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If every Linux server had the iptables getstatus reflection throttle
rule, it would be harder to do massive reflection attacks like
this. <br>
<br>
Unfortunately, even if every Linux admin did this, there would still
be at least 20 servers that don't, and the attackers would just pick
the ones that don't to do the attack.<br>
<br>
Such a pain.<br>
<br>
:(<br>
<br>
On 02/23/2012 06:15 PM, NewLight Systems wrote:
<blockquote cite="mid:4F46D684.7070104@newlightsystems.com"
type="cite">
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Yes that's very annoying . The problem is that is very easy to do
a distributed attack with this gameserver's bugs.<br>
<br>
And of course, any gameserver is probably on a dedicated line with
100 or 1000 MBPS bandwidth, so 20 "zombie" gameservers throwing
reflection attacks = 50 MBPS = 1 GBPS of distributed attack.<br>
<br>
I don't mind our cpus, are fast, but we are real capped at the
bottleneck that represents 1 GBPS of fast ethernet<br>
<br>
El 24/02/12 00:15, Boyd G. Gafford Ph.D. escribió:
<blockquote cite="mid:4F46C888.7000104@westportresearch.com"
type="cite">
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Yep, thats getting towards the saturated side lol. It must be a
distributed DOS UDP flood, as I can't imagine many script
kiddies with that kind of bandwidth for a single attack spoofing
20 IPs.<br>
<br>
At that point, a lot of your CPU is just handling the incoming
IP packets. Not much to do in that situation. Even if you
bonded four GbE's together, you're still looking at needing
quite a chunk of CPU just to offload throwing away that 1Gbps.<br>
<br>
Even if you were to dynamically interact with your router to
tell it to drop the packets, your incoming bandwidth would still
be hammered. It almost has to happen at the carrier (preferably
at the carriers of the flooders) to do anything to help, and we
all know how likely that is to happen unfortunately.<br>
<br>
Good luck,<br>
<br>
<i>Boyd</i><br>
<div class="moz-signature"><br>
</div>
<br>
On 02/23/2012 04:46 PM, NewLight Systems wrote:
<blockquote cite="mid:4F46C1B5.2060601@newlightsystems.com"
type="cite">
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The problem is that we are receiving for example 1 GBPS
attacks to one IP from serveral sources ( maybe 15 - 20 ips )<br>
<br>
That means that 1 GB of inbound is occupied. We have iptables
rules, of course, but is affecting all services on that
dedicated server<br>
<br>
El 23/02/12 23:42, Boyd G. Gafford Ph.D. escribió:
<blockquote cite="mid:4F46C0C1.60803@westportresearch.com"
type="cite">
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Hey there, thanks for responding.<br>
<br>
I'm not sure I understand what you mean by "the line is
occupied anyway." If you mean the bandwidth to the server
is saturated by the flood, then yeah, its going to affect
game play. Fortunately most servers at data centers have
high enough bandwidth to them that a typical attack doesn't
saturate.<br>
<br>
If your game server port is the target of a single IP UDP
flood attack, then typically an iptables drop rule handled
by the kernel is more efficient than the game server itself,
especially if the flooded packets are server commands that
are being processed by the game server, which is sending out
UDP reply packets. That takes up much more CPU than a
kernel-level packet drop.<br>
<br>
Under those circumstances, the cheap VPS we use in Dallas
has endured 64Mbps attacks for hours and the game server is
still very playable. It would be nice if the flood was
blocked at the router or carrier level, but still iptables
is pretty amazing when the kernel drop is your last line of
defense.<br>
<br>
Thanks,<br>
<br>
<i>Boyd</i><br>
<br>
<br>
On 02/23/2012 04:22 PM, NewLight Systems wrote:
<blockquote cite="mid:4F46BC41.4010505@newlightsystems.com"
type="cite">
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It's ok but this isn't working if the UDP floods to your
server because the line is occupied anyway.<br>
<br>
If you are the target, there's nothing you can do in a
dedicated server level.<br>
<br>
This type of attack ( allways if you are the target ) have
to be erradicated in a higher level ( router or carrier )
if you want to preserve your connection<br>
<br>
El 23/02/12 23:12, Boyd G. Gafford Ph.D. escribió:
<blockquote
cite="mid:4F46B9E7.2030501@westportresearch.com"
type="cite">
<meta http-equiv="content-type" content="text/html;
charset=ISO-8859-1">
Hey everyone, EscapedTurkey told me about this group,
and so I Just wanted to say a quick hello.<br>
<br>
I'm the guy who got frustrated enough with UDP flood
attacks that I wrote ServerArk to deal with the majority
of them. If anyone has any questions about the program,
or any ideas on what they would like to see in it in the
future, by all means let me know.<br>
<br>
Since I've been using it on our JA (Q3 protocol) servers
(<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://elitewarriors.net">http://elitewarriors.net</a>)
its blocked about 20 high volume attacks (one at 64Mbps)
successfully over the past few months. As long as the
source IP of the UDP flood is not random, it works
really well.<br>
<br>
I have a few new ideas on flood detection on random IP
attacks I will ping off your guys over the next few days
to see what you think.<br>
<br>
Also kudos to whoever did the "I don't want to
participate in reflection attacks" iptables rule that
matches off of the 'getstatus' UDP packet payload. If
everyone who had a Q3 protocol server (COD, JA, etc) had
that rule running reflection attacks would be a LOT less
potent.<br>
<br>
:)<br>
<br>
Thanks,<br>
<br>
<i>Boyd</i><br>
<br>
<div class="moz-signature"><i><font size="-1">__________________________________<br>
Boyd G. Gafford Ph.D.<br>
Manager of Software Development<br>
Westport Research Associates Inc.<br>
7001 Blue Ridge Blvd<br>
Raytown, MO 64133<br>
(816) 358-8990<br>
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