[SGVLUG] Random MAC address.

Tue May 29 12:42:59 PDT 2007

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Michael Proctor-Smith wrote:
> So I have been building this new server and have run into this issue
> where the mac address seems to be different every time the system
> reboots. Anyone seen this "feature" in new motherboards it is an
> Nforce based AMD dual core board. The even more fun part is the
> kudzu(centos 5 system) will see that the mac address has changes
> assume that the ethernet card has changed and create a new dhcp based
> network config (sense the mac address is different the system would be
> a different random ip address on every boot) even if you have put a
> static config in place. I disabled kudzu mostly salved that problem.
> 
> Anyone have suggestion the bios has a field to enter MAC address and
> that does not help. This only really matters because I would like to
> wakeonlan this box but sense its mac address seems to be random it
> seems almost imposable.
> 
> 

I have noticed that my NIC cards keep getting 'shuffled' when I reboot.

e.g. Sometimes the WAN NIC boots up as 'eth0', and sometimes it boots up
as 'eth1' instead.

I have multiple NICs installed, so it gets a bit annoying trying to
figure out which is which after rebooting.

My iptables/ip_forward (firewall/router) and dnsmasq
configuration-scripts assume that the WAN NIC is always 'eth0', so when
it switches to eth1, I have to physically modify and re-execute them.
*shrug*

This is obviously inefficient, as I sometimes need to reboot my system
remotely, which will cause my system to be exposed (w/ out firewall),
and may even prevent me from reconnecting to fix it (until I get home).

I'm using an Abit KN9 SLI board w/ an Athlon X2 3800+ CPU. I just
recently built this box and haven't rebooted more than a few times so it
hasn't become a big deal yet, but I would like to know how to fix this
before it gets any more annoying.

I wonder if this has something similar to do with what Michael's problem
is, perhaps the same (or similar) solution?

- --- before rebooting ---

eth0      Link encap:Ethernet  HWaddr 00:50:8D:95:C4:19
          inet addr:72.134.40.135  Bcast:255.255.255.255  Mask:255.255.240.0
          inet6 addr: fe80::250:8dff:fe95:c419/64 Scope:Link
          UP BROADCAST NOTRAILERS RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:6597009 errors:0 dropped:0 overruns:0 frame:0
          TX packets:293960 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:857380059 (817.6 Mb)  TX bytes:25505561 (24.3 Mb)
          Interrupt:16 Base address:0x6000

eth1      Link encap:Ethernet  HWaddr 00:50:8D:95:C4:1A
          inet addr:192.168.2.1  Bcast:192.168.2.255  Mask:255.255.255.0
          inet6 addr: fe80::250:8dff:fe95:c41a/64 Scope:Link
          UP BROADCAST NOTRAILERS RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:398095 errors:0 dropped:0 overruns:0 frame:0
          TX packets:463991 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:42833208 (40.8 Mb)  TX bytes:558036355 (532.1 Mb)
          Interrupt:17 Base address:0xc000

eth2      Link encap:Ethernet  HWaddr 00:02:E3:17:FF:88
          inet addr:10.100.1.0  Bcast:10.255.255.255  Mask:255.0.0.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
          Interrupt:20 Base address:0xe000

- --- after rebooting ---

eth0      Link encap:Ethernet  HWaddr 00:02:E3:17:FF:88
          inet addr:10.100.1.0  Bcast:10.255.255.255  Mask:255.0.0.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
          Interrupt:21 Base address:0x6000

eth1      Link encap:Ethernet  HWaddr 00:50:8D:95:C4:19
          inet addr:72.134.40.135  Bcast:255.255.255.255  Mask:255.255.240.0
          inet6 addr: fe80::250:8dff:fe95:c419/64 Scope:Link
          UP BROADCAST NOTRAILERS RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:8738 errors:0 dropped:0 overruns:0 frame:0
          TX packets:127 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:546009 (533.2 Kb)  TX bytes:12113 (11.8 Kb)
          Interrupt:16 Base address:0x8000

eth2      Link encap:Ethernet  HWaddr 00:50:8D:95:C4:1A
          inet addr:192.168.2.1  Bcast:192.168.2.255  Mask:255.255.255.0
          inet6 addr: fe80::250:8dff:fe95:c41a/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:195 errors:0 dropped:0 overruns:0 frame:0
          TX packets:97 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:19274 (18.8 Kb)  TX bytes:13161 (12.8 Kb)
          Interrupt:17 Base address:0x8000

- --

Sean O'Donnell
South Pasadena, CA

sean at seanodonnell.com
http://seanodonnell.com

PGP Public Key ID: 0xF57FB9E5
PGP Public Key Server: http://pgp.mit.edu

*The important thing is not to stop questioning. Curiosity has its own
reason for existing.*

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