[cod] CoD2 UDP flood

[escapedturkey]

iptables v1.4.7: Couldn't load target
`QUERY-BLOCK':/lib64/xtables/libipt_QUERY-BLOCK.so: cannot open shared
object file: No such file or directory

Any ideas?


On Wed, Feb 22, 2012 at 4:51 PM, Marco Padovan <evcz at evcz.tk> wrote:

>  on centos5 and centos6
>
> modifying this line:
> iptables -A QUERY-CHECK -m hashlimit --hashlimit-mode srcip
> --hashlimit-name getstatus --hashlimit-above 2/second -j QUERY-BLOCK
>
> in this way (two different lines):
> iptables -A QUERY-CHECK -m hashlimit --hashlimit-mode srcip
> --hashlimit-name getstatus --hashlimit 2/s -j RETURN
> iptables -A QUERY-CHECK -j QUERY-BLOCK
>
> should mimic the same behaviour
>
> Il 22/02/2012 18:43, Geoff Goas ha scritto:
>
> Hi,
>
> On CentOS 5.5, *--hashlimit-above* is not a valid option for the
> "hashlimit" match. Which version of iptables introduces this, and how can I
> mimic that same ruleset with the options available to me in version 1.3.5
> of iptables?
>
> Thanks,
>
> On Fri, Jan 20, 2012 at 7:51 PM, John <lists.cod at nuclearfallout.net>wrote:
>
>>  On 1/20/2012 3:27 PM, Marco Padovan wrote:
>>
>> I was referring to dynamic filtering using -m recent
>>
>>  [not] to manually adding IPs O.o
>>
>>
>> Marco's right about this. The most effective way to prevent effects from
>> these attacks on Linux is to use a combination of the "string",
>> "hashlimit", and "recent" modules. Done right, the solution is mostly
>> automatic, so you shouldn't need to manually add IPs.
>>
>> These commands, for instance, would block external IPs that send queries
>> at a rate of 2/second or higher:
>>
>> # add a host to the banlist and then drop the packet.
>> iptables -N QUERY-BLOCK
>> iptables -A QUERY-BLOCK -m recent --set --name blocked-hosts -j DROP
>>
>> # is this a query packet? if so, block commonly attacked ports outright,
>> # then see if it's a known attacking IP, then see if it is sending at a
>> high
>> # rate and should be added to the list of known attacking IPs.
>> iptables -N QUERY-CHECK
>> iptables -A QUERY-CHECK -p udp -m string ! --string "getstatus" --algo bm
>> --from 32 --to 41 -j RETURN
>> iptables -A QUERY-CHECK -p udp --sport 0:1025 -j DROP
>> iptables -A QUERY-CHECK -p udp --sport 3074 -j DROP
>> iptables -A QUERY-CHECK -p udp --sport 7777 -j DROP
>> iptables -A QUERY-CHECK -p udp --sport 27015:27100 -j DROP
>> iptables -A QUERY-CHECK -p udp --sport 25200 -j DROP
>> iptables -A QUERY-CHECK -p udp --sport 25565 -j DROP
>> # is it already blocked? continue blocking it and update the counter so it
>> # gets blocked for at least another 30 seconds.
>> iptables -A QUERY-CHECK -m recent --update --name blocked-hosts --seconds
>> 30 --hitcount 1 -j DROP
>> # check to see if it exceeds our rate threshold,
>> # and add it to the list if it does.
>> iptables -A QUERY-CHECK -m hashlimit --hashlimit-mode srcip
>> --hashlimit-name getstatus --hashlimit-above 2/second -j QUERY-BLOCK
>>
>> # look at all the packets going to q3/cod*/et/etc servers
>> iptables -A INPUT -p udp --dport 27960:29000 -j QUERY-CHECK
>>
>> The "recent" module makes it possible to block up to 100 IPs at once with
>> this method (any attackers beyond this would only be rate-limited). That
>> number can be raised when the module is loaded, but I haven't seen 100
>> attacks happening at once yet (typically it's maybe 5-20 at once). You can
>> see blocked hosts later by looking at /proc/net/xt_recent/blocked-hosts.
>>
>> (If you don't have "recent", you could get away without it -- just be
>> aware that some of the packets will get through, increasing load on the
>> game server. Without "hashlimit", you'd still see an advantage from the
>> port checks, but you'd need to manually block IPs that are being hit on
>> other ports. Without "string", you'd similarly be down to just port checks,
>> and need to take out the other rules.)
>>
>> -John
>>
>> _______________________________________________
>> cod mailing list
>> cod at icculus.org
>> http://icculus.org/mailman/listinfo/cod
>>
>>
>
>
> --
> *Geoff Goas
> Systems Engineer*
>
>
>
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