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Dan Staples:
This morning I got my first Tor traffic flood since upgrading to 2.4.x. Logs didn't say anything about not being able to handle the amount of circuit creation requests, but it showed a 200x increase in active TAP circuits (~400k/hour) and the traffic pattern is the same: Advertising 100kb bandwidth, but slammed with ~2Mb traffic.
When I saw it, I checked my relay's flags, and it has the stable flag, and has been tagged stable for at least 3 days. It's been up for 7 days.
I would love to contribute data to help correlate w/ your findings Gordon. Any metrics or logs that would be particularly helpful? I currently use NTop to measure traffic, but it's not very granular.
I'm still trying to scratch together enough time to analyze the logs from the two floods I caught as they began in the past 10 days or so. One thing I am logging, which you're definitely not, is hosts that send SYNs above the limit on my Raspberry Pi. Are you running on a slow machine or a VPS or what? That might not apply to you if you're not running on a slow machine - you may have no need to limit SYNs or anything else, and that's probably the case if your relay did not crash as a result of the flood.
During my last two floods, the relay survived the first (poorly, with fail2ban becoming useless and chewing up half the CPU), and was headshotted by the second - crash in less than 5 minutes.
I'm looking forward to getting the data together and providing a report for the community, but time ... my kingdom for the time to do anything beyond work, sleep, eat, sh*t.
I also currently don't use any iptables rules to throttle, but am happy to experiment with that if you want me to try out any particular configurations.
Depends on the capacity of your hardware. All my experimentation has to do with low-end ARM boards, so the logs most useful to the report *I* am planning to prepare on these events are logs of SYN exceeds, and fail2ban logs.
Thanks very much for staying up to date and offering to contribute - there is a real problem someplace, but it seems to be mostly a Problem with a capital P for low-end hardware with 512MB physical RAM, since those are the relays likely to actually crash as a result of the floods.
Best, - -Gordon M.
Dan
On 11/01/2013 05:30 PM, Gordon Morehouse wrote:
huh, well, near as I can tell, I didn't get Stable for any time represented yesterday (2013-10-31) for the node VastCatbox.
So maybe that theory is incorrect. In that case I don't know what would trigger the SYN flood behavior other than Roger's idea about becoming an introducer for a popular HS, but... eh... seems like a stretch, a node offering 2.5Mbps that isn't flagged Stable?
-Gordon
On Fri, 1 Nov 2013 13:10:17 +0100, David Serrano tor@dserrano5.es wrote:
On 2013-10-31 10:04:02 (-0700), Gordon Morehouse wrote:
I can't verify it, but my suspicion is this is happening when I get my Stable flag (I have no idea if I'd gotten it back this morning or not) or shortly thereafter.
You can use https://metrics.torproject.org/relay-search.html and enter your IP address to figure that out.
-- David Serrano GnuPG id: 280A01F9 _______________________________________________ tor-relays mailing list tor-relays@lists.torproject.org https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays
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