How do I find out the MAC address of my Linux or FreeBSD system?

Q. Can you tell me how can I find out MAC address under Linux or FreeBSD server?

A. A mac address is acronym for media access control address, is a unique address assigned to almost all-networking hardware such as Ethernet cards, router etc. Most layer 2 network protocols use one of three numbering spaces managed by the IEEE: MAC-48, EUI-48, and EUI-64, which are designed to be globally unique. (see mac address at wikipedia for more information).

Following command work with Linux and other UNIX oses:

ifconfig command

Ifconfig is used to configure the kernel-resident network interfaces.

In order to find out MAC address of system you can use ifconfig command as follows:
$ /sbin/ifconfig | grep HWaddr
Output:

eth0      Link encap:Ethernet  HWaddr 00:0F:EA:91:04:07

$ /sbin/ifconfig

eth0      Link encap:Ethernet  HWaddr 00:0F:EA:91:04:07
        inet addr:192.168.1.2  Bcast:192.168.1.255  Mask:255.255.255.0
        inet6 addr: fe80::20f:eaff:fe91:407/64 Scope:Link
        UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
        RX packets:60400 errors:0 dropped:0 overruns:0 frame:0
        TX packets:109216 errors:0 dropped:0 overruns:0 carrier:0
        collisions:0 txqueuelen:1000
        RX bytes:69273219 (66.0 MiB)  TX bytes:14285799 (13.6 MiB)
        Interrupt:18 Base address:0xc000

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:3869 errors:0 dropped:0 overruns:0 frame:0
        TX packets:3869 errors:0 dropped:0 overruns:0 carrier:0
        collisions:0 txqueuelen:0
        RX bytes:396498 (387.2 KiB)  TX bytes:396498 (387.2 KiB)

OR as a root user type following command:

# grep eth0 /var/log/dmesg

eth0: RealTek RTL8139 at 0xc000, 00:0f:ea:91:04:07, IRQ 18
eth0:  Identified 8139 chip type 'RTL-8100B/8139D'
eth0: link up, 100Mbps, full-duplex, lpa 0x45E1

FreeBSD example

# ifconfig
Output:

lnc0: flags=108843 mtu 1500
        inet 74.xx.yy.zzz netmask 0xfffffff0 broadcast 74.xx.yyy.zzz
        ether 00:0c:29:b8:92:8b
plip0: flags=108810 mtu 1500
lo0: flags=8049 mtu 16384
        inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3 
        inet6 ::1 prefixlen 128 
        inet 127.0.0.1 netmask 0xff000000

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.

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6 comment

If your FreeBSD machine is up too long, the dmesg might have cycled and is not visible. The ifconfig command does not display the HW address in FreeBSD. The sysctl command does not hold the value, so, I am basically lost. :(

thank you

Use

ifconfig -a

because that will show you the MAC address even if you’re not connected.

Thanks for the help.

Just want to know how would I find out the MAC address of a linux machine on my network(remotely)?

Thanks in advance.

Now,
ifconfig | grep ether

OutPut:
ether 00:90:7c:5d:0b:24
ether 00:c9:c2:87:94:83
ether 00:05:58:57:e5:74

how to get same thing(00:90:7c:5d:0b:24) in windows operating system
using PHP

Roel says:
January 18, 2008 at 9:01 am
If your FreeBSD machine is up too long, the dmesg might have cycled and is not visible. The ifconfig command does not display the HW address in FreeBSD. The sysctl command does not hold the value, so, I am basically lost. :(
thanker says:
November 20, 2008 at 6:23 pm
thank you
Ricardo Fabbri says:
July 25, 2009 at 12:39 am
Use
ifconfig -a
because that will show you the MAC address even if you’re not connected.
Jeremy says:
August 4, 2009 at 1:53 pm
Thanks for the help.
Just want to know how would I find out the MAC address of a linux machine on my network(remotely)?
Thanks in advance.
Techie Talks says:
July 2, 2012 at 1:20 am
Now,
ifconfig | grep ether
OutPut:
ether 00:90:7c:5d:0b:24
ether 00:c9:c2:87:94:83
ether 00:05:58:57:e5:74
Ravi says:
September 5, 2014 at 6:37 am
how to get same thing(00:90:7c:5d:0b:24) in windows operating system
using PHP

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