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<h1 class="entry-title" itemprop="headline" ><a href="https://sreweekly.com/sre-weekly-issue-45/">SRE Weekly Issue #45</a></h1>
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<i class="genericon genericon-day"></i><a class="updated" href="https://sreweekly.com/sre-weekly-issue-45/">October 23, 2016</a>
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<a href="https://sreweekly.com/sre-weekly-issue-45/" title="Permalink to SRE Weekly Issue #45" class="email_only">View on sreweekly.com</a>
<p>This past Friday, it was as if Oprah were laughing maniacally, shouting, &#8220;You get an outage, and you get an outage, <a href="https://youtu.be/GNhoFaHU3_A">EVERYONE GETS AN OUTAGE</a>!&#8221; Hat-tip to all of you who spent the day fighting fires like I did.</p>
<p>I&#8217;ve decided to dedicate this week&#8217;s issue entirely to the incident, the fallout, and information on redundant DNS solutions. I&#8217;ll save all of the other great articles from this week for the next issue.</p>
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<h2>Articles</h2>
<div class="sreweekly-entry">
<div class="sreweekly-title"><a href="http://www.theregister.co.uk/2016/10/21/dns_devastation_as_dyn_dies_under_denialofservice_attack/" target="_blank">DNS devastation: Top websites whacked offline as Dyn dies again</a></div>
<div class="sreweekly-description">
<p>The Register has a good overview of the attacks.</p>
</div>
</div>
<div class="sreweekly-entry">
<div class="sreweekly-title"><a href="http://hub.dyn.com/static/hub.dyn.com/dyn-blog/dyn-statement-on-10-21-2016-ddos-attack.html" target="_blank">Dyn Statement on 10/21/2016 DDoS Attack</a></div>
<div class="sreweekly-description">
<p>Dyn released this statement on Saturday with more information on the outage. Anecdotally (based on my direct experience), I&#8217;m not sure their timeline is quite right, as it seems that I and others I know saw impact later than Dyn&#8217;s stated resolution time of 1pm US Eastern time. Dyn&#8217;s <a href="https://www.dynstatus.com/incidents/nlr4yrr162t8">status post</a> indicates resolution after 6pm Eastern, which matches more closely with what I saw.</p>
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<div class="sreweekly-entry">
<div class="sreweekly-title"><a href="http://status.aws.amazon.com/" target="_blank">AWS</a></div>
<div class="sreweekly-description">
<p>Among many other sites and services, AWS experienced an outage. They posted an unprecedented amount of detail <i>during the incident</i> in a banner on their status site. Their status page history doesn&#8217;t include the banner text, so I&#8217;ll quote it here:</p>
<blockquote><p>These events were caused by errors resolving the DNS hostnames for some AWS endpoints. AWS uses multiple DNS service providers, including Amazon Route53 and third-party service providers. The root cause was an availability event that occurred with one of our third-party DNS service providers. We have now applied mitigations to all regions that prevent impact from third party DNS availability events.</p></blockquote>
<p>Nice job with the detailed information, AWS!</p>
</div>
</div>
<div class="sreweekly-entry">
<div class="sreweekly-title"><a href="https://krebsonsecurity.com/2016/10/ddos-on-dyn-impacts-twitter-spotify-reddit/" target="_blank">DDoS on Dyn Impacts Twitter, Spotify, Reddit</a></div>
<div class="sreweekly-description">
<p>Krebs on Security notes that the attack came hours after a talk on DDoS attacks at NANOG. Krebs was a previous target of a massive DDoS, apparently in retaliation for his publishing of research on DDoS attacks.</p>
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</div>
<div class="sreweekly-entry">
<div class="sreweekly-title"><a href="https://www.pagerduty.com/blog/initial-outage-report/" target="_blank">PagerDuty</a></div>
<div class="sreweekly-description">
<p>Paging through PagerDuty was down or badly broken throughout Friday. Many pages didn&#8217;t come through, and those that did sometimes couldn&#8217;t be acknowledged. Some pages got stuck and PagerDuty&#8217;s system would repeatedly call engineers and leave the line silent. [source: personal experience] Linked is PagerDuty&#8217;s &#8220;Initial Outage Report&#8221;. It includes a preliminary explanation of what went wrong, an apology, and a pledge to publish two more posts: a detailed timeline and a root cause analysis with remediation items.</p>
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<div class="sreweekly-entry">
<div class="sreweekly-title"><a href="https://www.sumologic.com/blog-devops/survived-dyn-dns-outage/" target="_blank">How We Survived the Dyn DNS Outage</a></div>
<div class="sreweekly-description">
<p>Sumo Logic implemented dual nameserver providers after a previous DNS incident. This allowed them to survive the Dyn outage relatively unscathed.</p>
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</div>
