On 05/11/13 03:54, Justin wrote:
> I have two machines that participate in the ntp pool project, and I
> received an abuse email today. Basically, my server was DDOS someone
> else, ntp reflection attack.  Obviously that is not something I want to
> do.  By default my ntp server allows any that connect to port 123. 
> These ddos were sending the responses back to someone's port 80, which
> is causing me the headache.  My first step will be to lock the ntp down
> to port 123 and ports above 1024 for people behind a nat.  I was also
> going to place iptables rate limit.  Is there anything else I should be
> doing? I have read about the restrict limited and discard statement in
> ntp.conf, but I'm not sure if that will help here. All my solutions have
> been outside ntp.conf, so I know I have to be overlooking something.  I
> have never had problems with aggressive clients or ntp reflection dos
> before.  I also really do not care about aggressive clients even now.
> The system particulars, Ubuntu 13.10/x86, which uses ntp
> 4.2.6.p5+dfsg-3ubuntu2.  Any assistance is welcomed.


The long term answer is for all network operators worldworld to
implement BCP38

http://tools.ietf.org/html/bcp38

This limits the outflow of spoofed packets.


Tim
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