[149198] in North American Network Operators' Group
Re: ARP is sourced from loopback address
daemon@ATHENA.MIT.EDU (William Herrin)
Mon Jan 30 19:10:25 2012
In-Reply-To: <4F2726AA.6060701@ttec.com>
From: William Herrin <bill@herrin.us>
Date: Mon, 30 Jan 2012 19:09:36 -0500
To: Joe Maimon <jmaimon@ttec.com>
Cc: NANOG <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Mon, Jan 30, 2012 at 6:24 PM, Joe Maimon <jmaimon@ttec.com> wrote:
> Golden.
> Thank you, William.
Hi Joe,
You're welcome. The flip side of Linux's arp funkiness is that you can
get it to do some nifty stuff. For example, a /32 ethernet looks more
or less like this:
ifconfig lo:1 198.51.100.1 netmask 255.255.255.255
ifconfig eth1 192.168.0.1 netmask 255.255.255.252
ip route add 198.51.100.44/32 dev eth1 src 198.51.100.1
arptables --out-interface eth1 -j mangle -s 192.168.0.1 --mangle-ip-s
198.51.100.1
The implicit proxy arp takes care of the rest with the machine hanging
off the interface thinking that it's part of a /24.
This sort of thing is how I'm using all 17 of the IP addresses in my
Cox /28. :-)
Regards,
Bill Herrin
--=20
William D. Herrin ................ herrin@dirtside.com=A0 bill@herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004
