How can I find a MAC of hardware attached via ethernet cable?

[BazookaJo]

Hi guys

I have been working nicely with an industrial scanner that is controlled by a Linux PC via an ethernet cable, but the hard drive has died I need to get it working again.

The problem is that the main PCB has a Realtek RTL8019AS ethernet controller chip, which I believe is used in the most basic way possible, applied straight off-the-shelf and unconfigured.

To utilise the chip ARP commands are used to assign an IP address to the chips MAC address e.g. something like:
arp -s 192.168.2.5 00-05-a4-00-a8-f8

Unfortunately the actual MAC address was lost along with the HD

Any ideas how do I find the MAC address again?

Th only thing I could have a reasonable guess at is that the chip will have a default subnet of 255.255.0.0 or 255.255.255.0

Fingers crossed and many thanks in advance.

Tony

[jayd512]

So it's the MAC of an integrated chip that you're looking for, right?
I would think you have two fairly simple options.

First, provided you have an optical drive on the computer, boot up to a LiveCD and do

ifconfig -a

Second, depending on your previous setup, would you have a router that may have had a MAC filter enabled?

[BazookaJo]

So it's the MAC of an integrated chip that you're looking for, right?
I would think you have two fairly simple options.

First, provided you have an optical drive on the computer, boot up to a LiveCD and do

ifconfig -a

Second, depending on your previous setup, would you have a router that may have had a MAC filter enabled?

Tried the ifconfig -a route but it never did show up even when it worked.....strange

I even tried Wireshark from a PC, there was a lot of traffic when you turned on the scanner but it all seemed to be one-way.

Perhaps the router could be the way to go.....

Many thanks

Tony

[jayd512]

Tried the ifconfig -a route but it never did show up even when it worked.....strange

What do you mean?
Did you get any output at all?
You should have had something like this:

eth0      Link encap:Ethernet  HWaddr 00:1e:ec:e1:01:c5  
          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:28 Base address:0x2000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:12 errors:0 dropped:0 overruns:0 frame:0
          TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:720 (720.0 B)  TX bytes:720 (720.0 B)

[BazookaJo]

Hi Flintlock

Yes it did show the IP details for the network card and local loopback, but sadly nothing else.

Going to stick it into a DHCP router tonight and see if I get any life.

Failing that I have an old crossover cable for what it's worth - desperate time and all that.....


Thanks again

[BazookaJo]

Minor update

Plugged the proprietry PCB into a DHCP router, but again, no sign of it.

I get the feeling that the 'ethernet' enabled PCB was setup without attention to any TCP/IP protocols - hence the need to use ARP the MAC address to give it any kind of IP presence.

Also tried WireShark when connected with a crossover cable, but again - knack all.

The fun continues.

[jayd512]

Hi Bazooka.

Just to clarify... the MAC address in question wasn't shown in ifconfig -a?

Like this:

 HWaddr 00:1e:ec:e1:01:c5

We are both looking for the MAC... right?

[BazookaJo]

Hi Bazooka.

Just to clarify... the MAC address in question wasn't shown in ifconfig -a?

Like this:

 HWaddr 00:1e:ec:e1:01:c5

We are both looking for the MAC right?

Hi Flintlock

Yes - it is the MAC I am after, and yes no sign of the MAC in ifconfig -a

As I say, the only way it became usable was via by manually giving the MAC an IP address via ARP e.g.
arp -s 192.168.2.5 00-05-a4-00-a8-f8


Best regards

Tony