no ip forged-source-address

Wed Oct 30 19:08:26 UTC 2002

On Wed, Oct 30, 2002 at 08:02:13PM +0100, Lars Erik Gullerud wrote:
> 
> On Wed, 2002-10-30 at 16:44, variable at ednet.co.uk wrote:
> 
> > Therefore, would it be a reasonable suggestion to ask router vendors to
> > source address filtering in as an option[1] on the interface and then move
> > it to being the default setting[2] after a period of time?  This appeared
> > to have some success with reducing the number of networks that forwarded
> > broadcast packets (as with "no ip directed-broadcast").
> [snip] 
> 
> > [1] For example, an IOS config might be:
> > 
> > interface fastethernet 1/0
> >  no ip forged-source-address
> 
> Well, this already exists, doesn't it? Try the following on your
> customer-facing interface:
> 
> ip verify unicast source reachable-via rx
> 
> > [2] Network admins would still have the option of turning it off, but this 
> > would have to be explicitly configured.
> 
> I have a feeling that having strict uRPF as the default setting on an
> interface would be very badly received by a lot of ISP's. I know I
> certainly wouldn't like it very much.
> 
> Is it really the job of router vendors to protect the net from
> lazy/incompetent/ignorant network admins?

	No, but I can't enable these features on all
my router interfaces without causing delays/drops due to poor
inital design quality and lack of long-term vision for linecards
manufactured.

	The rush for time-to-market can cause you to lose in
the long-term due to lack of features.

	- jared

-- 
Jared Mauch  | pgp key available via finger from jared at puck.nether.net
clue++;      | http://puck.nether.net/~jared/  My statements are only mine.