[tor-bugs] #6133 [Torflow]: bwauths need to let us know when they've been running long enough

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#6133: bwauths need to let us know when they've been running long enough
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 Reporter:  arma         |          Owner:  aagbsn
     Type:  enhancement  |         Status:  new   
 Priority:  normal       |      Milestone:        
Component:  Torflow      |        Version:        
 Keywords:               |         Parent:  #2286 
   Points:               |   Actualpoints:        
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Comment(by arma):

 Replying to [comment:1 mikeperry]:
 > We have a timestamp at the top of the file already. The time value there
 is the measurement timestamp of the most recently measured relay. The
 authorities ignore the file if the timestamp is more than 3 days old.
 >
 > Not exactly what you want, I guess, but also note that the bandwidth
 authorities also don't output a measurements file in the first place if
 they don't have measurements for some percentage of the current consensus
 (MIN_REPORT = 60 in aggregate.py).
 >
 > Are these two enough? Should we tweak these parameters?

 Sounds like we want slightly different behavior. For example, if the
 bandwidths file was last written within 3 days ago, but bwauth decides
 it's not comfortable providing opinions right now, does that mean the dir
 auths use the old opinions? I think it does, and if bwauth isn't
 comfortable because it doesn't feel it has enough opinions, then using the
 outdated opinions for days is probably even worse.

 Also, it looks like we *are* vulnerable currently to the "flood the
 network with new relays so the bwauths will all stop providing Measured
 opinions" attack.

 I can see the ">=60% threshold" being there as a defense mechanism against
 a bug. But ultimately we should try to get rid of it I think.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/6133#comment:2>
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