[vox-tech] different MAC address when using "ifconfig" and "arp"

[Jeffrey J. Nonken]

The router is going to have more than one MAC. The published one is probably for the WAN interface, which is useful to know if your provider is doing MAC locking.

That's my WAG.

On Sun, 13 Apr 2008 16:36:37 -0400, Hai Yi wrote:
> Thank you, Bryan:
> 
> I think you are pretty much correct: it looks like this "arp"
> command is equivalent to another command "ip neighbor", which
> pretty much speaks for itself. However, I checked the MAC on my
> router, it appears to be   00:14:BF:D3:AE:2A, which is one digit
> greater in the last section than the one from arp command.
> (00:14:BF:D3:AE:29 ) Why is that?
> 
> Thanks,
> Hai
> 
> On Sun, Apr 13, 2008 at 2:15 PM, Bryan Richter
> <bryan.richter at gmail.com> wrote:
> 
>> 2008/4/13, Hai Yi <yihai2004 at gmail.com>:
>> 
>> 
>>> Hello,
>>> 
>>> I thought I can get my ether card's MAC address by using either
>>> "ifconfig eth0" command or "arp -v" command, but these commands
>>> returned different MAC address(00:16:E6:5C:DA:B8 vs
>>> 00:14:BF:D3:AE:29). Did I miss something here?
>>> 
>>> I am using Ubuntu and the following are the results:
>>> 
>>> 
>>> hai at zodiac:~$ ifconfig eth0
>>> eth0      Link encap:Ethernet  HWaddr 00:16:E6:5C:DA:B8 inet
>>> addr:192.168.1.103  Bcast:192.168.1.255  Mask:255.255.255.0
>>> inet6 addr: fe80::216:e6ff:fe5c:dab8/64 Scope:Link UP BROADCAST
>>> RUNNING MULTICAST  MTU:1500  Metric:1 RX packets:27120 errors:0
>>> dropped:0 overruns:0 frame:0 TX packets:26884 errors:0
>>> dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000
>>> RX bytes:6831509 (6.5 MiB)  TX bytes:3820509 (3.6 MiB)
>>> Interrupt:16
>>> 
>>> hai at zodiac:~$ arp -v
>>> Address                  HWtype  HWaddress           Flags Mask
>>> 
>> Iface
>>> .                        ether   00:14:BF:D3:AE:29   C
>> eth0
>>> Entries: 1      Skipped: 0      Found: 1
>>> 
>>> 
>>> Thanks a lot!
>>> Hai
>>> 
>> 
>> I think arp shows your adapter's neighbors, not the adapter
>> itself. I only just read the man page for the first time,
>> however, its results when I run it seem to confirm that:
>> 
>> 192.168.1.1              ether   00:18:4D:25:82:0D   C
>> ath0
>> 
>> My adapter's neighbor is, indeed, 192.168.1.1 (my router).
>> 
>> ifconfig, on the other hand, seems like a much better place to
>> find info about the device, itself. Also, the address it gives
>> for my device matches the sticker that the manufacturer put on my
>> laptop. :)
>> 
>> -Bryan
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>> vox-tech at lists.lugod.org
>> http://lists.lugod.org/mailman/listinfo/vox-tech
>> 
>> 
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