DDoS using port 0 and 53 (DNS)
frnkblk at iname.com
Wed Jul 25 04:50:06 UTC 2012
Thanks for confirming what was discussed in the NANOG archive.
I now have warm fuzzies knowing that all my protections are reactive. =) I will be talking with our upstream provider to see if they can enable some better automation (because they run a larger shop). I know they were able to null route in seconds, we just need a faster way to identify targets.
From: Roland Dobbins [mailto:rdobbins at arbor.net]
Sent: Tuesday, July 24, 2012 11:06 PM
To: Frank Bulk; nanog at nanog.org
Subject: Re: DDoS using port 0 and 53 (DNS)
Frank Bulk <frnkblk at iname.com> wrote:
>Unfortunately I don't have packet captures of any of the attacks, so I
>can't exam them for more detail, but wondering if there was some
>collective wisdom about blocking port 0.
Yes - don't do it, or you will break the Internet. These are non-initial fragments.
You or your customers are on the receiving end of DNS reflection/amplification attacks, and the large unsolicited DNS responses being used to packet you/them are fragmented. Use S/RTBH, flowspec, IDMS, and/or coordination with your peers/upstreams to block these attacks when they occur.
Do *not* perform wholesale blocking of non-initial fragments (i.e., src/dst port 0), or you will have many unhappy customers and soon-to-be former customers.
Roland Dobbins <rdobbins at arbor.net>
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