Re: Using Policy Routing to stop DoS attacks

[Andre Chapuis <chapuis () ip-plus net>]

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

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Andre Chapuis
IP+ Engineering
Swisscom Ltd
Genfergasse 14
3050 Bern
+41 31 893 89 61
chapuis () ip-plus net
CCIE #6023
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