MAC Addressing

Find a MAC Address

The method used to find a MAC address depends on the type of network device involved. All popular network operating systems contain utility programs that allow you to find (and sometimes change) MAC address settings.

Find a MAC Address in Windows

In Windows 95, Windows 98 and Windows ME, the winipcfg utility displays the computer's MAC address. Use the ipconfig utility (with the /all option) in Windows NT and any newer versions of Windows.

Both 'winipcfg' and 'ipconfig' may display multiple MAC addresses for one computer. One MAC address exists for each installed network card. Additionally, Windows maintains one or more MAC addresses that are not associated with hardware cards.

For example, Windows dial-up networking uses virtual MAC addresses to manage the phone connection as if it were a network card. Some Windows VPN clients likewise have their own MAC address. The MAC addresses of these "virtual" network adapters are the same length and format as true hardware addresses.

 

Find a MAC Address in Unix or Linux

The specific command used in Unix to find a MAC address varies depending on the version of the operating system. In Linux and in some forms of Unix, the command "ifconfig -a" returns MAC addresses.

You can also find MAC addresses in Unix and Linux in the boot message sequence. These operating systems display the computer's MAC address on-screen as the system reboots. Additionally, boot-up messages are retained in a log file (usually "/var/log/messages" or "/var/adm/messages").

Find a MAC Address on the Macintosh

You can find MAC addresses on the Macintosh in the TCP/IP Control Panel. If the system is running Open Transport, the MAC address appears under the "Info" or "User Mode/Advanced" screens. If the system is running MacTCP, the MAC address appears under the "Ethernet" icon.

Summary - How to Find a MAC Address

The list below summarizes options to find a computer's MAC address:

• Windows 95 and newer: winipcfg
• Windows NT and newer: ipconfig /all
• Linux and some Unix: ifconfig -a
• Macintosh with Open Transport: TCP/IP Control Panel - Info or User Mode/Advanced
• Macintosh with MacTCP: TCP/IP Control Panel - Ethernet icon