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tmr250z
join:2009-02-25
Southeast MI

tmr250z

Member

[Tomato] FInd WAN port & Wireless Interface original MAC address

A couple of months ago, I changed my WAN port & Wireless Interface MAC addresses in order to get a new IP address. I wrote down the original addresses, but somehow I lost the paper where I wrote them down on. Everything works just fine now as is, but I'm just curious if there's a way to find out what the original MAC addresses were?

Bill_MI
Bill In Michigan
MVM
join:2001-01-03
Royal Oak, MI
TP-Link Archer C7
Linksys WRT54GS
Linksys WRT54G v4

4 edits

Bill_MI

MVM

Re: [Tomato] FInd WAN port & Wireless Interface original MAC add

Wireless MAC at telnet or ssh:
nvram get il0macaddr

LAN MAC:
nvram get et0macaddr

WAN MAC is not stored in these base variables and usually is simply the value between LAN and Wireless. Wireless should be exactly 2 above LAN.

I believe Tomato, like OpenWrt I run, doesn't change these variables but only working varables like lan_hwaddr, wan_hwaddr and wl0_hwaddr. But I could be wrong.

Get a bunch of what you have configured with:

nvram show | grep addr

Otherwise, there is a way to extract the semi-permanent CFE area of flash to get it. Or... reset to defaults will get you back, too.

HTH
tmr250z
join:2009-02-25
Southeast MI

1 edit

tmr250z

Member

said by Bill_MI:

Or... reset to defaults will get you back, too.
I cleared the NVRAM and rest it back to defaults. It didn't work, they're still the same.
said by Bill_MI:

Otherwise, there is a way to extract the semi-permanent CFE area of flash to get it.
Could you elaborate on this please?

Bill_MI
Bill In Michigan
MVM
join:2001-01-03
Royal Oak, MI
TP-Link Archer C7
Linksys WRT54GS
Linksys WRT54G v4

3 edits

Bill_MI

MVM

I made some notes when playing with Tomato 1.16 last March and find the CFE area is /dev/mtdblock/0, same as OpenWrt mapping. Now to put my hardware hat on and get out 0x1E00 offset the easiest way I can think of...

dd if=/dev/mtdblock/0 bs=1 skip=7680 count=17

This will output 17 bytes starting at 0x1E00 which should be the ASCII of the unique base MAC (used for LAN) followed by "17+0 records in" that can be ignored.

This is the only value permanently stored. When you cleared NVRAM, the CFE boot code *should* have initialized this value in the et0macaddr variable then add 2 to the value and put it in il0macaddr (ultimately used as wireless MAC).

BTW, this is for WRT54GSv3, WRT54Gv4 and should work on the WRT54GL and others. Hope you have compatible.

EDIT: 2nd thought got rid of junk characters on the screen.
Bill_MI

3 edits

Bill_MI to tmr250z

MVM

to tmr250z
Hey! This stuff is fun but I have the base MAC (for LAN) on the sticker on the bottom of both my units! AFAIK, wireless MAC is the LAN MAC + 2.

I'm wondering if you did some very special technique to change the MAC in the CFE area. That would explain why clearing NVRAM didn't work. I like the lock OpenWrt puts on inadvertently writing to CFE and never went there.

CFE, also known as PMON, is the semi-permanent boot code area of flash not altered by "normal" firmware changes.
tmr250z
join:2009-02-25
Southeast MI

1 edit

tmr250z

Member

Thanks for your help so far, I really appreciate it.

I didn't change the LAN mac address, and as far as I can tell, you can't change it in Tomato. The ones that I altered were the WAN mac address and the Wireless mac address. They are displayed in the Status->Overview section of Tomato. Here's a link on the Virtual GUI of what I'm talking about: »lampiweb.com/tomato/stat ··· ndex.htm
Those are the ones that I want to set back to the original addresses.

I made the changes to them in the Advanced->MAC Address section, as illustrated here: »lampiweb.com/tomato/adva ··· -mac.htm
All I did was change a few of the numbers, left everything else as it was and clicked save. Then I rebooted my modem, router, and computer.

And you're right, the LAN mac address is on the bottom of the router. It is the same one I have in Tomato. It looks like this:

xx:xx:xx:xx:xx:D9

Angralitux
join:2004-05-20
DO

Angralitux to tmr250z

Member

to tmr250z
usually is written on the underside of the device.

Bill_MI
Bill In Michigan
MVM
join:2001-01-03
Royal Oak, MI
TP-Link Archer C7
Linksys WRT54GS
Linksys WRT54G v4

Bill_MI to tmr250z

MVM

to tmr250z
said by tmr250z:

It is the same one I have in Tomato. It looks like this:

xx:xx:xx:xx:xx:D9
Whoa, back up...

If your LAN MAC is: xx:xx:xx:xx:xx:D9
Then your WAN MAC default should be: xx:xx:xx:xx:xx:DA
And Wireless: xx:xx:xx:xx:xx:DB

Sorry it's in HEX, something I didn't mention. See if that makes sense with your settings, now.
tmr250z
join:2009-02-25
Southeast MI

tmr250z

Member

I guess third time's the charm!

I cleared the NVRAM and held the reset button for 60sec then rebooted and this time it worked! The mac addresses are back to their originals, looking just like you said they would above.

Pretty strange it took 3 resets for it to work, but it has, and I'm relieved...finally.

Thanks for the help.