Geting MAC address from a network connection

Hi,
i have some computers that are in the same network.
Every computer has it's bios password protected, so i cann't boot with
floppy or cdrom.
What i thoght to do is: connect my laptop to this network with regular
network cable, or connect my laptop with twisted network cable to one
of the computers.
Now, is it possible to obtain the MAC address of the computer, with my
laptop running linux.
My question has 2 steps:
1. the computer is on the boot faze and don't run any OS. (Its like
using just the data link layer, with no layers above).
2. the computer loads Redhat from network, and obtain ip with dhcp,
but stuck in gdm to get password that i don't have.

(I can change my laptop's MAC with ifconfig)

tnx
tech

tech wrote:

> Hi,
> i have some computers that are in the same network.
> Every computer has it's bios password protected, so i cann't boot with
> floppy or cdrom.
> What i thoght to do is: connect my laptop to this network with regular
> network cable, or connect my laptop with twisted network cable to one
> of the computers.
> Now, is it possible to obtain the MAC address of the computer, with my
> laptop running linux.
> My question has 2 steps:
> 1. the computer is on the boot faze and don't run any OS. (Its like
> using just the data link layer, with no layers above).
> 2. the computer loads Redhat from network, and obtain ip with dhcp,
> but stuck in gdm to get password that i don't have.
>
> (I can change my laptop's MAC with ifconfig)
>
> tnx
> tech


You can see the MAC address by running ifconfig without arguments
It is shown on the second line in the eth0 section as HWaddr.

Why do you want to change the MAC address?

Clive Dove <(E-Mail Removed)> thus wrote:
> > laptop running linux.
> > My question has 2 steps:
> > 1. the computer is on the boot faze and don't run any OS. (Its like
> > using just the data link layer, with no layers above).
>
> You can see the MAC address by running ifconfig without arguments
> It is shown on the second line in the eth0 section as HWaddr.
>
> Why do you want to change the MAC address?
>
>

I think what the OP wants is to get the MAC address
of the other m/c while they are still in BIOS, as
he has mentioned.

Interesting question...

--
arc_of_descent

In article <(E-Mail Removed)>, tech wrote:
> Every computer has it's bios password protected, so i cann't boot with
> floppy or cdrom.

Do you have permission to do this? Ask the sysadmin to enable CD-ROM
booting. Or if you're the new admin without this information, use the
motherboard jumper to clear the CMOS password.

BTW if the system is using a DOS-based OS (Win9x) you can get it into
Linux using loadlin. It is not possible to secure DOS against such
attacks, the many so-called security tools notwithstanding.

> What i thoght to do is: connect my laptop to this network with regular
> network cable, or connect my laptop with twisted network cable to one
> of the computers.

To what end? Simply to get your laptop on the network? Sounds to me like
this may be a prohibited activity. Talk to the netadmin!

> Now, is it possible to obtain the MAC address of the computer, with my

The MAC address is not a feature of the "computer" unless it's a
motherboard with onboard Ethernet. Most NIC's have the MAC available,
either on a sticker or silk-screened on. (This is likely the case even
for an onboard Ethernet controller.) When you open it to reset the CMOS,
look for the MAC.

> My question has 2 steps:
> 1. the computer is on the boot faze and don't run any OS. (Its like
> using just the data link layer, with no layers above).

I don't understand. I'm not aware of BIOS-level use of the NIC, except
for BOOTP of course.

> 2. the computer loads Redhat from network, and obtain ip with dhcp,
> but stuck in gdm to get password that i don't have.

Aha! Bootp! Why don't you just boot from the laptop's hard drive? I
don't think PCMCIA NIC's are bootable.

> (I can change my laptop's MAC with ifconfig)

Yes, when it is running Linux and you have root.
--
/dev/rob0 - preferred_email=i$((28*28+28))@softhome.net
or put "not-spam" or "/dev/rob0" in Subject header to reply

Tnx for your answers, but i didn't got what i need.
I will ask it another way:
1. Can i get MAC address of a nic from a remote computer?
2. Can a network card send its MAC, even there is no os running?
tnx

In article <(E-Mail Removed)>, tech wrote:
> 1. Can i get MAC address of a nic from a remote computer?

Use ping or any kind of network connection thereto, and it will be in
your arp(8) table: /sbin/arp or "cat /proc/net/arp".

> 2. Can a network card send its MAC, even there is no os running?

If it has a bootable ROM chip, and if the BIOS is configured to boot
from it, it will send a bootp request. Run a bootp server, and I'm sure
it will log the MAC. I don't know of any other way.

Sounds like your opponent may have done a good job in securing this
network. There could also be intrusion detection and log monitor systems
at work. If not there should be.
--
/dev/rob0 - preferred_email=i$((28*28+28))@softhome.net
or put "not-spam" or "/dev/rob0" in Subject header to reply

/dev/rob0 <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>. ..
> In article <(E-Mail Removed)>, tech wrote:
> > 1. Can i get MAC address of a nic from a remote computer?
>
> Use ping or any kind of network connection thereto, and it will be in
> your arp(8) table: /sbin/arp or "cat /proc/net/arp".
>
> > 2. Can a network card send its MAC, even there is no os running?
>
> If it has a bootable ROM chip, and if the BIOS is configured to boot
> from it, it will send a bootp request. Run a bootp server, and I'm sure
> it will log the MAC. I don't know of any other way.
>
> Sounds like your opponent may have done a good job in securing this
> network. There could also be intrusion detection and log monitor systems
> at work. If not there should be.

tnx,
i will try your sugesstions.
The computer is booting from the network, so i guess it will send a bootp request.
When i'll have my conclusion i will post it to this thred.