[Pool] DDoS Type Attack

Clay Fiske clay at bloomcounty.org
Fri Feb 14 18:59:50 UTC 2014


On Feb 14, 2014, at 8:43 AM, Mouse <mouse at Rodents-Montreal.ORG> wrote:

>> If you are saying that normal NTP time queries should be forbidden to
>> those behind NAT routers, you are stopping about 99% of those I know
>> who are using NTP from doing so.  I hope this was not your intention,
>> or that I have somehow otherwise mis-understood.
> 
> No, not that they should be prevented.  Just that if it _doesn't_ work,
> it's their own fault - that is, when I see "this works without NAT and
> breaks with NAT", my reaction is much more "don't do that, then" than
> "the peer should be fixed".

So all I need to do is write a client that uses a non-123 source port and you’ll support fixing it? Great. :)

I dislike NAT as much as the next person, but it is a reality in a lot of places and is often not up to the people who desire NTP synchronization whether they are behind a NAT device. And to be clear, NAT is not breaking it in this situation. Someone’s deliberate firewall rule is breaking it. So more like “this works without your arbitrary rule and breaks with it”.

Also it only takes a simple tweak and this rule becomes ineffective even at its intended purpose. If the attacker is able to spoof the source IP, you can bet they’re not prevented from using source port 123 either.

-c



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