenu at openmailbox.org>
> 
> Hi,
> 
> by comparing different methodologies of "parsing" myfamily data I
> stumbled upon differences between onionoo and compass.
> 
> After manual review I assume there is a bug in onionoo (or onionoo has
> a different opinion on what families actually are)
> 
> Example:
> 
> According to onionoo, torpidsDEevanzo [1] is part of a family with 38
> members.
> 
> It lists torpidsFRonline [2] as one of its members, that implies that
> torpidsFRonline lists torpidsDEevanzo as one of its members as well,
> but torpidsDEevanzo does _not_ list torpidsFRonline (according to
> onionoo data).
> 
> grep 'fingerprint":"0C77421C890D16B6D201283A2' details.json|grep
> 5510FC1736B16D46D3F2DDA5011995C478D42594
> (no result)
> 
> Is this a bug?
> 
> thanks
> 
> [1]
> https://atlas.torproject.org/#details/5510FC1736B16D46D3F2DDA5011995C478D42594
> 
> [2]
> https://atlas.torproject.org/#details/0C77421C890D16B6D201283A2244F43DF5BC89DD

No, it's a feature :-)

MyFamily requires bidirectional declarations to be effective. This prevents a malicious relay nominating significant portions of the Tor network as its family, in order to direct traffic to another malicious relay. (And/or slowing down the network and attempting to cause a DoS.)

In this case:

torpids relays have inconsistent MyFamily configurations.
OnionOO appears to correctly implement the bidirectional MyFamily logic, and remove inconsistent one-way MyFamily declarations.
Compass appears to believe each relay's MyFamily claims, without checking the other relay. This appears to be a fairly harmless bug in Compass, as Compass itself is not used for path selection.

teor

teor2345 at gmail dot com
pgp 0xABFED1AC
https://gist.github.com/teor2345/d033b8ce0a99adbc89c5

teor at blah dot im
OTR D5BE4EC2 255D7585 F3874930 DB130265 7C9EBBC7

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