#1002656 bridge-utils: bridge_hw: add random option like for ifupdown hwaddress

Package:
bridge-utils
Source:
bridge-utils
Description:
Utilities for configuring the Linux Ethernet bridge
Submitter:
Martin-Éric Racine
Date:
2026-01-10 11:39:15 UTC
Severity:
normal
#1002656#5
Date:
2021-12-26 19:56:29 UTC
From:
To:
It would be desirable for bridge_hw to be able to generate a random MAC address as per ifupdown's generic hwaddress syntax.

Possible values for bridge_hw would thereafter be:

MAC
interface
random

MAC|interface would continue working as currently, while random would generate a random MAC address for the bridge.

- -- System Information:
Debian Release: 11.2
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable-debug'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 5.10.0-10-amd64 (SMP w/8 CPU threads)
Locale: LANG=fi_FI.utf8, LC_CTYPE=fi_FI.utf8 (charmap=UTF-8), LANGUAGE=fi:en
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages bridge-utils depends on:
ii  libc6  2.31-13+deb11u2

bridge-utils recommends no packages.

Versions of packages bridge-utils suggests:
ii  ifupdown  0.8.36

- -- Configuration Files:
/etc/default/bridge-utils changed:
BRIDGE_HOTPLUG=yes


- -- no debconf information
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#1002656#10
Date:
2022-10-06 22:01:17 UTC
From:
To:
Hi!

I don't know if I get this right or not... if you don't want to specify a
MAC or get it from an interface... then you better not assign any MAC and so
systemd will do his thing and assign a "random" one.

I really don't think that the code on bridge-utils should generate such a
random MAC, systemd already causes a lot of trouble by overriding the
address that the kernel would select, I don't think we need another actor
here.

Can you justify your request?

Otherwise I'll close the bug.

Regards.
#1002656#15
Date:
2022-10-06 22:01:17 UTC
From:
To:
Hi!

I don't know if I get this right or not... if you don't want to specify a
MAC or get it from an interface... then you better not assign any MAC and so
systemd will do his thing and assign a "random" one.

I really don't think that the code on bridge-utils should generate such a
random MAC, systemd already causes a lot of trouble by overriding the
address that the kernel would select, I don't think we need another actor
here.

Can you justify your request?

Otherwise I'll close the bug.

Regards.
#1002656#20
Date:
2022-10-07 04:41:34 UTC
From:
To:
The kernel using the MAC of a real device, if none is specified, is
precisely what we wanna avoid.  Systemd is not involed.

Martin-Éric
#1002656#25
Date:
2022-10-07 20:34:17 UTC
From:
To:
Like I said, if we don't specify the mac address systemd will set up a fake
one for us, so... systemd is involved and the kernel is not allowed to use a
real one, that's why I said that bridge-utils shouldn't do a thing about
this.

Regards.
#1002656#30
Date:
2023-06-10 03:04:28 UTC
From:
To:
No, systemd does not set up a fake MAC address. Rather, the MAC
address of any PHY attached to the bridge is used if no MAC address is
specified.

Martin-Éric
#1002656#35
Date:
2023-06-11 06:23:47 UTC
From:
To:
On Sat, Jun 10, 2023 at 6:04 AM Martin-Éric Racine <martin-eric.racine@iki.fi> wrote:

Btw, I vaguely recall you having had to modify the code to stop
showing the IPv6 local-link of wireless devices. Is that correct? If
yes, simply reverting this to have all devices show IPv6 local-link
would be a suitable fix. It would of course introduce a shift in
expected behavior from Bulleseye, but it would at least act
consistently for all interfaces.

Martin-Éric
#1002656#40
Date:
2026-01-10 10:08:08 UTC
From:
To:
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