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RE: Blackholes and IXs and Completing the Attack.

  • From: Tomas L. Byrnes
  • Date: Sat Feb 02 15:44:06 2008

You could achieve the exact same result simply by not advertising the
network to your peers, or by advertising a bogus route (prefixing a
known bogon AS for the addresses you want null-routed). I realize you
would have to subnet/deaggregate your netblocks, and therefore could
wind up with a prefix-length issue for peers who won't accept routes
longer than a certain mask, in some cases, but if you are already being
DDOSed, this should represent SOME improvement.

If you're trying to do it on a /32 basis, I doubt you'd find too many
border router operators interested in accepting a route that small, but
I may be wrong.

The bigger issue with all these approaches is that they run afoul of a
patent applied for by AT&T:

USPTO App Number 20060031575 

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On 
> Behalf Of Ben Butler
> Sent: Saturday, February 02, 2008 12:17 PM
> To: Paul Vixie; [email protected]
> Subject: RE: Blackholes and IXs and Completing the Attack.
> Hi,
> I was not proposing he Null routing of the attack source in 
> the other ISPs network but the destination in my network 
> being Null routed as a destination from your network out.
> This has no danger to the other network as it is my network 
> that is going to be my IP space that is blackholed in your 
> network, and the space blackholed is going to be an address 
> that is being knocked of the air anyway under DoS and we are 
> trying to minimise collateral damage.  I cant see where the 
> risk to the large NSP is - given that the route reflector 
> will only reflect /32s that legitimately originate (as a 
> destination not a source) in the AS announcing them as please 
> blackhole.
> For complete clarity: AS13005 announces and 
> has its route object in RIPE as being announced by AS13005.  
> My router at IX - BENIX say - announces to 
> the router reflector their, the announcement from my IX 
> assigned address is known to be my router on 
> the exchange, and I am announcing a /32 from my AS for a 
> route object registered as being announced by my AS - so the 
> reflector accepts my announcement and reflects it to any 
> other members that choose to peer with this reflector - 
> effectively this is a please blackhole this destination in 
> AS13005 - the other members that receive this announcement 
> can then deal with it in anyway they see fit from ignoring it 
> to setting next-hop -> Null0.
> The effect of this would be that any BotNet controlled hosts 
> in the other member network would now be able to drop any 
> attack traffic in their network on destination at their 
> customer aggregation routers.
> I think you might have thought I was suggesting we blackhole 
> sources in other peoples networks - this is definatly not 
> what I was saying.
> So, given we all now understand each other - why is no one 
> doing the above?
> At the end of the day if an IX member doesn't want the 
> announcements don't peer with the blackhole reflector, 
> simple, and it will get Null routed as soon as it hits my 
> edge router at the IX - it would just seem more sensible to 
> enable people to block the traffic before it traverses the IX 
> and further back in their own networks.
> So?????
> Ben
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On 
> Behalf Of Paul Vixie
> Sent: 02 February 2008 17:32
> To: [email protected]
> Subject: Re: Blackholes and IXs and Completing the Attack.
> [email protected] ("Ben Butler") writes:
> > ...
> > This hopefully will ensure a relatively protected router 
> that is only 
> > accessible from the edge routers we want and also secured to only 
> > accept filtered announcements for black holing and in consequence 
> > enable the system to be trusted similar to Team Cymaru.
> > ...
> This sounds like another attempt to separate the Internet's 
> control plane from its data plane, and most such attempts do 
> succeed and are helpful (like NSP OOB, or like 
> enterprise-level anycast of DNS).
> However, I'm not sure that remote triggered blackholes are a 
> good direction, worthy of the protection you're proposing, 
> for three reasons.
> First, because large NSP's simply cannot afford the risk 
> associated with letting a third party, automatically and 
> without controls or audits, decide in real time what sources 
> or destinations shall become unreachable.  With all respect 
> (which is a lot) for spamhaus and cymru and even MAPS (which 
> I had a hand in, back in the day), feeding BGP null-routes to 
> a multinational backbone is a privilege that ISO9000 and 
> SarBox and liability insurance providers don't usually want to extend.
> Second, because many backbone routers in use today can't do 
> policy routing routing (which is in this case dropping 
> packets because their source address, not their destination 
> address, has a particular community associated with it) at 
> line speed.  Note, this is many-not-all
> -- I'm perfectly aware that lots of backbone routers can do 
> this but not everybody has them or can afford them and those 
> who have them tend to be the multinational NSPs discussed earlier.
> To prevent our DDoS protection reflexes from lowering an 
> attacker's cost (by automatically blackholing victims to 
> protect the nonvictims), we have to be able to blackhole the 
> abusive traffic by source, not by destination.
> Third, because many OPNs (other people's networks) still 
> don't filter on source address on their customer-facing edge, 
> and thus allow spoofed-source traffic to exit toward "the 
> core" or toward a victim's NSP who cannot filter by source 
> due to path ambiguities inherent in "the core", any wide 
> scale implementation of this, even if we could get trusted 
> automation of it at scale and even if everybody had 
> policy-routing-at-like-speed, would just push the attackers 
> toward spoofed-source.  That means a huge amount of work and 
> money for the world, without changing the endgame for 
> attackers and victims at all.
> (See BCP38 and SAC004 for prior rants on this controversial topic.)