[ShadowAce]

ifconfig is being deprecated.

Use the command ip a as the replacement, if your distro provides it.

[asinclair]

ip link show This will show you the information for EVERY interface in your computer. So you need to look at the line set for the link/ether [eg MAC address] of the interface you need to report. Example:

3: enp0s25.2@enp0s25: mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
link/ether 18:03:73:b0:ea:10 brd ff:ff:ff:ff:ff:ff

Here is what you need to provide: 18:03:73:b0:ea:10

Some system administrators will require you to reformat this address to match what the router they are using expects. For example, for some Cisco equipment they will want 1803.73b0.ea10 -- if said sysadmin is a real tool.