How to fix changing MAC address for a network interface or for a bonding interface after each reboot?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 4. (RHEL 4)
  • Red Hat Enterprise Linux 5. (RHEL 5)
  • Red Hat Enterprise Linux 6. (RHEL 6)
  • Red Hat Enterprise Linux 7. (RHEL 7)
  • Red Hat Enterprise Linux 8. (RHEL 8)

Issue

  • The Network Interface MAC address is changing after each reboot.
  • How to assign a permanent MAC address to the bonding interface in RHEL ?
  • Force the bond interface to take a MAC address of the slave.

Resolution

Assigning permanent MAC address for an Ethernet interface.

Please keep in mind that ethX style naming will not work on RHEL 7 and later. this is described here:

If you are not trying to rename your network devices to ethX style, please see below resolution.

  • Add MACADDR= directive and specify the required MAC address to the /etc/sysconfig/network-scripts/ifcfg-ethX network configuration. So that this value will be taken as the permanent MAC address of the network interface. If HWADDR= directive is present in the network configuration file then make sure to replace it with MACADDR= directive and its corresponding value as follows:
# cat /etc/sysconfig/network-scripts/ifcfg-eth1  
DEVICE=eth1  
BOOTPROTO=dhcp  
HWADDR=00:17:a4:77:09:20  
ONBOOT=yes  
TYPE=Ethernet  
USERCTL=no  
IPV6INIT=no  
PEERDNS=yes
NM_CONTROLLED=no

The HWADDR directive is changed with MACADDR :

# cat /etc/sysconfig/network-scripts/ifcfg-eth1
DEVICE=eth1  
BOOTPROTO=dhcp  
MACADDR=00:17:a4:77:77:25  
ONBOOT=yes  
TYPE=Ethernet  
USERCTL=no  
IPV6INIT=no  
PEERDNS=yes
NM_CONTROLLED=no

Assigning permanent MAC address for a bonding network interface.

  • Forcing a bond to get its MAC address from a specific slave, MACADDR directive has to be added with the MAC address of the required slave to /etc/sysconfig/network-scripts/ifcfg-bondX file.
#  cat /etc/sysconfig/network-scripts/ifcfg-eno1
DEVICE=eno1
NAME=eno1
TYPE=Ethernet
BOOTPROTO=none
ONBOOT=yes
MASTER=bond0
SLAVE=yes
NM_CONTROLLED=no

# cat /etc/sysconfig/network-scripts/ifcfg-eno2
DEVICE=eno2
NAME=eno2
TYPE=Ethernet
BOOTPROTO=none
ONBOOT=yes
MASTER=bond0
SLAVE=yes
NM_CONTROLLED=no

# cat /etc/sysconfig/network-scripts/ifcfg-bond0
DEVICE=bond0
NAME=bond0
TYPE=Bond
MACADDR=a0:36:9f:0f:b1:70
ONBOOT=yes
BOOTPROTO=dhcp
NM_CONTROLLED=no
BONDING_OPTS="mode=active-backup primary=eno1 miimon=100"

  • Note: Red Hat does not support assigning a permanent MAC address to bond interfaces in active-backup mode with the fail_over_mac option set to follow or active.

  • After performing the necessary changes in the network configuration files make sure to reboot the system for the MAC address to take effect.

Diagnostic Steps

HWADDR:<MAC-address>
<MAC-address> is the hardware address of the Ethernet device in the form AA:BB:CC:DD:EE:FF. This directive is useful for machines with multiple NICs to ensure that the interfaces are assigned to the correct device names regardless of the configured load order for each NIC's module, This directive should not be used in conjunction with MACADDR.

MACADDR:<MAC-address>
<MAC-address> is the hardware address of the Ethernet device in the form AA:BB:CC:DD:EE:FF. This directive is used to assign a MAC address to an interface, overriding the one assigned to the physical NIC, This directive should not be used in conjunction with HWADDR.

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