Tightened DNS security question re: DNS amplification attacks.

Steve Pirk orion at pirk.com
Wed Jan 28 01:49:05 UTC 2009

On Wed, 28 Jan 2009, jay at miscreant.org wrote:

> Quoting John Martinez <jmartinez at zero11.com>:
>> Are we still seeing DNS DDoS attack?
> Yep. I'm seeing ~2 queries/sec targetting
> Also seeing requests from every 1 minute 2 seconds.

I run a small personal nameserver and even I am seeing requests for that 
address at ~1/sec.

How many people have upgraded to the latest version of Bind 9? Reason
I ask is that when I do my nightly port scan of my server, I no longer see 
named listening to udp on a random high order port (for replies I believe?). 
Almost the next day, I started hearing about/seeing these DNS attacks.

Previous nmap scan showed:
53/tcp    open          domain
53/udp    open|filtered domain
33591/udp open|filtered unknown

Now nmap shows:
53/tcp    open          domain
53/udp    open|filtered domain

The listen port (> 32767 I believe) is no longer there with BIND 9.4.3-P1.
The port was bound at startup time and did not change as long as named was 
still running.
Equal bytes for women.

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