[tor-relays] What causes circuits to collapse?

[x9p_tor]

> Hi,
>
> I have configured a Tor bridge to go through a particular Tor guard
> relay (that I also own), as an experiment.
> Upon initialization I am getting this warning:
>
> "Your guard [fingerprint] is failing an extremely large amount of
> circuits. This could indicate a route manipulation attack, extreme
> network overload, or a bug. Success counts are 52/275. Use counts are
> 67/67. 268 circuits completed, 0 were unusable, 217 collapsed and 1
> timed out. For reference, your timeout cutoff is 60 seconds".
>

As the message says, maybe be a network issue between the bridge and the
relay. To exclude this possibility a second daemon pinging and log the
packets between the 2 machines could be a good thing to exclude this. ISPs
can fail lot of times in a day.

> Both relays are running Tor 3.0.10.
>
> I have never received this warning before. How do I interpret the
> numbers above, and debug the issue?
>

Does your relay also host a HS? Found here this could also be an issue:

https://tor.stackexchange.com/questions/9265/im-building-lots-of-circuits-what-could-cause-this

> The guard is far from saturating its network bandwidth. It has 98%
> idle CPU and plenty of free memory. I am not running any attacks
> against it. It does use a tuned-up sysctl.conf but I have never had
> any problems with it. "tcpdump icmp" does not show anything
> interesting. There are no warnings in the guard's log.
>
> Thanks,
> Igor
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