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Mark Andrews wrote:
In article <43C9EF72.50803@garlic.com> you write:
I just started seeing thousands of DNS queries that look like some sor= t=20 of DOS attack. One log entry is below with the IP obscured.
client xx.xx.xx.xx#6704: query: z.tn.co.za ANY ANY +E
When you look at z.tn.co.za you see a huge TXT record.
Is anyone else seeing this attack or am I the lucky one? Is this a=20 known attack?
Roy =20 You are being used as a DoS amplifier. The queries will be spoofed. Someone needs to learn about BCP 38.
Next to not running a $world recursive/caching service ;) Which is where the OP can actually do something about this problem. Folks who don't do ingress filtering will not be bothered to get it going unfortunately...
Greets, Jeroen
Configure the server to serve z.tn.co.za and set "allow-query { none; };". This will stop the server amplifying the attack. Black-hole the spoofed address. This works fine for purely recursive servers as they shouldn't be getting queries from the given address anyway. On could hack the servers to identify particular tuples and black-hole them. This however is a not a long term solution to the problem and requires a lot of maintenance. Trace the spoofed traffic streams and get the offending sites turned off recommending that BCP 38 be depoloyed. For repeat offenders create a list of networks that won't implement BCP 38 and collectively de-peer with them telling them why you are de-peering and what is required to re-establish connectivity. It is in everyones interests to do the right thing here. Shunning works if you have the collective gumption to do it. Alternatively create a list of networks that agree to implement BCP 38 and don't carry traffic from anyone else. Advertise that you are BCP 38 compliant. Either way, lack of BCP 38 compliance is a collective problem and needs to dealt with in a collective manner. Mark -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: Mark_Andrews@isc.org