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Limit per IP is done via the --hashlimit module, and the kernel can
get hit hard if try to hash millions of random IPs and allocate the
memory for them.<br>
<br>
If there is another way to limit by IP besides --hashlimit that
doesn't require dynamic allocation I'm all ears!<br>
<br>
Thanks,<br>
<br>
<i>Boyd</i><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>
<a class="moz-txt-link-abbreviated" href="mailto:drboyd@westportresearch.com">drboyd@westportresearch.com</a><br>
</font></i><br>
</div>
<br>
On 03/09/2012 03:23 PM, Ruediger Meier wrote:
<blockquote cite="mid:201203092223.05774.sweet_f_a@gmx.de"
type="cite">
<pre wrap="">On Friday 09 March 2012, Boyd G. Gafford Ph.D. wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Yeah, if they flood "getstatus" and "getinfo", during the attack your
server will not be visible from the master list.
If they flood "getchallenge", during the attack nobody will be able
to join your server.
Once the attack ends, then you'll be visible again and people can
join normally.
</pre>
</blockquote>
<pre wrap="">
</pre>
<blockquote type="cite">
<pre wrap="">Since most of these attacks are from spoofed random IP addresses
(millions of them), you can't limit per IP, as no IP repeats.
</pre>
</blockquote>
<pre wrap="">
Maybe you should do limit_per_IP_per_second AND limit_per_second where
limit_per_second is greater than the other one.
</pre>
<blockquote type="cite">
<pre wrap="">This set of rules is about the best I've found short of doing a
whitelisted server, where you only allow IP's of known good players,
and block everything else, and then people have to join the server
with "connect IP:PORT". That's fairly inconvenient for most players,
so these rules are about as good as you can get and still allow usage
from the master list.
Thanks,
/ Boyd/
/__________________________________
Boyd G. Gafford Ph.D.
Manager of Software Development
Westport Research Associates Inc.
7001 Blue Ridge Blvd
Raytown, MO 64133
(816) 358-8990
<a class="moz-txt-link-abbreviated" href="mailto:drboyd@westportresearch.com">drboyd@westportresearch.com</a>
/
On 03/09/2012 10:00 AM, Ruediger Meier wrote:
</pre>
<blockquote type="cite">
<pre wrap="">On Friday 09 March 2012, Boyd G. Gafford Ph.D. wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Just wanted to share these with the COD group here. I've been
running these rules for about a week now, and they have been
working wonderfully. Let me know if you end up using them and how
they work for you.
</pre>
</blockquote>
<pre wrap="">
Be aware that now it's easy for a attacker to make your servers
invisible for others by flooding your limit rules.
Maybe you should rather limit per ip.
cu,
Rudi
</pre>
<blockquote type="cite">
<pre wrap="">#!/bin/bash
# The main logic of ServerArk, all done with iptables!
# Version 1.01
# (C) 2012 Boyd G. Gafford Ph.D. (Usage is under the LGPL)
# To contact me, simply post on the forum at elitewarriors.net.
#
# Please note these rules ONLY affect UDP packets to the game
servers, nothing else!
# This script will protect all Q3-protocol servers on the port
28960. It protects
# against both 'getstatus' and 'getinfo' attacks, as well as
'getchallenge' atttacks,
# even from a UDP flood with random source IPs.
# Add a limit/drop chain for "getstatus" packets that limits it to
10 a second for all servers.
# If you are only protecting one server, you can set the number
from 10 down to 4 (or 2 even).
iptables -N LIMITSTAT
iptables -A LIMITSTAT -p udp -m limit --limit 10/sec --limit-burst
10 -j ACCEPT
iptables -A LIMITSTAT -p udp -j DROP
# Add a limit/drop chain for "getinfo" packets that limits it to
10 a second for all servers.
# If you are only protecting one server, you can set the number
from 10 down to 4 (or 2 even).
iptables -N LIMITINFO
iptables -A LIMITINFO -p udp -m limit --limit 10/sec --limit-burst
10 -j ACCEPT
iptables -A LIMITINFO -p udp -j DROP
# Add a limit/drop chain for "getchallenge" packets that limits it
to 5 a second for all servers.
# If you are only protecting one server, you can set the number
from 5 down to 2. Setting it
# at 2 means only 2 players could connect to the server per
second. Set LIMITCONN to the
# same, as there is one getchallenge/connect packet sequence per
valid player connection.
iptables -N LIMITCHLG
iptables -A LIMITCHLG -p udp -m limit --limit 5/sec --limit-burst
5 -j ACCEPT
iptables -A LIMITCHLG -p udp -j DROP
# Add a limit/drop chain for "connect" packets that limits it to 5
a second for all servers.
# If you are only protecting one server, you can set the number
from 5 down to 2. Setting it
# at 2 means only 2 players could connect to the server per
second. Set LIMITCHLG to the
# same, as there is one getchallenge/connect packet sequence per
valid player connection.
iptables -N LIMITCONN
iptables -A LIMITCONN -p udp -m limit --limit 5/sec --limit-burst
5 -j ACCEPT
iptables -A LIMITCONN -p udp -j DROP
# Add a limit chain that prevents more than 70 packets a second
per player. # This is the main logic of ServerArk, but just
performed by an iptable rule.
# We allow up to 128 players which is enough for 4 servers full
(at 32 players each).
