SYN floods (was: does history repeat itself?)
Alexis Rosen
alexis at panix.com
Tue Sep 10 18:07:03 UTC 1996
Alec H. Peterson writes:
>
> Pat Calhoun writes:
> > This is actually quite simple to implement on Dial Access Routers,
> > and obviously this is the best place to add the filtering.
>
> Sure, that's a place to start. Except for a few problems:
>
> 1) The people doing this are not necessarily using a dialup IP
> connection.
True. That's why you need to filter upstream of public-access unix boxes
(like our own).
> 2) Many of us don't have dial access routers that can handle this.
Also true. As I said before, I don't know about the Ascends, but I do know
that the Xylogics boxes we use have the capability but probably not the
capacity. When all ports are connected at 28.8, CPU usage can hover in
the high 80% range. Adding filters would probably be a bad idea.
That's why I was talking about filtering at a router just upstream from
the dial-access box.
FWIW, even with a thousand very busy modems, I'm pretty sure that even a
small cisco is up to the job. They just don't generate all that much traffic.
/a
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