How to Find MAC addr

  • Thread starter Thread starter Dan
  • Start date Start date
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Dan

This may be a stupid question but I have a unix/linux computer on my network
and don't know how to get its MAC address. Is there a unix command that I
can do on the computer or a way to use a command on my PC to extract it.
Like PING or NSLOOKUP etc.

dan
 
3c273 said:
Ping the machine and then type "arp -a".
Click to expand...


That will work.

Go to the Unix box and type "ifconfig -a " ON THE Linux
box should do it. (Some forms of Unix may require adjusting
the swich -a)
 
I tried that but was not confident of the results. Heres why:

The unix computer that I am talking about is actually an IBM x365 server
running VMWare. Under VMware I created 5 "virtual" servers running W2K3.

Here's the strange part. To test arp, I ran it against one of my servers
and got the Physical address then logged into the server and clicked the
network icon and checked the details and got a different MAC.

Interesting hey.....
 
Dan said:
I tried that but was not confident of the results. Heres why:

The unix computer that I am talking about is actually an IBM x365 server
running VMWare. Under VMware I created 5 "virtual" servers running W2K3.
Click to expand...

Well, if you run arp on a machine it will SHOW YOU
the MAC address it will use to send the info over the
net (all directed traffic really travels by MAC address).
Here's the strange part. To test arp, I ran it against one of my servers
and got the Physical address then logged into the server and clicked the
network icon and checked the details and got a different MAC.
Click to expand...

Not strange at all. How do the machines within a virtual network
uniquely identify themselves on THAT network?

I didn't know it, but it makes perfect sense that on the virtual NICs
they make up a MAC address to differentiate each other.

Of course, from the "real" network, the other machines will know
them as the PHYSICAL NIC on the host operating system.
Interesting hey.....
Click to expand...

And predictable.
 
Virtual Machine / Virtual Server permits either Dynamic or Static MACs.
Unless you have a specific reason to set the MAC address for a virtual
machine, Microsoft recommends you use Dynamic. If you select Static, then
you should type a static MAC address in the space provided. Virtual Server
allocates a new dynamic MAC address to the virtual machine from the pool of
available addresses.

You must either change the static MAC address of the virtual machines or run
any virtual machines with identical static MAC addresses at different times.
If virtual machines with identical static MAC addresses are run at the same
time, virtual machine networking may not work properly. To avoid this
problem, Microsoft recommends that you use dynamic MAC addresses.

Neither MAC address can be physical MAC one (or it's improbable) unless you
intentionally type it in.
 
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