Databases, Systems & Networks

Source: nixCraft

MAC is acronym for for Media Access Control address. It is a unique identifier attached to almost most all networking equipment such as Routers, Ethernet cards and other devices.

If you do not have access to router admin interface (via telnet or webbased), use following method to find out router MAC address.

You need to use arp command (available on both Windows, Linux/Unixish systems).

arp manipulates the kernel’s ARP cache in various ways. The primary options are clearing an address mapping entry and manually setting up one. For debugging purposes, the arp program also allows a complete dump of the ARP cache.

arp shows the entries of the specified hosts. If the hostname parameter is not used, all entries will be displayed.

Task: Find out router Mac Address

To find out your router MAC address, use arp command as follows:

$ /usr/sbin/arp -a
OR
$ arp -a
Output:

router (192.168.1.254) at 00:08:5C:00:00:01 [ether] on eth0
fbsd6 (192.168.1.16) at 00:0F:EA:91:04:07 [ether] on eth0

In above example 00:08:5C:00:00:01 is MAC address of my router. If you cannot find MAC address then just ping to your router once (my router had 192.168.1.254 IP)
$ ping 192.168.1.254
And then run (type arp -a) above arp command again. If you have telnet access to router then you can just telnet into router and find out MAC address:
$ telnet 192.168.1.254

Output:

Welcome to nixCraft Router!
Login: admin
Password:

Once logged in type ifconfig command:

$ ifconfig br0

Output:

br0             Link encap:Ethernet  HWaddr 00:08:5C:00:00:01
        inet addr:192.168.1.254  Bcast:192.168.1.255  Mask:255.255.255.0
        UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
        RX packets:48574 errors:0 dropped:0 overruns:0 frame:0
        TX packets:61329 errors:0 dropped:0 overruns:0 carrier:0
        collisions:0 txqueuelen:0
        RX bytes:9146189 (8.7 MiB)  TX bytes:74456679 (71.0 MiB)

Please note that your interface name (br0) could be different. You can also use ifconfig -a command.

Windows XP/NT/2003 find out Router Mac address

If you are using Microsoft Windows XP then you need to open MS-DOS shell prompt first. Click on Start > Run > Type cmd command followed by ENTER key. Then at C:\> prompt, type arp command as follows:

C:\> arp -a