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DDoS Attack Against Dyn Managed DNS

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Re: DDoS Attack Against Dyn Managed DNS

#411
post #272

Earlier quoted context omitted.

Awesome! Is this available as software I can install on my network? Sorry, probably a dumb question.

Nope, just point your machine or router's DNS to use opendns resolvers instead of your regular ones: 208.67.222.222 and 208.67.220.220

Do you have a link on the opendns web site that refers to those specific Ips?

Re: DDoS Attack Against Dyn Managed DNS

#412
post #386
post #214

Out of curiosity, why do caching DNS resolvers, such as the DNS resolver I run on my home network, not provide an option to retain last-known-good resolutions beyond the authority-provided time to live? In such a configuration, after the TTL expiration, the resolver would attempt to refresh from the authority/upstream provider, but if that attempt fails, the response would be a more graceful failure of returning a la…

I can guarantee you that popular DNS resolvers (think 500b+ transactions a day) do have this feature! Don't want to say much more due to it being my job, and I don't want to give away too much. EDIT: https://www.google.com/patents/US8583801

What is the point of this comment?

Re: DDoS Attack Against Dyn Managed DNS

#413
I wanted to provide an update on the PagerDuty service. At this time we have been able to restore the service by migrating to our secondary DNS provider. If you are still experiencing issues reaching any pagerduty.com addresses, please flush your DNS cache. This should restore your access to the service. We are actively monitoring our service and are working to resolve any outstanding issues. We sincerely apologize for the inconvenience and thank our customers for their support and patience. Real-time updates on all incidents can be found on our status page and on Twitter at @pagerdutyops and @pagerduty. In case of outages with our regular communications channels, we will update you via email directly.

In addition you can reach out to our customer support team at support@pagerduty.com or +1 (844) 700-3889.

Tim Armandpour, SVP of Product Development, PagerDuty

Re: DDoS Attack Against Dyn Managed DNS

#414

Earlier quoted context omitted.

No. What we need are new techniques for creating back-pressure to all the routers which are forwarding on this type of attack. The issue is that our Routing technology does not give downstream nodes any way to push back on the flood of packets. Cisco could step up to the plate here. And no, I'm not talking about firewalls. We need newer ICMP type packets to create this back-pressure, so that we can stop floods like t…

It looks like we used to have something similar but it got deprecated. https://tools.ietf.org/html/rfc6633

I was a big fan of ICMP Source Quench in the early 1980s, but it wouldn't help now. It doesn't have authentication.

Re: DDoS Attack Against Dyn Managed DNS

#415

Relevant (or at least a-propos) post by Bruce Schneier, from a month ago: "Someone Is Learning How to Take Down the Internet" https://www.schneier.com/blog/archives/2016/09/someone_is_le... Edit: And to be clear: I don't mean to imply there's any connection :)

prediction: in some time they will probe Google. That will be fascinating.

I think it's safe to assume they've been probing Google for 15+ years. One documented example: https://en.wikipedia.org/wiki/Operation_Aurora

Re: DDoS Attack Against Dyn Managed DNS

#416
post #380

Earlier quoted context omitted.

You seem to be continuing to warn against a proposal that isn't the one that was made. What specifically is dangerous about using cached records only in the case of the upstream servers failing to reply?

It doesn't take much of an imagination to attack this. The older I get in tech the more I realize we just go in circles re-implementing every bad idea over again for the same exact reasons each "generation". Ah well. TTL is TTL for a reason. It's simple. The publisher is in control, they set their TTL for 60 seconds so obviously they have robust DNS infrastructure they are confident in. They are also signaling with s…

Assume we serve the last known record after TTL.

Here's the attack:

- Compromise IP (maybe facebook.com)

- DDoS nameservers

- facebook removes IP from rotation

- Users still connect to bad actor even though TTL expired

"We have standards for a reason" is absolutely correct, and we can't start ignoring the standards because someone can't imagine why we need them _at this moment_

Re: DDoS Attack Against Dyn Managed DNS

#417

Relevant (or at least a-propos) post by Bruce Schneier, from a month ago: "Someone Is Learning How to Take Down the Internet" https://www.schneier.com/blog/archives/2016/09/someone_is_le... Edit: And to be clear: I don't mean to imply there's any connection :)

Let's try to put this DDoS attack in some context aside from the technical part. As @scrollaway mentioned, 6 weeks ago, Bruce Schneier posted that several companies told him that they're detecting attempts to probe their networks and find ways to bring it down https://www.schneier.com/blog/archives/2016/09/someone_is_le... Now let's look at the progress of events: - Hillary Clinton's personal email server was hacked…

I just want to sell my software, why does everyone have to fight?!

Thank you for these links. I'm trying not to get wrapped up in conspiracies but am increasingly worried by the mounting conflict. I'd love to hear a calm, reasoned response from someone more knowledgable than me on these topics.

Re: DDoS Attack Against Dyn Managed DNS

#418
post #386
post #214

Out of curiosity, why do caching DNS resolvers, such as the DNS resolver I run on my home network, not provide an option to retain last-known-good resolutions beyond the authority-provided time to live? In such a configuration, after the TTL expiration, the resolver would attempt to refresh from the authority/upstream provider, but if that attempt fails, the response would be a more graceful failure of returning a la…

I can guarantee you that popular DNS resolvers (think 500b+ transactions a day) do have this feature! Don't want to say much more due to it being my job, and I don't want to give away too much. EDIT: https://www.google.com/patents/US8583801

you mean opendns?

Re: DDoS Attack Against Dyn Managed DNS

#419

Earlier quoted context omitted.

I'm seeing "connection timed out; no servers could be reached". Anyone else seeing that when trying to run the above command?

did you switch your computer's dns servers to openDNS? 208.67.222.222 208.67.220.220 (or specify dns server in the command)

Yes we did dig @208.67.220.220 -t CNAME .herokussl.com. And we got the following SERVFAIL error:

; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION: ;.herokussl.com. IN CNAME

;; Query time: 1226 msec ;; SERVER: #53() ;; WHEN: Fri Oct 21 12:27:55 2016 ;; MSG SIZE rcvd: 44

Re: DDoS Attack Against Dyn Managed DNS

#420

Earlier quoted context omitted.

> i seem to remember that dns has generally been reliable (until recently, i guess) Probably because people used to use long TTLs (1 hour, 4 hours, whatever) and now the default behavior in services like Amazon Route 53 is to use 5 minutes.

Try Akamai managed CDN content. 20 seconds !!

The 20 seconds with Akamai is because of their dynamic end user IP mapping technology, Basically they need to map in near real-time based on characteristics of the end user IP, they can't afford a long TTL
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