[cod] CoD2 UDP flood

Thu Feb 23 10:16:28 EST 2012

Did the trick. Thanks! =)

On Thu, Feb 23, 2012 at 10:14 AM, Marco Padovan <evcz at evcz.tk> wrote:

>  iptables --flush ; iptables --delete-chain
>
> that will completly empty your firewall...
>
> then run your script
>
> Il 23/02/2012 16:06, escapedturkey ha scritto:
>
> iptables --flush
>
>  /sbin/iptables -N QUERY-BLOCK
>  iptables: Chain already exists.
>
>  /sbin/iptables -N QUERY-CHECK
> iptables: Chain already exists.
>
>  Any help? =)
>
>
> On Thu, Feb 23, 2012 at 10:03 AM, Marco Padovan <evcz at evcz.tk> wrote:
>
>>  The
>>
>> "Chain already exists." error should appear...
>>
>> iptables --flush
>>
>> then run the script...
>>
>> eventually run all the rules one by one and see which one is giving you
>> the error...
>>
>> you can monitor the number of blocked packets issuing:
>>
>> iptables -nvx -L QUERY-BLOCK
>>
>> and
>>
>> iptables -nvx -L QUERY-CHECK
>>
>> Il 23/02/2012 15:53, escapedturkey ha scritto:
>>
>> # 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.
>> /sbin/iptables -N QUERY-BLOCK
>> /sbin/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.
>> /sbin/iptables -N QUERY-CHECK
>> /sbin/iptables -A QUERY-CHECK -p udp -m string ! --string "getstatus"
>> --algo bm --from 32 --to 41 -j RETURN
>> /sbin/iptables -A QUERY-CHECK -p udp --sport 0:1025 -j DROP
>> /sbin/iptables -A QUERY-CHECK -p udp --sport 3074 -j DROP
>> /sbin/iptables -A QUERY-CHECK -p udp --sport 7777 -j DROP
>> /sbin/iptables -A QUERY-CHECK -p udp --sport 27015:27100 -j DROP
>> /sbin/iptables -A QUERY-CHECK -p udp --sport 25200 -j DROP
>> /sbin/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.
>> /sbin/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.
>> # /sbin/iptables -A QUERY-CHECK -m hashlimit --hashlimit-mode srcip
>> --hashlimit-name getstatus --hashlimit-above 2/second -j QUERY-BLOCK
>> # CentOS 5 or CentOS 6 compatible
>> /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
>> # look at all the packets going to q3/cod*/et/etc servers
>> # /sbin/iptables -A INPUT -p udp --dport 27960:29000 -j QUERY-CHECK
>> /sbin/iptables -A INPUT -p udp --dport 27000:30000 -j QUERY-CHECK
>>
>>  ./spamblock.bsh
>> iptables: Chain already exists.
>> iptables: Chain already exists.
>>
>>  iptables -L -n
>> Chain INPUT (policy ACCEPT)
>> target prot opt source destination
>> QUERY-CHECK udp -- 0.0.0.0/0 0.0.0.0/0 udp dpts:27000:30000
>>
>> Chain FORWARD (policy ACCEPT)
>> target prot opt source destination
>>
>> Chain OUTPUT (policy ACCEPT)
>> target prot opt source destination
>>
>> Chain QUERY-BLOCK (1 references)
>> target prot opt source destination
>> DROP all -- 0.0.0.0/0 0.0.0.0/0 recent: SET name: blocked-hosts side:
>> source
>>
>> Chain QUERY-CHECK (1 references)
>> target prot opt source destination
>> RETURN udp -- 0.0.0.0/0 0.0.0.0/0 STRING match !"getstatus" ALGO name bm
>> FROM 32 TO 41
>> DROP udp -- 0.0.0.0/0 0.0.0.0/0 udp spts:0:1025
>> DROP udp -- 0.0.0.0/0 0.0.0.0/0 udp spt:3074
>> DROP udp -- 0.0.0.0/0 0.0.0.0/0 udp spt:7777
>> DROP udp -- 0.0.0.0/0 0.0.0.0/0 udp spts:27015:27100
>> DROP udp -- 0.0.0.0/0 0.0.0.0/0 udp spt:25200
>> DROP udp -- 0.0.0.0/0 0.0.0.0/0 udp spt:25565
>> DROP all -- 0.0.0.0/0 0.0.0.0/0 recent: UPDATE seconds: 30 hit_count: 1
>> name: blocked-hosts side: source
>> RETURN all -- 0.0.0.0/0 0.0.0.0/0 limit: up to 2/sec burst 5 mode srcip
>> QUERY-BLOCK all -- 0.0.0.0/0 0.0.0.0/0
>>
>>  Should I be concerned with " iptables: Chain already exists."?
>>
>>
>> On Thu, Feb 23, 2012 at 9:44 AM, Marco Padovan <evcz at evcz.tk> wrote:
>>
>>>  sure, do it :)
>>>
>>> Il 23/02/2012 15:44, escapedturkey ha scritto:
>>>
>>> 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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>>>>>>>
>>>>>>>
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>>>>>>>
>>>>>>
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