RE: Router stops routing after changing MAC Address

On eth0 - no. My "fudged" MAC Address is based on the IP Address.  So
1.2.3.50 becomes 001.002.003.050, which turns into 00:10:02:00:30:50.
But 1.2.3 is fake - it isn't the one I really use.  The other one,
172.16.16.3 - that is a real IP Address that turns into
17:20:16:01:60:03.  And here I thought I was pretty clever - it never
dawned on me in my wildest dreams that those bits had any special
meaning!  I will do some homework about what all the bits mean and then
put together another scheme for my fudged IP Addresses and post the
results here.

- Greg



-----Original Message-----
From: Chuck Ebbert [mailto:76306.1226@compuserve.com] 
Sent: Monday, March 13, 2006 12:11 AM
To: Greg Scott
Cc: linux-kernel; David S. Miller
Subject: Re: Router stops routing after changing MAC Address

In-Reply-To:
[off-list ref]

On Fri, 10 Mar 2006 18:33:15 -0600, Greg Scott wrote:

How to change MAC addresses is documented well enough - and it works -

but when I change MAC addresses, my router stops routing.  From the 
router, I can see the systems on both sides - but the router just 
refuses to forward packets.  Here are my little test scripts to change

MAC Addresses.

First - ip-fudge-mac.sh
[root@test-fw2 gregs]# more ip-fudge-mac.sh ip link set eth0 down ip 
link set eth0 address 01:02:03:04:05:06

                            ^
 Bit zero is set, so this is a multicast address.  Is that intentional?

ip link set eth0 up

ip link set eth1 down
ip link set eth1 address 17:20:16:01:60:03

                            ^
 Ditto.

ip link set eth1 up

echo "1" > /proc/sys/net/ipv4/ip_forward

--
Chuck
"Penguins don't come from next door, they come from the Antarctic!"