ARP is sourced from loopback address

William Herrin bill at herrin.us
Mon Jan 30 18:09:36 CST 2012


On Mon, Jan 30, 2012 at 6:24 PM, Joe Maimon <jmaimon at 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



-- 
William D. Herrin ................ herrin at dirtside.com  bill at herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004



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