MAC address

[Pocster]

I always thought these were unique.

But it would seem not. 2 raspberry pi's - same mac address. I've rebooted router/switch - still shows the same!!!. I want to give a unique fixed IP to each one ( based on the supposed unique IP address ) but it would seem I can't. Even unplugged one; reboot everything - still the same MAC address!. I thought the whole point of MAC was unique - what do I do!!!????

Edited November 25, 2021 by pocster

[Pocster]

I should point out when I 'swap' between these 2 it's the same physically connection on the switch. But that shouldn't matter should it?. Google isn't helping me 

[Dan F]

You need to do some spoofing! Does this not help?  https://pimylifeup.com/raspberry-pi-mac-address-spoofing/

[SteamyTea]

You can set the IP address up on each Pi in software, or use a hostname.

Edited November 25, 2021 by SteamyTea

[Pocster]

1 minute ago, SteamyTea said:

You can set the IP address up on each Pi in software, or use a hostname.

I know that. But it's a bit tricky when multiple PI's have the same MAC address

[MJNewton]

How are you discovering the MAC addresses? On the Pi's themselves (running ifconfig or similar) or is it from the router's view of the world? If the latter then it is likely getting confused and/or showing misleading information. The MAC addresses *will* be unique so keep persisting...

[SteamyTea]

what sort of Pi is it, then if I have one similar on my network, can see if it is the same as mine.

 

[Pocster]

23 minutes ago, MJNewton said:

How are you discovering the MAC addresses? On the Pi's themselves (running ifconfig or similar) or is it from the router's view of the world? If the latter then it is likely getting confused and/or showing misleading information. The MAC addresses *will* be unique so keep persisting...

Yeah I detect router / switch are getting confused . But even powering off one pi . Reboot router / switch still shows same MAC address on different pi ! ?

Edited November 25, 2021 by pocster

[Pocster]

17 minutes ago, SteamyTea said:

what sort of Pi is it, then if I have one similar on my network, can see if it is the same as mine.

 

It was a zero - though I have all variations ??

[MJNewton]

Does the router allow you to enter the MAC addresses manually? What router is it?

[SteamyTea]

3 minutes ago, pocster said:

It was a zero

Here is my MAC

 

00:e0:2d:1a:23:0a
 

[epsilonGreedy]

26 minutes ago, MJNewton said:

How are you discovering the MAC addresses? On the Pi's themselves (running ifconfig or similar) or is it from the router's view of the world? If the latter then it is likely getting confused and/or showing misleading information. The MAC addresses *will* be unique so keep persisting...

 

I thought the MAC address was fused into a network chip at fabrication time so could a procedural error in the fab plant cause this problem?

[MJNewton]

They're all going to be different, otherwise you wouldn't be able to use them on the same network.

[Pocster]

Just now, MJNewton said:

They're all going to be different, otherwise you wouldn't be able to use them on the same network.

Yeah I know - but something is confused 

[Pocster]

2 minutes ago, SteamyTea said:

Here is my MAC

 

00:e0:2d:1a:23:0a
 

Same as mine ??????

[MJNewton]

Just now, epsilonGreedy said:

 

I thought the MAC address was fused into a network chip at fabrication time so could a procedural error in the fab plant cause this problem?

 

In theory, I suppose anything is possible. In practice it's not going to be the case. Occam's Razor suggests it is almost certainly a router issue, not least given the majority are built down to a price and are full of bugs.

[epsilonGreedy]

1 minute ago, MJNewton said:

 

In theory, I suppose anything is possible. In practice it's not going to be the case. Occam's Razor suggests it is almost certainly a router issue, not least given the majority are built down to a price and are full of bugs.

 

Ok. I will stick to my specialist subjects namely software and climate change science.

[SteamyTea]

6 minutes ago, pocster said:

Same as mine

 

Here is the address on another one, but an old one.

 

b8:27:eb:2c:9d:dd 

[MJNewton]

7 minutes ago, pocster said:

Same as mine ??????

 

In case you were being serious there (hey, you never know! ;-)) are there any similarities between your setups e.g. same OSs, perhaps one built the Pis for the other etc? MAC addresses can be changed and it might well be the case that your OSs are changing them (to a fixed value, which is a bad idea).

[Pocster]

5 minutes ago, SteamyTea said:

 

Here is the address on another one, but an old one.

 

b8:27:eb:2c:9d:dd 

Same as mine ???? ( I am joking btw !!! )

[MJNewton]

I'm Brian!

 

(And so if my wife!)

[SteamyTea]

8 minutes ago, pocster said:

Same as mine ???? ( I am joking btw !!! )

You can still use and abuse my MAC, just wipe it clean after.

[Pocster]

This was driving me mad!

So I boot 1 raspberry pi at a time. It gets whatever IP address the DHCP server decides. SSH into it and edit dhcpd.conf (I think ). Few lines to get it a fixed IP address ( for everything else I set the fixed IP off the MAC in the router - as it's simpler ).

Have to do it this way - otherwise I can't tell what the hell's going on!. But as others have said all devices MUST have a unique Mac address when manufactured .....

Edited November 26, 2021 by pocster

[Mr Punter]

Maybe you are just getting the MAC address of the router.

[SteamyTea]

Why not use a host name to SSH into.

 

You can, if you want, give it a number.