<div class="sreweekly-entry">
<div class="sreweekly-title"><a href="http://www.politico.com/story/2016/10/websites-down-possible-cyber-attack-230145" target="_blank">WikiLeaks supporters claim credit for massive U.S. cyberattack, but researchers skeptical</a></div>
<div class="sreweekly-description">
<p>Anonymous and New World Hackers have claimed responsibility for Friday&#8217;s attack, but that claim may be suspect. Their supposed reasons were to &#8220;retaliate for the revocation of Julian Assange&#8217;s Internet access&#8221; and to &#8220;test their strength&#8221;.</p>
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</div>
<div class="sreweekly-entry">
<div class="sreweekly-title"><a href="http://www.ibtimes.co.uk/wikileaks-urges-supporters-stop-taking-down-us-internet-following-massive-ddos-attack-1587718" target="_blank">WikiLeaks urges supporters to &#8216;stop taking down the US internet&#8217; following DDoS cyberattack</a></div>
<div class="sreweekly-description">
<p>WikiLeaks bought their claim and asked supporters to cut it out.</p>
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<div class="sreweekly-entry">
<div class="sreweekly-title"><a href="https://technet.microsoft.com/en-us/library/cc961401.aspx" target="_blank">Recursive and Iterative Queries</a></div>
<div class="sreweekly-description">
<p>A great basic overview of how recursive DNS queries work, published by Microsoft.</p>
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</div>
<div class="sreweekly-entry">
<div class="sreweekly-title"><a href="http://www.zytrax.com/books/dns/ch2/" target="_blank">Chapter 2 DNS Concepts, from Pro DNS and Bind by Ron Aitchison</a></div>
<div class="sreweekly-description">
<p>A much more detailed explanation if how DNS works. Recursive and iterative DNS queries are covered in more depth, along with AXFR/IXFR/NOTIFY which can be used to set up a redundant secondary DNS provider for your domain.</p>
</div>
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<div class="sreweekly-entry">
<div class="sreweekly-title"><a href="https://status.heroku.com/incidents/965" target="_blank">Heroku Status Site Incident 965: Issues with DNS resolution</a></div>
<div class="sreweekly-description">
<p>Heroku was among many sites impacted by the attack. Heroku&#8217;s status site was also impacted, prompting them to create a temporary mirror. This is painfully reminiscent of an article linked two issues ago about <a href="http://www.circleid.com/posts/20161006_how_to_handle_an_outage_like_a_pro/">making sure your DNS is redundant</a>.</p>
<p><small><em>Full disclosure: Heroku is my employer.</em></small></p>
</div>
</div>
<div class="sreweekly-entry">
<div class="sreweekly-title"><a href="http://blog.easydns.org/2010/08/19/dos-attacks-and-dns-how-to-stay-up-if-your-dns-provider-goes-down/" target="_blank">DOS Attacks and DNS: How to Stay Up If Your DNS Provider goes DOWN</a></div>
<div class="sreweekly-description">
<p>EasyDNS has this guide on setting up redundant DNS providers to safeguard against an attack like this. However, I&#8217;m not sure about their concept of &#8220;fast fluxing&#8221; your nameservers, that is, changing your nameserver delegation with your registrar when your main DNS provider is under attack.</p>
<p>Unless I&#8217;m mistaken, a change in nameservers for a domain can take up to 2 days (for .com) to be seen by all end-users, because their ISP&#8217;s recursive resolver could have your domain&#8217;s NS records cached, and the TTL given by the .com nameservers is 2 days.</p>
<p>Am I missing something? Maybe recursive resolvers optimistically re-resolve your domain&#8217;s NS records if all of your nameservers time out or return SERVFAIL? If you know more about this, <i>please</i> write to me!</p>
</div>
</div>
<h2>Outages</h2>
<p>I&#8217;m not going to bother naming all of the many sites and services that went down on Friday, because there were too many and I&#8217;d inevitably miss some. The below outages all occurred earlier in the week.</p>
<ul class="sreweekly-outages">
<li><a href="http://411mania.com/games/playstation-network-goes-down-after-call-of-duty-infinite-warfare-beta-release/">PSN</a></li>
<li><a href="http://mashable.com/2016/10/19/new-york-times-website-down/">The New York Times</a></li>
<li><a href="http://status.cloud.google.com/incident/compute/16020#5676325415157760">Google Compute Engine Load Balancers</a>
<ul class="sreweekly-outage">
<li class="sreweekly-outage">GCE&#8217;s LB offering returned progressively more 502s over the course of 2 hours, with a peak of 45% of requests failing. Linked is Google&#8217;s postmortem of the incident, which seems to have been a bad deploy.</li>
</ul>
</li>
<li><a href="http://australianaviation.com.au/2016/10/virgin-australia-website-back-up-and-running-after-sabre-outage/">Virgin Australia website</a></li>
</ul>
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