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Just wanted to let everyone know that I am making the dynamic
whitelisting iptables rules I have been testing available to anyone
who runs a Q3-protocol server under Linux and wants to try them
out. These rules were designed for the most severe of all attacks,
and that is attacks where the source IP is spoofed and is random.
It also works for attacks from a single IP as well, as well as
indirect reflection attacks.<br>
<br>
We have 2 commercial server companies using these rules currently in
their production environment, and I am currently working with two
more. I also have test servers running on several VPS's that I use
for development.<br>
<br>
So what do the iptables do? Here's the list:<br>
<br>
1) Players have their IP saved automatically at the kernel level
when they join a game server, and then those IPs are used as a
filter for other rules. When they leave the game server the IP is
retired after 10 minutes. (This is what we call a whitelisted
player). This is the main guts of the protection, as identifying
valid players is important to mitigating attacks.<br>
<br>
2) Server query packets like 'getstatus' and 'getinfo' are rate
limited to 10/sec to prevent lag when they are used in a DOS
attack. Players that are whitelisted have their packets allowed (so
they can see server status while in game even during an attack).<br>
<br>
3) 'getchallenge' packets (normally used by a player to join the
game) are rate limited to 2/sec, to prevent lag when they are used
in a DOS attack. Players that are whitelisted always have their
requests to join the server processed. This allows a player who was
recently playing the ability to join the server again, even when the
DOSer is trying to lock down the population on the server by
spamming fake players joining.<br>
<br>
4) All other packets are rate limited per whitelisted player IP to
no more than 100/second, to prevent lag when a DOSer has stolen a
valid player IP address and is attacking with it in an attempt to
break through the whitelist rules.<br>
<br>
5) Attempts to use your game server as a reflector to attack other
game servers is blocked (due to rate limiting in 1-4).<br>
<br>
6) Reflection attack packets hitting your server are dropped (again
due to rate limiting in 1-4).<br>
<br>
7) A custom packet (not part of the Q3 protocol) can be sent by a
player to break into and join a game that is under 24/7
'getchallenge' attack. This is one of the slicker features of the
iptables rules, as this 'server lockdown' DOS attack is now easily
breached.<br>
<br>
<br>
The iptables rules are added dynamically per server IP:PORT pair.
That way the rules affect nothing but UDP packets to that game
server. No other types of packets are affected whatsoever. To make
it easy, the rules have been put into shell scripts.<br>
<br>
Example: Protect the game running on 10.1.2.3 port 28000.<br>
<br>
<tt># ./protectgame.sh 10.1.2.3 28000</tt><br>
<br>
Example: Show the iptables rules currently protecting the game
running on 10.1.2.3 port 28000.<br>
<br>
<tt># ./listgame.sh 10.1.2.3 28000</tt><br>
<br>
Example: Remove the iptables rules protecting the game running on
10.1.2.3 port 28000.<br>
<br>
<tt># ./unprotectgame.sh 10.1.2.3 28000</tt><br>
<br>
Rather than just send the scripts to the whole list here, I've
decided to ask anyone interested to Email me personally and request
it. If you run a commercial gaming service (or even your own COD
server and agree not to share it with anyone else), I will be happy
to send it to you and help you understand how to use it in your
environment.<br>
<br>
Thanks,<br>
<br>
<i>Boyd</i><br>
<div class="moz-signature"> <br>
<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>
<a class="moz-txt-link-abbreviated" href="mailto:drboyd@westportresearch.com">drboyd@westportresearch.com</a><br>
</font></i><br>
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