[cod] Hey everyone

Thu Feb 23 18:15:20 EST 2012

Yep, thats getting towards the saturated side lol.  It must be a 
distributed DOS UDP flood, as I can't imagine many script kiddies with 
that kind of bandwidth for a single attack spoofing 20 IPs.

At that point, a lot of your CPU is just handling the incoming IP 
packets.  Not much to do in that situation.  Even if you bonded four 
GbE's together, you're still looking at needing quite a chunk of CPU 
just to offload throwing away that 1Gbps.

Even if you were to dynamically interact with your router to tell it to 
drop the packets, your incoming bandwidth would still be hammered.  It 
almost has to happen at the carrier (preferably at the carriers of the 
flooders) to do anything to help, and we all know how likely that is to 
happen unfortunately.

Good luck,

/Boyd/

On 02/23/2012 04:46 PM, NewLight Systems wrote:
> The problem is that we are receiving for example 1 GBPS attacks to one 
> IP from serveral sources ( maybe 15 - 20 ips )
>
> That means that 1 GB of inbound is occupied. We have iptables rules, 
> of course, but is affecting all services on that dedicated server
>
> El 23/02/12 23:42, Boyd G. Gafford Ph.D. escribió:
>> Hey there, thanks for responding.
>>
>> I'm not sure I understand what you mean by "the line is occupied 
>> anyway."  If you mean the bandwidth to the server is saturated by the 
>> flood, then yeah, its going to affect game play.  Fortunately most 
>> servers at data centers have high enough bandwidth to them that a 
>> typical attack doesn't saturate.
>>
>> If your game server port is the target of a single IP UDP flood 
>> attack, then typically an iptables drop rule handled by the kernel is 
>> more efficient than the game server itself, especially if the flooded 
>> packets are server commands that are being processed by the game 
>> server, which is sending out UDP reply packets.  That takes up much 
>> more CPU than a kernel-level packet drop.
>>
>> Under those circumstances, the cheap VPS we use in Dallas has endured 
>> 64Mbps attacks for hours and the game server is still very playable.  
>> It would be nice if the flood was blocked at the router or carrier 
>> level, but still iptables is pretty amazing when the kernel drop is 
>> your last line of defense.
>>
>> Thanks,
>>
>> /Boyd/
>>
>>
>> On 02/23/2012 04:22 PM, NewLight Systems wrote:
>>> It's ok but this isn't working if the UDP floods to your server 
>>> because the line is occupied anyway.
>>>
>>> If you are the target, there's nothing you can do in a dedicated 
>>> server level.
>>>
>>> This type of attack ( allways if you are the target ) have to be 
>>> erradicated in a higher level ( router or carrier ) if you want to 
>>> preserve your connection
>>>
>>> El 23/02/12 23:12, Boyd G. Gafford Ph.D. escribió:
>>>> Hey everyone, EscapedTurkey told me about this group, and so I Just 
>>>> wanted to say a quick hello.
>>>>
>>>> I'm the guy who got frustrated enough with UDP flood attacks that I 
>>>> wrote ServerArk to deal with the majority of them.  If anyone has 
>>>> any questions about the program, or any ideas on what they would 
>>>> like to see in it in the future, by all means let me know.
>>>>
>>>> Since I've been using it on our JA (Q3 protocol) servers 
>>>> (http://elitewarriors.net) its blocked about 20 high volume attacks 
>>>> (one at 64Mbps) successfully over the past few months.  As long as 
>>>> the source IP of the UDP flood is not random, it works really well.
>>>>
>>>> I have a few new ideas on flood detection on random IP attacks I 
>>>> will ping off your guys over the next few days to see what you think.
>>>>
>>>> Also kudos to whoever did the "I don't want to participate in 
>>>> reflection attacks" iptables rule that matches off of the 
>>>> 'getstatus' UDP packet payload.  If everyone who had a Q3 protocol 
>>>> server (COD, JA, etc) had that rule running reflection attacks 
>>>> would be a LOT less potent.
>>>>
>>>> :)
>>>>
>>>> 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
>>>> drboyd at westportresearch.com
>>>> /
>>>>
>>>>
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>>>> cod at icculus.org
>>>> http://icculus.org/mailman/listinfo/cod
>>>
>>> -- 
>>>
>>>
>>> *David Aguilar Valero*
>>>
>>> Dpto. Comercial y Soporte técnico
>>>
>>> NewLight Systems
>>>
>>> *Servidores de juegos, HW, Dedicados*
>>>
>>>
>>> *crk01 at nls.es* <mailto:c>
>>>
>>> crk01 at newlightsystems.com <mailto:crk01 at newlightsystems.com>
>>>
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>>>
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>>>
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> -- 
>
>
> *David Aguilar Valero*
>
> Dpto. Comercial y Soporte técnico
>
> NewLight Systems
>
> *Servidores de juegos, HW, Dedicados*
>
>
> *crk01 at nls.es* <mailto:c>
>
> crk01 at newlightsystems.com <mailto:crk01 at newlightsystems.com>
>
> tecnico at newlightsystems.com <mailto:tecnico at newlightsystems.com>
>
> #NewLight_Systems @ irc-hispano.org
>
> *www.newlightsystems.com* <http://www.newlightsystems.com/>
>
> *www.nls.es* <http://www.nls.es/>
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