[Bug 2104155] Re: systemd-udev interferes with MAC addresses of interfaces

Fri Mar 28 20:03:05 UTC 2025

This is *probably* just the default behavior, i.e.
/usr/lib/systemd/network/99-default.link, kicking in since no MAC
address is initially assigned. Does the MAC actually change each boot,
or does udev assign the same one each boot?

> while we have a permanent Mac configured for that network interface

Where is this happening? How are you configuring this?

Some debug information would be helpful:

1) Debug logs from systemd-udevd:

$ mkdir -p /etc/systemd/system/systemd-udevd.service.d/
$ cat > /etc/systemd/system/systemd-udevd.service.d/debug.conf << EOF
[Service]
Environment=SYSTEMD_LOG_LEVEL=debug
$ reboot

...

$ journalctl -u systemd-udevd.service -b > udev.log

2) udevadm info

$ udevadm info /sys/class/net/ens192 > udevadm-info-ens192.txt

3) Any networkd configs for this device. E.g. files in
/etc/systemd/network/ or /run/systemd/network that are custom (or
generated by netplan) and related to your configuration.

Please attach the above debug output to this bug.

** Changed in: systemd (Ubuntu)
       Status: New => Incomplete

** Also affects: systemd (Ubuntu Jammy)
   Importance: Undecided
       Status: New

** Changed in: systemd (Ubuntu Jammy)
       Status: New => Incomplete

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/2104155

Title:
  systemd-udev interferes with MAC addresses of interfaces

Status in systemd package in Ubuntu:
  Incomplete
Status in systemd source package in Jammy:
  Incomplete

Bug description:
  While configuring a system based on ubuntu 22.04 version , we found
  that a system-d udev rules assign a random mac address to one of the
  network interfaces .

  Kernel version

  uname -a

  5.15.0-25-generic #25-Ubuntu SMP Wed Mar 30 15:54:22 UTC 2022 x86_64
  x86_64 x86_64 GNU/Linux

  Ubunutu version

  root at maglev-master-10-106-0-137:~# lsb_release -a
  No LSB modules are available.
  Distributor ID: Ubuntu
  Description:    Ubuntu 22.04.5 LTS
  Release:        22.04
  Codename:       jammy

  ip addr show output which shows the mac address has been changed

   ens192: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master management state UP group default qlen 1000
      link/ether d2:29:6b:94:be:bd brd ff:ff:ff:ff:ff:ff permaddr 00:50:56:b8:ed:a0
      altname enp11s0

  d2:29:6b:94:be:bd is being randomly assigned while permanent address
  is 00:50:56:b8:ed:a0

  root at maglev-master-10-106-0-137:~# ethtool -P ens192
  Permanent address: 00:50:56:b8:ed:a0

  PID: 1760 (snmpd) changed MAC to 00:00:00:00:00:00
  PID: 1760 (snmpd) changed MAC to 00:00:00:00:00:00
  PID: 15073 (systemd-udevd) changed MAC to d2:29:6b:94:be:bd
  PID: 15073 (systemd-udevd) changed MAC to d2:29:6b:94:be:bd
  PID: 15073 (systemd-udevd) changed MAC to d2:29:6b:94:be:bd
  PID: 15084 (ip) changed MAC to d2:29:6b:94:be:bd
  PID: 15084 (ip) changed MAC to d2:29:6b:94:be:bd

  bpftrace output

  Invoked kprobe:dev_set_mac_address_user with MAC d2:29:6b:94:be:bd
  Stack trace:

          dev_set_mac_address_user+1
          rtnl_setlink+246
          rtnetlink_rcv_msg+349
          netlink_rcv_skb+83
          rtnetlink_rcv+21
          netlink_unicast+538
          netlink_sendmsg+588
          sock_sendmsg+98
          __sys_sendto+275
          __x64_sys_sendto+36
          do_syscall_64+89
          entry_SYSCALL_64_after_hwframe+68

   systemd-udevd(7123)	systemd-udevd(6656)
  Invoked kprobe:dev_set_mac_address with MAC d2:29:6b:94:be:bd
  Stack trace:

          dev_set_mac_address+1
          do_setlink+2217
          rtnl_setlink+246
          rtnetlink_rcv_msg+349
          netlink_rcv_skb+83
          rtnetlink_rcv+21
          netlink_unicast+538
          netlink_sendmsg+588
          sock_sendmsg+98
          __sys_sendto+275
          __x64_sys_sendto+36
          do_syscall_64+89
          entry_SYSCALL_64_after_hwframe+68

   systemd-udevd(7123)	systemd-udevd(6656)
  Invoked kprobe:bond_set_mac_address with MAC d2:29:6b:94:be:bd
  Stack trace:

          bond_set_mac_address+1
          dev_set_mac_address_user+50
          do_setlink+2217
          rtnl_setlink+246
          rtnetlink_rcv_msg+349
          netlink_rcv_skb+83
          rtnetlink_rcv+21
          netlink_unicast+538
          netlink_sendmsg+588
          sock_sendmsg+98
          __sys_sendto+275
          __x64_sys_sendto+36
          do_syscall_64+89
          entry_SYSCALL_64_after_hwframe+68

   ip(7137)	sh(7135)	python3(7013)	twistd3(2045)	web_install_ser(1959)
  Invoked kprobe:dev_set_mac_address with MAC d2:29:6b:94:be:bd
  Stack trace:

          dev_set_mac_address+1
          do_set_master+146
          do_setlink+684
          __rtnl_newlink+1560
          rtnl_newlink+73
          rtnetlink_rcv_msg+349
          netlink_rcv_skb+83
          rtnetlink_rcv+21
          netlink_unicast+538
          netlink_sendmsg+588
          sock_sendmsg+98
          ____sys_sendmsg+590
          ___sys_sendmsg+129
          __sys_sendmsg+98
          __x64_sys_sendmsg+29
          do_syscall_64+89
          entry_SYSCALL_64_after_hwframe+68

   ip(7137)	sh(7135)	python3(7013)	twistd3(2045)	web_install_ser(1959)
  Invoked kprobe:vmxnet3_set_mac_addr with MAC d2:29:6b:94:be:bd
  Stack trace:

          vmxnet3_set_mac_addr+1
          bond_enslave+1521
          do_set_master+146
          do_setlink+684
          __rtnl_newlink+1560
          rtnl_newlink+73
          rtnetlink_rcv_msg+349
          netlink_rcv_skb+83
          rtnetlink_rcv+21
          netlink_unicast+538
          netlink_sendmsg+588
          sock_sendmsg+98
          ____sys_sendmsg+590
          ___sys_sendmsg+129
          __sys_sendmsg+98
          __x64_sys_sendmsg+29
          do_syscall_64+89
          entry_SYSCALL_64_after_hwframe+68

  Not able to understand  why this systemd rule is triggering and
  assigning MAC address randomly while we have a permanent Mac
  configured for that network interface .

  We found this reported issue in systemd .

  https://github.com/systemd/systemd/issues/21185 
  https://github.com/systemd/systemd/commit/6d36464065601f79a352367cf099be8907d8f9aa

   are they reason we are also running into the issue and if so, how do
  we get away from this Other than setting MACAddressPolicy=none ?

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/2104155/+subscriptions