Over a decade of DDOS--any progress yet?

David Ulevitch david at ulevitch.com
Mon Dec 6 09:34:13 CST 2010


On Mon, Dec 6, 2010 at 6:10 AM, Patrick W. Gilmore <patrick at ianai.net> wrote:
> On Dec 6, 2010, at 4:07 AM, Jonas Frey (Probe Networks) wrote:
>
>> Besides having *alot* of bandwidth theres not really much you can do to
>> mitigate. Once you have the bandwidth you can filter (w/good hardware).
>> Even if you go for 802.3ba with 40/100 Gbps...you'll need alot of pipes.
>
> There is a variation on that theme.  Using a distributed architecture (anycast, CDN, whatever), you can limit the attack to certain nodes.  If you have 20 nodes and get attacked from a botnet China, only the users on the same node as the Chinese use will be down.  The other 95% of your users will be fine.  This is true even if you have 1 Gbps per node, and the attack is 100 Gbps strong.

I think this is only true if you run your BGP session on a different
path (or have your provider pin down a static route).  If you are
using BGP and run it on the same path, the 100Gbps will cause massive
packet loss and likely cause your BGP session to drop which will just
move the attack to another site, rinse / repeat.  I don't think very
many people run BGP over a separate circuit, but for some folks, it
might be appropriate.

I also recommend folks anycast with a /22 or /23 and then use BGP for
the /23 or /24 announcements and have their provider pin down the /22
at a few sites so that if all hell breaks loose and the /23 or /24 is
flapping and being dampened then you still have reachability with the
covering prefix.  It also lets you harden and strengthen a few smaller
sites that have the /22 statically pinned down.  I'm not sure if
people think the "cost" of doing this is worth it, jury still out for
us.

But as you and others have pointed out, not a lot of defense against
DDoS these days besides horsepower and anycast. :-)

-David




More information about the NANOG mailing list