Re: Filtering Source Addresses on gw-internet

[Greg Ketell <gketell () cisco com>]

Sorry for the delay.  I am in all-day meetings through the end
of the week.

If Null0 were a standard interface I would say "yes, definitely
a better method".  But since it isn't, I am not sure.  I will
try to find out and post tomorrow night (unless someone else
from cisco (or formerly from cisco) pops up the answer first.

GK

> Date: Wed, 13 Aug 1997 06:46:58 -0400 (EDT)
> From: "C. Jon Larsen" <jlarsen () ajtech com>
> To: Greg Ketell <gketell () cisco com>
> cc: nanog () merit edu
> Subject: Re: Filtering Source Addresses on gw-internet
>
> Much thanks to everyone for their input. Greg, since you have
"Cisco" in your 
> email address, any comment on whether sending packets to a null
interface is a
> quicker / more efficient way blocking unwanted traffic ?
gw-internet is a
> little old 68030, with 1MB RAM.
>
> > -----BEGIN PGP SIGNED MESSAGE-----
> >
> > At 03:05 PM 8/12/97 -0400, C. Jon Larsen wrote:
> > > gw-internet#show access-lists 120
> > > Extended IP access list 120
> > >    deny   ip any 10.0.0.0 0.255.255.255 log
> > >    deny   ip any 172.16.0.0 0.0.255.255 log
> > >    deny   ip any 172.17.0.0 0.0.255.255 log
> > >    deny   ip any 192.168.0.0 0.0.255.255 log
> > >    permit ip a.b.c.0 0.0.0.255 any (27429 matches)
> > >    deny   ip any any log
> >
> > Line 2 and 3 could be replaced by
> > deny ip any 172.16.0.0 0.15.255.255 log
> >
> > which would block all 172.16.0.0-172.31.0.0 as per the RFC.
> >
> > You might also want to block 127.0.0.0.
> >
> > GK
> >
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>
> Linux.
>
> +-------------------+---------------------+
> | C. Jon Larsen     | jlarsen () ajtech com  |
> | Systems Engineer  | Tel: 804.353.2800   |
> | A&J Technologies  |                     |
> |-------------------+---------------------|
> |         http://www.ajtech.com           |
> +-----------------------------------------+