On Mar 3, 2009, at 7:53, der Mouse wrote:

> I'm now collecting data from my own pool host to see if I see  
> similar spikes in people fetching time.


I don't think you will; as Nelson said then most of the actual clients  
are (for better or worse) doing a few DNS lookups and then using those  
IPs for a long long time.   The DNS spikes are from ntpdate/sntp  
clients.   Really then the query rates for the DNS is low enough that  
just a few thousand clients setup to sync on the top of the hour can  
account for those spikes.

> I found my DNS server being abused as a DDoS reflector; someone was
> sending queries (for TXT records for aol.com. - why that, I don't  
> know)

(They're hoping you'd resolve it and return the unusually large  
response to the victim; the usual one they use is NS for "."; but txt  
for aol.com is bigger...).

[...]
> My questions for the list are, (1) does this match others' experience?
> and (2) what's the list's opinion on whether this is a reasonable  
> thing
> to do on a pool server, and, if so, on my choice of trip point?

IIRC then it's not clear if blocking the packets actually help or just  
make them increase.  :-(



  - ask

-- 
http://develooper.com/ - http://askask.com/


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