[10800] in North American Network Operators' Group
Re: NSPs and filters (fwd)
daemon@ATHENA.MIT.EDU (Barney Wolff)
Mon Jul 14 15:00:59 1997
From: Barney Wolff <barney@databus.com>
To: nanog@merit.edu
Date: Mon, 14 Jul 1997 14:20 EDT
> Date: Mon, 14 Jul 1997 12:29:32 -0400
> From: Daniel Senie <dts@proteon.com>
>
> And it goes beyond that... Every PC running Windows (or any other OS,
> for that matter) has complete ability to do anything with IP. So, any
> user on a dialup line into any ISP is a possible source of attacks.
>
> This is why I think the RAS servers need to be able to filter right at
> the point of the dialup. There, the comparison is a simple compare of a
> 32 bit integer (IP address assigned to the dialup user, compared to the
> IP address of packets received from the user). Any discrepancies should
> set off alarm bells...
Some ISPs, including the very large one for which I wrote the PPP code,
already do this.
Source address assurance is the mirror image of destination-based routing.
That's not to say that routing is always symmetrical, but the problem
is no harder, and can be made no slower.
Barney Wolff <barney@databus.com>
