I can't find eth0 (or don't know how to look)

Here's the deal: I've got RH 7.3 running just fine until an hour ago.
I crashed a Matlab session and decided it was a good time to reboot
my machine. The shutdown process hung at some point leaving the
note "No more processes at this level", and after about 5 minutes
I hit the reset button.

When the machine came back up, it complained about the ethernet
interface, saying this:

"Bringing up interface eth0: Error, some other host already uses address
[my IP address]"

Plus, I get a big fat red "FAILED" on the screen, just to make me
feel better.

How do I get my box to behave again?

I'm pretty much out of clues, so any you folks have would be
a pure treat.

Thanks,

Dale.

hey dale,

could you give some details : are you in a LAN ?

vivekian

W. Dale Hall wrote:
> Here's the deal: I've got RH 7.3 running just fine until an hour ago.
> I crashed a Matlab session and decided it was a good time to reboot
> my machine. The shutdown process hung at some point leaving the
> note "No more processes at this level", and after about 5 minutes
> I hit the reset button.
>
> When the machine came back up, it complained about the ethernet
> interface, saying this:
>
> "Bringing up interface eth0: Error, some other host already uses address
> [my IP address]"
>
> Plus, I get a big fat red "FAILED" on the screen, just to make me
> feel better.
>
> How do I get my box to behave again?
>
> I'm pretty much out of clues, so any you folks have would be
> a pure treat.
>
> Thanks,
>
> Dale.
>
What does "ifconfig -a" report?

I'm going to make a guess and assume two things: the system is on a
network with a dhcp server (possibly a router), and the machine has a
script with a hardcoded IP address that it tries to use at boot. Now
that the machine is up, I suggest trying to assign a different IP for
eth0 on the same subnet.

eg., if the machine expects eth0 to have the IP 10.1.190.10, I suggest
pinging 10.1.190.11 (to check if a second machine is using it), and if
it's free, run "ipconfig eth0 inet 10.1.190.11". Now on the machine,
try and ping other machines on the network and see if your issue is
resolved.

vivekian wrote:
> hey dale,
>
> could you give some details : are you in a LAN ?
>
> vivekian
>
Yes. I have a fixed IP address (unlike all but one other
machine on this LAN), due to my Matlab license server
needing to see a specific IP address.

Dale (posting from home rather than work)

On Sat, 19 Nov 2005 04:56:45 +0000, Nicholas Andrade wrote:

>> "Bringing up interface eth0: Error, some other host already uses address
>> [my IP address]"

well. that's the problem.

"W. Dale Hall" <wd-(E-Mail Removed)> writes:

>vivekian wrote:
>> hey dale,
>>
>> could you give some details : are you in a LAN ?
>>
>> vivekian
>>
>Yes. I have a fixed IP address (unlike all but one other
>machine on this LAN), due to my Matlab license server
>needing to see a specific IP address.

ifconfig -a
will show if you have eth0, and tell you what IP address it thinks it has.
modprobe eth0
will probably install the ethernet card driver, assuming it is entered into
/etc/modprobe.conf

W. Dale Hall wrote:

> Here's the deal: I've got RH 7.3 running just fine until an hour ago.
> I crashed a Matlab session and decided it was a good time to reboot
> my machine. The shutdown process hung at some point leaving the
> note "No more processes at this level", and after about 5 minutes
> I hit the reset button.
>
> When the machine came back up, it complained about the ethernet
> interface, saying this:
>
> "Bringing up interface eth0: Error, some other host already uses address
> [my IP address]"
>
> Plus, I get a big fat red "FAILED" on the screen, just to make me
> feel better.
>
> How do I get my box to behave again?
>
> I'm pretty much out of clues, so any you folks have would be
> a pure treat.
>
> Thanks,
>
> Dale.