# If you only have one server, you could the size and max to 32.
# If you have players who have manually set their packet rate up
to 100, just change the 70 to 100.
iptables -N LIMITPLRS
iptables -A LIMITPLRS -p udp -m hashlimit --hashlimit-name PLAYERS
--hashlimit-above 70/sec --hashlimit-burst 70 --hashlimit-mode
srcip,srcport --hashlimit-htable-size 128 --hashlimit-htable-max
128 --hashlimit-htable-gcinterval 1000 --hashlimit-htable-expire
10000 -j DROP iptables -A LIMITPLRS -p udp -j ACCEPT
# Add the rules to pick out the various special packets and send
them to appropriate limit chains.
# To protect 5 ports, just specify a range like "--dport
28960:28964" below. iptables -A INPUT -p udp --dport 28960-m
string --string "getstatus" --algo bm --from 32 --to 33 -j
LIMITSTAT
iptables -A INPUT -p udp --dport 28960-m string --string "getinfo"
--algo bm --from 32 --to 33 -j LIMITINFO
iptables -A INPUT -p udp --dport 28960-m string --string
"getchallenge" --algo bm --from 32 --to 33 -j LIMITCHLG
iptables -A INPUT -p udp --dport 28960-m string --string "connect"
--algo bm --from 32 --to 33 -j LIMITCONN
# Send all other packets (normal player packets) to the limit
players chain. # A port range like "--dport 28960:28964" could
also be used here as well. iptables -A INPUT -p udp --dport
28960-j LIMITPLRS /
/Also, you can do an "iptables -L -v -n" to see what kind of
attacks these rules have blocked. Here's an example of this
command after a "getchallenge" flood attack from random IPs, on
our Dallas server running on port 29070.
ew@server1:~$ sudo iptables -L -v -n
Chain INPUT (policy ACCEPT 11368 packets, 1538K bytes)
pkts bytes target prot opt in out source
destination
3880 177K LIMITSTAT udp -- * * 0.0.0.0/0
0.0.0.0/0 udp dpt:29070 STRING match "getstatus" ALGO
name bm FROM 32 TO 33
14036 617K LIMITINFO udp -- * * 0.0.0.0/0
0.0.0.0/0 udp dpt:29070 STRING match "getinfo" ALGO name
bm FROM 32 TO 33
37M 1620M LIMITCHLG udp -- * * 0.0.0.0/0
0.0.0.0/0 udp dpt:29070 STRING match "getchallenge" ALGO
name bm FROM 32 TO 33
17 4989 LIMITCONN udp -- * * 0.0.0.0/0
0.0.0.0/0 udp dpt:29070 STRING match "connect" ALGO name
bm FROM 32 TO 33
237K 17M LIMITPLRS udp -- * * 0.0.0.0/0
0.0.0.0/0 udp dpt:29070
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source
destination
Chain OUTPUT (policy ACCEPT 343K packets, 54M bytes)
pkts bytes target prot opt in out source
destination
Chain LIMITCHLG (1 references)
pkts bytes target prot opt in out source
destination
40025 1761K ACCEPT udp -- * * 0.0.0.0/0
0.0.0.0/0 limit: avg 5/sec burst 5
*37M 1618M DROP* udp -- * * 0.0.0.0/0
0.0.0.0/0
Chain LIMITCONN (1 references)
pkts bytes target prot opt in out source
destination
17 4989 ACCEPT udp -- * * 0.0.0.0/0
0.0.0.0/0 limit: avg 5/sec burst 5
0 0 DROP udp -- * * 0.0.0.0/0
0.0.0.0/0
Chain LIMITINFO (1 references)
pkts bytes target prot opt in out source
destination
14036 617K ACCEPT udp -- * * 0.0.0.0/0
0.0.0.0/0 limit: avg 10/sec burst 10
0 0 DROP udp -- * * 0.0.0.0/0
0.0.0.0/0
Chain LIMITPLRS (1 references)
pkts bytes target prot opt in out source
destination
1642 104K DROP udp -- * * 0.0.0.0/0
0.0.0.0/0 limit: above 70/sec burst 70 mode
srcip-srcport htable-size 128 htable-max 128
236K 17M ACCEPT udp -- * * 0.0.0.0/0
0.0.0.0/0
Chain LIMITSTAT (1 references)
pkts bytes target prot opt in out source
destination
3868 177K ACCEPT udp -- * * 0.0.0.0/0
0.0.0.0/0 limit: avg 10/sec burst 10
12 516 DROP udp -- * * 0.0.0.0/0
0.0.0.0/0
Notice the bolded packet/byte statistics for the "getchallenge"
drop chain named LIMITCHLG. A total of 37 million packets
dropped. I was on the game during this attack, and although the
server did lag a bit from the sheer size of the flood (almost
saturating the bandwidth), nobody lagged out. Without this rule,
the game server deadlocked.
Also notice you can tell how many players have connected to the
server, as the LIMITCONN status shows 17 packets accepted. So
during this time we had 17 players join the game.
You can also see how many people requested the servers in game (as
well as other services like GameTracker getting info on you), as
that corresponds to the LIMITSTAT and LIMITINFO chains.
Another cool thing you can do is "cat
/proc/srv/ipt_hashlimit/PLAYERS to see the IP addresses of all the
players currently connected to the server(s). Once a player quits
playing, he goes out of this file automatically after 10 seconds.
I may refine these a bit further, but for now, these seem to be
working well on our VPS.
Thanks,
/Boyd/
</pre>
</blockquote>
<pre wrap="">
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</pre>
</blockquote>
</blockquote>
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</pre>
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