[cod] CoD2 UDP flood

Thu Feb 23 09:44:00 EST 2012

I support most Q3 engine games. Some go beyond the range specified in the
original post.

Can I change:

iptables -A INPUT -p udp --dport 27960:29000 -j QUERY-CHECK

To:

iptables -A INPUT -p udp --dport 27000:30000 -j QUERY-CHECK

Or will that cause problems?

Ex: JK2 =28070 JA = 29070

On Thu, Feb 23, 2012 at 9:30 AM, Marco Padovan <evcz at evcz.tk> wrote:

>  Let us know if that works ;)
>
> Il 23/02/2012 15:20, escapedturkey ha scritto:
>
> Thank you. Much appreciated. =)
>
> On Thu, Feb 23, 2012 at 7:33 AM, Marco Padovan <evcz at evcz.tk> wrote:
>
>>  Ehm,
>> nope :D
>>
>> You need all the lines John posted:
>>
>> http://icculus.org/pipermail/cod/2012-January/015861.html
>>
>> To make it works in centos5 / 6 change into that ruleset:
>>
>> 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
>>
>>  all the other rules should be kept as they are :)
>>
>> Il 23/02/2012 13:10, escapedturkey ha scritto:
>>
>> Thank you. I missed those lines.
>>
>>  Here is what I have so far:
>>
>>  /sbin/iptables -N QUERY-BLOCK
>> /sbin/iptables -A QUERY-BLOCK -m recent --set --name blocked-hosts -j DROP
>> /sbin/iptables -A QUERY-CHECK -m hashlimit --hashlimit-mode srcip
>> --hashlimit-name getstatus --hashlimit 2/s -j RETURN
>> /sbin/iptables -A QUERY-CHECK -j QUERY-BLOCK
>>
>>  Is this correct?
>>
>>  Thank you again. =)
>>
>> On Thu, Feb 23, 2012 at 5:32 AM, Marco Padovan <evcz at evcz.tk> wrote:
>>
>>>  did you issued all the other commands?
>>>
>>> like:
>>>
>>>  iptables -N QUERY-BLOCK
>>> iptables -A QUERY-BLOCK -m recent --set --name blocked-hosts -j DROP
>>>
>>>  ?
>>>
>>> Il 23/02/2012 03:54, escapedturkey ha scritto:
>>>
>>> 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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