Finding your MAC address

Your machine's MAC address is a network identifier for your computer, which uniquely identifies your computer on the network, and which is often used (1) when creating a licence for a specific computer, or (2) when registering a laptop on the network (one of these is probably why you're reading this page). It's the ‘ethernet address’ of your wired or wireless interface (though this is a bit of a misnomer). It's not in any way specific to Apple Macs (though Macs have MACs, too, and this is entertainingly distinct from MAC, for those of you keeping up at the back).

A MAC address consists of 12 characters from 0–9 and a–f, in pairs separated by colons or dashes. For example 12:34:56:78:9a:bc or 12-34-56-78-9A-BC.

If you need to quote your MAC address, there are various ways you can do so, depending on your platform.

Notes:

In each of the cases below, you should generally ensure that you are quoting a MAC address of an ethernet interface, and not a WiFi MAC address. If you're only quoting a MAC address for licensing purposes, it doesn't matter which one it is.
If you connect to ethernet via a dongle of some type – for example a USB-to-ethernet adapter – then the dongle will have the MAC address (and it's technically the dongle that is given access to the network, not your computer). Bear that in mind when looking through the list of available interfaces on your computer. If it's not obvious which one this is, just cut-and-paste the entire ifconfig output into an email and let IT staff do the detective-work.

Linux §

At a shell prompt, type ifconfig. This lists the network interfaces which are available. There will typically be one called eth0 or enp2s0f0, or something similar, depending on the distribution. In this stanza, search for HWaddr or ether.

For example:

    % ifconfig
    eth0      Link encap:Ethernet  HWaddr 00:25:90:59:9e:60
              inet addr:130.209.45.115  Bcast:130.209.45.255  Mask:255.255.255.0
              inet6 addr: fe80::225:90ff:fe59:9e60/64 Scope:Link
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:152522807 errors:0 dropped:8050 overruns:2 frame:0
              TX packets:167691945 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000
              RX bytes:50057940479 (50.0 GB)  TX bytes:21142845126 (21.1 GB)
              Memory:dff60000-dff80000

    eth1      Link encap:Ethernet  HWaddr 00:25:90:59:9e:61
              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)
              Memory:dffe0000-e0000000

    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:1804940 errors:0 dropped:0 overruns:0 frame:0
              TX packets:1804940 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:0
              RX bytes:347380165 (347.3 MB)  TX bytes:347380165 (347.3 MB)

Here, you can see that the eth0 interface has both a HWaddr and an inet addr (IP address), marked in red. This machine happens to have two interfaces – the other is called eth1. In this case, it appears to be the eth0 interface that the user connects to the network, and which is therefore the one to be quoted.

OS X/macOS §

You can use ifconfig at a shell prompt, as above (the ethernet and wireless interfaces look like en0 and en1 on OS X).

Alternatively, you can go to the ‘Network’ preference pane, in System Preferences, then click on ‘Advanced...’, and find the ‘Hardware’ tab within that, to see your MAC address quoted as below:

OS X hardware preferences

Windows §

First, start a ‘command prompt’ (opening a command prompt is done in different ways on different versions of Windows, but should be something like: click Start, click Run, type cmd, and then click ‘OK’; Google is your friend).

Then type ipconfig /all and search through the output for ‘physical address’. It might look something like this.

Connection-specific DNS Suffix  . :
Description . . . . . . . . . . . : Qualcomm Atheros XXX Gigabit Ethernet Controller
Physical Address. . . . . . . . . : 12-34-56-78-9A-BC
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::1234:5678:9abc:12f%14(Preferred)
IPv4 Address. . . . . . . . . . . : 130.209.99.99(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 130.209.99.1
DHCPv6 IAID . . . . . . . . . . . : 12345678
DHCPv6 Client DUID. . . . . . . . : 00-01-02-00-12-34-56-78-9A-BC-11-11-11-11
DNS Servers . . . . . . . . . . . : 130.209.4.16
                                    130.209.4.18
NetBIOS over Tcpip. . . . . . . . : Enabled

There may be quite a lot of output here, especially if your machine has multiple network ports. Try to quote an address which has an IPv4 Address associated with it, as here. If you are trying to register a laptop, you will need to find the entry associated with the ‘ethernet’ port. If in doubt, just cut-and-paste the entire ipconfig output into an email and let IT staff do the detective-work.

There are various ways of finding this ‘physical address’ through the windows GUI interface, but the above method is the most nearly cross-version.