RE: UUNet Offer New Protection Against DDoS

Oh, and I strip their communities, and apply no-export, on the first
term of my route map so the /32 does not get out. Of course my peer
facing policy requires specific communities to get out as well (belt and

This method works very well, and you do not have to give up length
restrictions or maintain two sets of customer prefix/access lists.


From: Lumenello, Jason
Sent: Wednesday, March 03, 2004 4:52 PM
To: 'Stephen J. Wilcox'; james
Subject: RE: UUNet Offer New Protection Against DDoS

I struggled with this, and came up with the following.

We basically use a standard route-map for all customers where the


term looks for the community. The customer also has a prefix-list on


neighbor statement allowing their blocks le /32. The following terms


2 and above) in the route-map which do NOT look for the customer


community, have a different standard/generic prefix-list evaluation


blocks cruft and permits ge 8 le 24.

By doing this, I only accept a customer /32 from his dedicated


when it has the DOS discard community, otherwise I catch them with the


8 le 24 in the following terms.

Jason Lumenello
IP Engineering
XO Communications

> From: [] On Behalf


> Stephen J. Wilcox
> Sent: Wednesday, March 03, 2004 3:48 PM
> To: james
> Cc:
> Subject: Re: UUNet Offer New Protection Against DDoS
> I'm puzzled by one aspect on the implementation.. how to build your
> customer
> prefix filters.. that is, we have prefix-lists for prefix and


> Therefore
> at present we can only accept a tagged route for a whole block.. not
> if the
> announcement is a /16 etc !
> Now, I could do as per the website at which means we have


> route-map
> entry to match the community before the filtering .. but that would
> the
> customer to null route any ip.
> What we need is one to allow them to announce any route including


We actually accept up to the customers aggregate. So if they have a /16, they can tag the whole /16. And we do not tag no-export. I saw some time ago on a list, and I think Bill Manning suggested it, that if you are getting bits for unused address space, to announce that address space (up to host specific) with the DDoS community string. That keeps the packets off of your link and thus you don’t get charged for them. The same can be done in reverse. We have a customer that is advertising their larger block with the DDoS community string, and then advertising the addresses they are actually using more specifically, so we blackhole everything less specific. These are a couple of applications that can be utilized if you don’t tag no-export and accept more than just /32’s within their address space. FWIW.

Also, we are utilizing Juniper’s DCU for tracebacks, which makes life MUCH easier when tracing an attack. :slight_smile: SNMP polling the DCU counters every few minutes is relatively fast and painless, and provides quick results.


Lumenello, Jason wrote: