Strange network thing

[Ben Duncan]

Hmmm .. could it be udev is doing something ?

Have run into that cloning disk drives on identical machine. Turns out
I am using udev (which all in all is pretty neat), and the entries
where getting fixed.

See if you have a directory  called /etc/udev/rules.d
See if there is something in it like network-devices.rules.
You might have to fgrep for eth in the files to find it since udev
rules can be automagically generated.

In the network file you might something like this:


# Local network rules to name your network cards.
#
# These rules were generated by nethelper.sh, but you can
# customize them.
#
# You may edit them as needed.
# (If, for example, your machine has more than one network
# card and you need to be sure they will always be given
# the same name, like eth0, based on the MAC address)
#
# If you delete this file, /lib/udev/nethelper.sh will try to
# generate it again the next time udev is started.

KERNEL=="eth?", ATTR{address}=="00:1b:b9:d9:c8:da", NAME="eth0"
KERNEL=="eth?", ATTR{address}=="00:2b:29:29:d1:ab", NAME="eth1"

These are going to set the ethernet cards as defined based upon MAC
address.

In my case, all the CLONED hard disks machines where ALWAYS using eth1
instead of etho. After deleting the first line, and changing the second
everything worked as it should ...

As usual your mileage may vary ....





> Answering Lonni's questions, both the original IP and the new one are
> fixed, and if I ping this IP with the system down or the network
> interface down, no response.
> 
> As the NIC comes up fine when it's the only thing on the network, I have
> to assume that it is finding something that tells it the IP is taken.
> If that was the local ARP cache (for instance), that wouldn't make a
> difference.  Querying ARP on the other hosts in the subnet, and on the
> firewall appliance, I don't find anything--same for looking in the
> configuration on the switch it plugs into.
> 
> Actually, when I changed the IP, I changed the gateway address but
> probably not the actual gateway.  The network port was moved into a
> different VLAN.  But the problem started not with that but when I
> disabled the unused second NIC in the OS.  When I did that, the NIC that
> came up with the active configuration was in fact the one originally
> designated the second one.  That meant the IP was on a different MAC
> address, and appparently something it is querying when it tries to load
> "remembers" the old MAC the IP was associated with.
> 
> What I've been looking for is a diagnostic that would identify where
> it's happening.
> 
> 
> Stuart Biggerstaff
> Systems Technician
> Linda Hall Library of Science Engineering & Technology
> 5109 Cherry St.
> Kansas City, Missouri 64110-2498

-- 
Ben Duncan - Business Network Solutions, Inc. 336 Elton Road  Jackson MS, 39212
"Never attribute to malice, that which can be adequately explained by stupidity"
        - Hanlon's Razor