Find the network card

Jason.nix · 11-07-2023, 11:46 PM

Hello,
A PC has two network cards, both of which are the same model. How to find out which MAC address belongs to which network card?
It is not possible to open the PC case and there is no active network.

Thank you.

wpeckham · 11-08-2023, 12:07 AM

Why. If there is no network, why would you care about the MAC addresses?

lvm_ · 11-08-2023, 05:35 AM

Connect them to each other.

camorri · 11-08-2023, 08:08 AM

The command ip -d a will tell you mac address.

Configure one port, and you will see with the IP command eth0 or eth1 assigned; ( or what ever name).

michaelk · 11-08-2023, 09:45 AM

I think the OP wants to match the MAC address with the physical port on the computer. Connecting them together would cause both to be active but you would not know which one was which. About the only thing I can think of at the moment would be to build a loopback plug.

lvm_ · 11-08-2023, 12:23 PM

Quote:

Originally Posted by michaelk

Connecting them together would cause both to be active but you would not know which one was which.

You can determine it by PCI slot number which is programmatically available (actually I suspect that MAC address of a card is visible even if it is not connected, but I am too lazy to check :) If they are both built-in, then yes, bummer.

michaelk · 11-08-2023, 01:22 PM

I assume built-in but yes if they are PCI devices it should be fairly easy to tell.

dugan · 11-08-2023, 02:25 PM

Is it your "thing" to just make up random questions?

I'm going to answer this one with a question: what do I hope to do with this information?

wpeckham · 11-08-2023, 02:34 PM

MAC addresses are displayed as ether in the output of

Code:

ip link show

. Figuring out the map from the reported NIC ports to the physical port connections might be interesting, but the easy way is to connect one and detect the link state.

Jason.nix · 11-15-2023, 12:23 AM

Quote:

Originally Posted by lvm_

Connect them to each other.

Hello,
Thank you so much for your reply.
Connecting them to each other causes both network cards to be in up mode, not one of them. If only one of them was in up mode, then it would be a good idea. What does this help?

Jason.nix · 11-15-2023, 12:49 AM

Quote:

Originally Posted by camorri

The command ip -d a will tell you mac address.

Configure one port, and you will see with the IP command eth0 or eth1 assigned; ( or what ever name).

Hello,
Thank you so much for your reply.
Then eth0 or eth1 is related to which physical card?

chrism01 · 11-15-2023, 05:22 PM

See post #9; just connect one and check it.
Then disconnect that one and connect the other & check ....

Jason.nix · 11-21-2023, 11:24 PM

Quote:

Originally Posted by chrism01

See post #9; just connect one and check it.
Then disconnect that one and connect the other & check ....

Hello,
Thank you so much for your reply.
Do you mean I remove one of the network cards? If yes, then I must say that it is not possible to open the case door.

michaelk · 11-22-2023, 05:06 AM

No. Connect one to your other computer or switch and test each port for an active link using ethtool.

LordSweeper · 11-22-2023, 07:32 AM

Hello, I am new here.