Re: Consensus drops node

[Scott Bennett <bennett@xxxxxxxxxx>]

     On Tue, 24 Mar 2009 12:28:04 +0100 From: Hans Schnehl
<torvallenator@xxxxxxxxx> wrote:
>On Mon, Mar 23, 2009 at 03:53:16PM -0700, Kyle Williams wrote:
>> Yes, I've seen this too.  The node "JanusPAv2" just dropped out of the mix
>> about 7 days ago.I wasn't too concerned since I was testing the max through
>> put of a embedded device.
>> 
>> I though it was probably something I did when I was half-awake, but now I'm
>> starting to question it a bit more...hrm..
>> Last I saw my node, it had a Guard and Fast status.  Then one morning, it
>> was gone and no traffic was passing through.
>> 
>> 
>> 
>> On Mon, Mar 23, 2009 at 2:51 PM, Hans Schnehl <torvallenator@xxxxxxxxx>wrote:
>> 
>> >
>> > Hi all,
>> >
>> > six hours ago the node 'vallenator's performance  began to decrease
>> > gradually
>> > from around 18 mbit/s to at present about 1 mbit/s.
>> >
>> > The node was running rather stable at it's upper level (see above) with an
>> > uptime
>> > of now 32 days.
>> >
>> > I did not do anything on this running machine, so I initially suspected my
>> > hoster
>> > to intercept or interfere, not necessarily with a motivation against Tor,
>> > but
>> > maybe for more or less genious technical reasons. But they did not do so.
>> >
>> > What happened is, the node was actually 'forgotte'n, or dropped out of
>> > consensus
>> > by the authoritive routers, it still is as of now. Since I do not have
>> > logging
>> > enabled I am unable to search or provide logs with possible traces of what
>> > was
>> > happening.
>> > Anybody else experiencing this?
>> >
>> > I'll keep the node running 'as is' and watch for any changes to occur
>> > within the
>> > next hours but probably I'll take the chance to rebuild a few things on
>> > that
>> > machine if if there is no change.
>> >
>> > Any ideas about this ?
>> >
>> > Regards
>> >
>> > Hans
>> >
>
>
>The node came up again by itself.  It did so after 18 hours of gradually but
>signifigantly loosing connections to the rest of the 'Tor-world' until there was
>only noise left. I assume the built in scheduled 18hourly publishing of descriptors
>caught some or all of the authorities by surprise in realising this box is still
>there and never stopped working ;). For these 18 hours the node was not listed
>in the current consensus. By now it is, again, with the number of connections
>and utilized bandwidth increasing.
>
>If you find vallenator on kprogs torstatus (trunk) this incident shows nicely
>in the graphics.
>
>Apparently there was a short but complete loss of connectivity or the node became
>unresponsive for just a few minutes in the beginning of this.  Due to the number
>of at that time already established connections, these and throughput reestablished
>very fast back on the previous level. But since the node appeared to have gone
>for the authorities, gradually connections to other nodes and the 'Tor-world'
>vanished.
>
>The blackout itself might have been caused by some apprentice (like me) practising
>to pull and reinsert plugs on the hosters side or other reasonable activity.
>
>Kyle mentioned, this happened to him when he 'was testing the max througphut of
>a embedded device' and it sounds a little like he was expecting this device to
>fail sooner or later, and maybe it didn't fail and just became unresponsive at
>the wrong moment.
>
>My node was for a short period of time unresponsive to or disconnected from the
>general network. The turn to publish descriptors fell exactly within this period
>of unresponsiveness.  So there probably were no descriptors sent to the authorities
>at the time they expected these to be there, ergo them dropping the router from
>the lists. The node didn't really notice and sat there chewing it's fingernails
>and wondering about all the evil in this world. ahemm.  Earlier versions of Tor
>did publish descriptors  when sending it a SIGHUP, but this is not possible
>anymore.  So probably presently  the only way of solving this is to either restart
>Tor, or just wait 18 hours until Tor will republish it's descriptors, and hopefully
>this doesn't happen in another unresponsive period.
>
     Very interesting!  I don't think I ever waited another 18 hours when this
happened to my tor node.  I first saw this happen in 2.1.2-alpha, I think, but
haven't seen it lately at all.
     For historical review, go to the August 2008 OR-TALK archives at

	http://archives.seul.org/or/talk/Aug-2008/threads.html

and take a look at the "SIGHUP without effect" thread with postings by Karsten
Loesing, you (Hans), and myself.


                                  Scott Bennett, Comm. ASMELG, CFIAG
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