I had a few crashes with my Fedora PC where even rebooting would not
get the ethernet port back. The /etc/init.d/network script
would fail when it tried to find the eth0 hardware
(oddly, running dmesg showed that the kernel saw the eth0 port)

I think the problem is that on ATX boards, the motherboard has components
that are still powered. For example if your board has wake on LAN, then
the ethernet circuitry has power on it even if you power off the PC
(obviously it has to, how could it detect network activity to wake up the
PC). I had to power down the box and then toggle the hardware
power switch on the back of the power supply. After that it could see the
port again. I've had similar problems with some Scsi cards where a warm
boot cycle would not clear a problem on the scsi card and I had to do
a cold reboot (ie complete cycle the power).

so keeping it simple, I'd suggest you try a full power down, then reboot
as see if it finds the port.

mark

W. Dale Hall wrote:

.... a buncha stuff, culminating in:

> How do I get my box to behave again?
>
> I'm pretty much out of clues, so any you folks have would be a pure
> treat.
>
> Thanks,
>
> Dale.
>

Thanks to all for the hints; the clues regarding use of
ifconfig (coupled with downloading an ip scanner to see
what was what) turned out to do the trick.

One thing that left me puzzled was that (1) there was
apparently a new device at the IP address I wanted
(confirmed by a ping response even when my linux box
was physically disconnected from the LAN), (2) when I
assigned my linux box to that IP address (via ifconfig),
the thing worked (except for connection to the internet;
I got LAN access only), despite the presence of this
device up to the point of my reassigning the IP address,
and when I rebooted, the other device was gone and my
machine assumed the correct address as though nothing
had happened.

I'm not complaining, but I'm surely confused enough.

Thanks to all, again,

Dale.

W. Dale Hall wrote:
> Thanks to all for the hints; the clues regarding use of
> ifconfig (coupled with downloading an ip scanner to see
> what was what) turned out to do the trick.
>
> One thing that left me puzzled was that (1) there was
> apparently a new device at the IP address I wanted
> (confirmed by a ping response even when my linux box
> was physically disconnected from the LAN), (2) when I
> assigned my linux box to that IP address (via ifconfig),
> the thing worked (except for connection to the internet;
> I got LAN access only), despite the presence of this
> device up to the point of my reassigning the IP address,
> and when I rebooted, the other device was gone and my
> machine assumed the correct address as though nothing
> had happened.
>
> I'm not complaining, but I'm surely confused enough.
>
> Thanks to all, again,
>
> Dale.
>

Glad to hear it worked out. It's my guess that the reason you couldn't
connect outward was because of the way you assigned your IP (I imagine
you simply used ifconfig eth0 inet XXX.XXX.XXX.XXX). You just set an
address -- rather than used dhcp to grab an IP -- so your resolv.conf
probably wasn't configured. Resolv.conf points to you DNS server, I'd
be willing to bet you actually could connect to the internet via IP
addresses, but not by URL's. When you rebooted, the machine grabbed the
IP via DHCP during the startup.

Nicholas Andrade <(E-Mail Removed)> writes:

>W. Dale Hall wrote:
>> Thanks to all for the hints; the clues regarding use of
>> ifconfig (coupled with downloading an ip scanner to see
>> what was what) turned out to do the trick.
>>
>> One thing that left me puzzled was that (1) there was
>> apparently a new device at the IP address I wanted
>> (confirmed by a ping response even when my linux box
>> was physically disconnected from the LAN), (2) when I

Linux is intelligent to know that if you are refering to y ourself you do
not need to go onto the net. Yourself is already present where yourself is
located.


>> assigned my linux box to that IP address (via ifconfig),
>> the thing worked (except for connection to the internet;
>> I got LAN access only), despite the presence of this
>> device up to the point of my reassigning the IP address,
>> and when I rebooted, the other device was gone and my
>> machine assumed the correct address as though nothing
>> had happened.
>>

No idea what you mean.

>> I'm not complaining, but I'm surely confused enough.
>>
>> Thanks to all, again,
>>
>> Dale.
>>

>Glad to hear it worked out. It's my guess that the reason you couldn't
>connect outward was because of the way you assigned your IP (I imagine
>you simply used ifconfig eth0 inet XXX.XXX.XXX.XXX). You just set an
>address -- rather than used dhcp to grab an IP -- so your resolv.conf
>probably wasn't configured. Resolv.conf points to you DNS server, I'd
>be willing to bet you actually could connect to the internet via IP
>addresses, but not by URL's. When you rebooted, the machine grabbed the
>IP via DHCP during the startup.