Using Policy Routing to stop DoS attacks

Fri Mar 28 14:47:16 UTC 2003

Andre,
	Actually it already exists.  But to do it, you need
to ensure you have loose-RPF checking enabled and null-route
the network you want the data dropped for.  Since a null-route
is considered by loose-RPF checking as a "bad" route, it will
drop the data for you.

thanks,
charles


On Fri, Mar 28, 2003 at 03:08:44PM +0100, Andre Chapuis wrote:
> 
> We could ask Cisco and Juniper to add a way of 'artificially' remove networks from the CEF table (with an ACL or so). That way, even with loose-RPF, the packet will be dropped based on source-address at the ingress without consuming CPU.
> Or maybe such a feature already exist
> André
> 
> At 09:06 25.03.2003 -0500, Christian Liendo wrote:
> 
> >Looking for advice.
> >
> >I am sorry if this was discussed before, but I cannot seem to find this.
> >I want to use source routing as a way to stop a DoS rather than use access-lists.
> >
> >In other words, lets say I know the source IP (range of IPs) of an attack and they do not change.
> >
> >If the destination stays the same I can easily null route the destination, but what if the destination constantly changes. So I have to work based on the source IP.
> >
> >Depending on the router and the code, if I implement an access-list then the CPU utilization shoots through the roof.
> >What I would like to try and do is use source routing to route that traffic to null. I figured it would be easier on the router than an access-list.
> >
> >Has anyone else tried this successfully on ciscos and junipers?
> >Is it easier on the CPU than access-lists?
> >Is there a link I cannot find on cisco or google?
> >
> >Thanks
> >Christian Liendo
> >
> 
> ---------------------
> Andre Chapuis
> IP+ Engineering
> Swisscom Ltd
> Genfergasse 14
> 3050 Bern
> +41 31 893 89 61
> chapuis at ip-plus.net
> CCIE #6023
> ----------------------
>