Where are static bogon filters appropriate? was: 96.2.0.0/16 Bogons

Sun Mar 4 20:48:03 UTC 2007

On 3/2/07, Roland Dobbins <rdobbins at cisco.com> wrote:
> No one has done the digging required to answer any of these
> questions, unfortunately.

Can you get a valid answer to this based on the existence of BCP38?
What I mean is, if your upstream is filtering bogons, you can't get a
good read on the amount of "bad" traffic sourcing from "illegal"
addresses.  However, I'm sure it's there.  If we stop filtering
so-called "bad" addresses, I'm sure that the attacks from those
addresses will increase when it's realized that the filters are gone.

I agree with others in that you can't stop looking for old attacks
just because they don't happen much anymore.  But we can improve the
ways we look.  uRPF is definitely a dynamic option, but as I
understood it, there were issues with using it on multi-homed networks
with asynchronous routing.  Granted, it has been some time since I've
looked at uRPF.

I think something like the Cymru bogon route server is great, but I'm
not a very trusting person when it comes to something like that.  I
don't like giving up that level of control.  Of course, at some point,
I suppose have to trust something...

I definitely believe in filtering both bogons and RFC 1918 space, it's
just a management issue that has to be dealt with.

> -----------------------------------------------------------------------
> Roland Dobbins <rdobbins at cisco.com> // 408.527.6376 voice

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Jason 'XenoPhage' Frisvold
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http://blog.godshell.com