Re: SMURF amplifier block list

["Forrest W. Christian" <forrestc () iMach com>]

On Mon, 13 Apr 1998, Vadim Antonov wrote:

>  Uh.  Just modify BGP routes from that feed to have a next hop pointing
>  to a black hole.  route-maps are sometimes useful.

Could someone PLEASE explain to me how this is accomplished?

Let's assume that you do use a route-map to set next hop to a null
interface or a black hole or something for a prefix.  AND set local pref
appropriately so that route gets preferred.

You now have a routing entry which essentially says:

  "forward packets DESTINED FOR the evil network to the black hole".

What you really want is a routing entry which says:

  "forward packets FROM the evil network to the black hole".

Now, if someone could enlighten me to a way which you can get BGP to make
a routing/filter entry to do this second one, I'd be most grateful.

BTW, I know you can do this with PERL or config scripts or whatever.   The
point is that I don't think that a RBL-like blackhole feed will fix a
smurf attack from the "attacked" perspective, unless I have missed some
knob somewhere.

- Forrest W. Christian (forrestc () imach com) 
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