nanog mailing list archives

Re: OpenNTPProject.org


From: Derek Andrew <Derek.Andrew () usask ca>
Date: Mon, 13 Jan 2014 15:13:18 -0600

nmap -sU -pU:123 -Pn -n --script=ntp-monlist serverIP




On Mon, Jan 13, 2014 at 3:07 PM, Jared Mauch <jared () puck nether net> wrote:

Greetings,

With the recent increase in NTP attacks, I wanted to advise the community
of a few things:

There are about 1.2-1.5 million of these servers out there.

1) You can search your IP space to find NTP servers that respond to the
‘MONLIST’ queries.

2) I’ve found some vendors have old embedded versions of NTP including
ILO/Service Processors and other parts of the “internet of things”.

3) You want to upgrade NTP, or adjust your ntp.conf to include ‘limited’
or ‘restrict’ lines or both.  (I defer to someone else to be an expert in
this area, but am willing to learn :) )

4) Please prevent packet spoofing where possible on your network.  This
will limit the impact of spoofed NTP or DNS (amongst others) packets from
impacting the broader community.

5) Some vendors don’t have an easy way to alter the ntp configuration, or
have not or won’t be updating NTP, you may need to use ACLs, firewall
filters, or other methods to block this traffic.  I’ve heard of many
routers being used in attacks impacting the CPU usage.

Take a moment and see if your devices respond to the following
query/queries:

ntpdc -n -c monlist 10.0.0.1
ntpdc -n -c loopinfo 10.0.0.1
ntpdc -n -c iostats 10.0.0.1

6) If you do VMs/Servers and have a template, please make sure that they
do not respond to NTP requests.

Thanks!

- Jared




-- 
Copyright 2014 Derek Andrew (excluding quotations)

+1 306 966 4808
Information and Communications Technology
University of Saskatchewan
Peterson 120; 54 Innovation Boulevard
Saskatoon,Saskatchewan,Canada. S7N 2V3
Timezone GMT-6

Typed but not read.


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