Network Operators and smurf

Jay R. Ashworth jra at
Fri Apr 24 22:55:53 UTC 1998

On Fri, Apr 24, 1998 at 06:39:28PM -0400, Dean Anderson wrote:
> >Dean, but I'd be happy to be proven wrong.
> There isn't a simple knob, but then it isn't simple to know what a forgery
> is. You to have tell the router.  The router doesn't know what you and
> other people "own", but you can tell it.  I'd say there isn't a way to make
> a simple on/off knob for that, because there isn't any way to tell who you
> will transit for and who you won't.
> Or, another perhaps better way is to only accept packets from your customer
> networks which are sourced from those networks.  Each customer interface
> then has an inbound filter the blocks everything not sourced from your
> customers network.

That was the idea.  I was, as noted, mostly talking about router
interfaces with only one network (block) behind it.  I gather a large
part of it comes from dialups, where the remote network is a /32.

in any event, I'm not sure I made the query explicit enough, from a
couple of replies I got: the knob I'm specifically interested in says
"don't forward packets with source addresses that can't be routed back
out this port".

-- jra
Jay R. Ashworth                                                jra at
Member of the Technical Staff             Unsolicited Commercial Emailers Sued
The Suncoast Freenet      "Two words: Darth Doogie."  -- Jason Colby,
Tampa Bay, Florida             on             +1 813 790 7592

Managing Editor, Top Of The Key sports e-zine ------------

More information about the NANOG mailing list