I see some attributes in the "UNIX ntpd" example there which are missing. I would suggest people follow the defaults provided by some of the OSS distros (ex. FreeBSD 9): http://svnweb.freebsd.org/base/stable/9/etc/ntp.conf?revision=259974&view=ma... Specifically these lines for starters: restrict default kod nomodify notrap nopeer noquery restrict -6 default kod nomodify notrap nopeer noquery restrict 127.0.0.1 restrict -6 ::1 restrict 127.127.1.0 The last 3 lines are effectively "allow" statements. You'll need to modify your ntp.conf accordingly; e.g. if the system in question is used as an NTP server for other machines on 192.168.1.0/24, you'd need something like: restrict 192.168.1.0 mask 255.255.255.0 But I recommend folks read (not skim -- it actually reads quite easily, just the formatting isn't easily skimmable) the following page, as it goes over the difference between "restrict default {bunch of modifiers}" vs. "restrict default ignore": http://support.ntp.org/bin/view/Support/AccessRestrictions It's remarkable how neglected NTP is as a service. :/ -- | Jeremy Chadwick jdc@koitsu.org | | UNIX Systems Administrator http://jdc.koitsu.org/ | | Making life hard for others since 1977. PGP 4BD6C0CB | On Wed, Feb 12, 2014 at 11:37:00AM -0700, John wrote:
On 02/12/2014 11:33 AM, Bryan Inks wrote:
Good info, I'll definitely be looking into this.
But, I'm not being directly attacked. Internap is one of my upstreams, and they are the one that reported that they were being attacked when we called to let them know about the problem.
*From:*Bill Wichers [mailto:billw@waveform.net] *Sent:* Wednesday, February 12, 2014 10:27 AM *To:* Jared Mauch; Bryan Inks *Cc:* outages@outages.org *Subject:* RE: [outages] Internap Being DDoS'd
To second Jared on this one, we've seen a HUGE increase in NTP-based attacks over the past several weeks with our colo customers. It's very efficient too -- even a pretty low end machine can saturate a 100M link. It reminds me of SQL slammer...
If you haven't yet checked that you're safe from this you should. See:
https://www.us-cert.gov/ncas/alerts/TA14-013A
and
https://www.us-cert.gov/ncas/alerts/TA14-017A
for more info...
And some info on how to mitigate it so you are not a reflector.
http://www.team-cymru.org/ReadingRoom/Templates/secure-ntp-template.html
--John
-Bill
*From:*Outages [mailto:outages-bounces@outages.org] *On Behalf Of *Jared Mauch *Sent:* Wednesday, February 12, 2014 1:21 PM *To:* Bryan Inks *Cc:* outages@outages.org <mailto:outages@outages.org> *Subject:* Re: [outages] Internap Being DDoS'd
Close your NTP amplifiers and prevent the spoofing.. Will solve this one.
Openntpproject.org <http://Openntpproject.org> can help you.
Jared Mauch
On Feb 12, 2014, at 12:45 PM, "Bryan Inks" <Binks@keyinfo.com <mailto:Binks@keyinfo.com>> wrote:
Just got confirmation from Internap NOC that they are being attacked again.
Causing quite a bit of chaos for my network in SoCal.
I'm having to route over to Level3 to minimize the issue.
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