From matthew@matthew.at Fri Jul 6 02:39:53 2018 From: Matthew Kaufman To: cypherpunks-legacy@lists.cpunks.org Subject: Re: [p2p-hackers] Skype Outage Date: Fri, 06 Jul 2018 02:39:53 +0000 Message-ID: <172289076838.3849117.8486309396100209370.generated@mail.pglaf.org> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="===============3163287532913117008==" --===============3163287532913117008== Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On 12/22/2010 9:54 PM, Julian Cain wrote: > > On Dec 23, 2010, at 12:33 AM, Salman Abdul Baset w= rote: > >> On Thu, 23 Dec 2010, Julian Cain wrote: >> >>> Here I display some of todays >>> work: http://www.youtube.com/watch?v=3DYHpFIMlItrM >>> >> Cool stuff. >> >> My first guess at why Skype super node numbers are decreasing at this time= of the year are that most Skype super nodes run in universities and it is th= e end of the academic semester. So students are shutting down their machines = and Skype super nodes. Infact, it is safe to say that if the universities cra= cked down on Skype, there will not likely be enough super nodes to sustain th= e Skype network. >> > There are ~100,000 standby supernodes at any one moment also the hardcoded = supernodes are for the most part installed into universities as you state. I = believe this to be an automated event. > > If you compare which supernodes went down to those that didn't the version = numbers are similar. I've captured these packets and decrypted them and curre= ntly looking into my findings. It is fairly common knowledge that many people running the current=20 version of the Windows client experienced a crash last night at around=20 the same time. This matches Skype's public message at=20 http://blogs.skype.com/en/2010/12/skype_downtime_today.html "many of=20 them were taken offline by a problem affecting some versions of Skype".=20 Not surprisingly, a whole lot of the nodes run Windows and thus the=20 fraction of supernodes which are running Windows is also high. More clients trying to reach supernodes than there is supernode capacity=20 looks exactly like a DDOS against the supernode addresses, of course.=20 This is a common restart failure mode for all types of network=20 systems... one must always balance the reconnect backoff times between=20 the risk of flooding the servers (in this case, distributed out to=20 supernodes in a p2p system) and the user experience of taking forever to=20 reconnect after a local network outage (which may be indistinguishable=20 from a global server-side problem). > Most of the supernodes were non-responsive at ~12:00 EST. There were only ~= 2k routing traffic at the peak of this event and the network requires ~71,000= to support peak load hours. > > It will be interesting to hear what they claim happened. I'm not an official spokesperson for Skype, so I can't really say more=20 than what's in the official blog... though it does say almost exactly=20 what's above. Matthew Kaufman _______________________________________________ p2p-hackers mailing list p2p-hackers(a)lists.zooko.com http://lists.zooko.com/mailman/listinfo/p2p-hackers ----- End forwarded message ----- --=20 Eugen* Leitl leitl http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE --===============3163287532913117008==--