[cod] CoD2 UDP flood

Thu Feb 23 09:20:28 EST 2012

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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>>>
>>
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