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swapped motherboard - eth0 was changed to eth2
http://forum.linhes.org/viewtopic.php?f=2&t=15827		 Page 1 of 1
Author:  neutron68 [ Mon Jul 09, 2007 10:27 pm ]
Post subject:  swapped motherboard - eth0 was changed to eth2
Hi,

I was having troubles with my particular Asus A8N-VM CSM motherboard so I got another of the exact same model to replace it.

I left everything the same in the Knoppmyth R5F1 system and just changed the board out tonight. Before I let Knoppmyth boot, I flashed the BIOS up to the exact same revision as my first Asus board - to be sure all would be the same. I was also careful to put the cards back in the same slots as the first board. I have the BIOS set to enable plug and play mode. I had the previous board set that way and it was fine.

Before, the onboard ethernet adapter was eth0 and all the networking was set to use eth0. If I use "cat /proc/interrupts" the only network adpater that shows up is eth2. (see below)

So, on the first boot of Knoppmyth, the Knoppix boot routines were trying to connect to eth0 and could not. I have a static IP assigned to eth0 in the "/etc/network/interfaces" file.

Any idea what happened to eth0??

Is it possible for me to change the onboard ethernet adapter back to being eth0 or am I going to have to accept the eth2 and change all my networking settings to match up with eth2?

Eric

Code:
           CPU0
  0:    1054927    IO-APIC-edge  timer
  1:        424    IO-APIC-edge  i8042
  4:          9    IO-APIC-edge  lirc_serial
  6:          5    IO-APIC-edge  floppy
  7:          2    IO-APIC-edge  parport0
  8:          1    IO-APIC-edge  rtc
  9:          0   IO-APIC-level  acpi
 12:        375    IO-APIC-edge  i8042
 14:      21764    IO-APIC-edge  ide0
 15:      71417    IO-APIC-edge  ide1
 16:     102529   IO-APIC-level  ohci_hcd:usb2, eth2
 17:        130   IO-APIC-level  libata, HDA Intel
 18:          0   IO-APIC-level  libata
 19:          0   IO-APIC-level  ehci_hcd:usb1
 20:          0   IO-APIC-level  cx88[0], cx88[0]
 21:          2   IO-APIC-level  ohci1394
 22:      21905   IO-APIC-level  nvidia
NMI:          0
LOC:    1054938
ERR:          1
MIS:          0
Author:  neutron68 [ Tue Jul 10, 2007 8:07 am ]
Post subject:  it looks like udev did it to me
I think I see what is going on. Apparently, if udev sees a new ethernet inferface with a new mac address, it creates a new network adapter and increments the eth0 number.

With the help of a Knoppmyth forum post referenced below, I think I found the udev file that stores the mac address and the interface names.

It is the file: /etc/udev/rules.d/z25_persistent-net.rules

Here is my file as of this morning:

Code:
# This file was automatically generated by the /lib/udev/write_net_rules # program, probably run by the persistent-net-generator.rules rules file.
#
# You can modify it, as long as you keep each rule on a single line.
# MAC addresses must be written in lowercase.

# PCI device 0x10de:0x0269 (forcedeth)
SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:15:f2:5b:8f:8c", NAME="eth0"

# Firewire device 0011d800007cdf9e (ohci1394)
SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:11:d8:00:00:7c:df:9e", NAME="eth1"

# PCI device 0x10de:0x0269 (forcedeth)
SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:17:31:54:0c:a5", NAME="eth2"

# Firewire device 0011d8000091c1d4 (ohci1394)
SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:11:d8:00:00:91:c1:d4", NAME="eth3"


Here is the message I found the clue in:
http://mysettopbox.tv/phpBB2/viewtopic. ... dress+file

I think that all I need to do is edit the /etc/udev/rules.d/z25_persistent-net.rules file and delete the sections for eth0 and eth1, then rename eth2 and eth3 to eth0 and eth1 and reboot.

Additional:

YES! I was correct. :D
An edit of the /etc/udev/rules.d/z25_persistent-net.rules file as described above, corrected the problem. I'm back to my ethernet adapter being eth0 and my network access with static IP address works again. 8)

Eric
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