[SOLVED] how to set bridge MAC HW address?

[sdettmer]

Hi,

I have a Debian 11 machine that has something like

iface br0 inet dhcp
    bridge_ports enp3s0
    bridge_hw 52:aa:bb:cc:dd:ee

and it is working

$ ip link show dev br0
9: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 52:aa:bb:cc:dd:ee brd ff:ff:ff:ff:ff:ff

(according to https://wiki.debian.org/BridgeNetworkConnections near "Bridging with a wireless NIC" at "bridge_hw $MAC_ADDRESS_OF_YOUR_WIRELESS_CARD")

Since Proxmox is based on Debian I think the same should work here too. After spending much to much time on strage network traffic I found I need to use hwaddress instead:

iface br0 inet dhcp
    bridge_ports enp3s0
    hwaddress 52:aa:bb:cc:dd:ee

confirming to many (unrelated) examples posted in this forum.

Why do I notice a difference here?
Should I set both "to go sure"? This currently works for me, but since this is guessing I don't like it and I hope someone can explain so that I understand what is the right way and why it is different at all.

PS: some source say bridge_hw should take an interface name were to "copy" the MAC from, like old kernels did. But I'm confused if this would be the case, why it is working on Debian 11 to specific a MAC address but not on Proxmox 7.2.

PPS: I notice that apparently /etc/issue is not updated and tells the wrong IP after changing it, is this intentional?

 

[Richard]

Why do I notice a difference here?
Should I set both "to go sure"? This currently works for me, but since this is guessing I don't like it and I hope someone can explain so that I understand what is the right way and why it is different at all.

PS: some source say bridge_hw should take an interface name were to "copy" the MAC from, like old kernels did. But I'm confused if this would be the case, why it is working on Debian 11 to specific a MAC address but not on Proxmox 7.2.

The difference is caused by ifupdown vs. ifupdown2: Debian 11 default is ifupdown which needs "bridge_hw" as keyword where Proxmox uses per default ifupdown2 which needs "hwaddress" as keyword. You can change this also in Proxmox by

apt install ifupdown

which removes implicitly ifupdown2 (disadvantage: change in network configuration requests a reboot)

PPS: I notice that apparently /etc/issue is not updated and tells the wrong IP after changing it, is this intentional?

When changing the IP /etc/hosts has to be adapted accordingly

 

[sdettmer]

The difference is caused by ifupdown vs. ifupdown2

Wow, thank you so much for your detailed and helpful answer and the tip with /etc/hosts!