Mac Address Jumping After Reboot

[navneetkakkar]

Dear Team,

We have observed that MAC address of ethernet ports are jumping after reboot i.e. if a certain MAC address is assigned to eth4, after reboot it gets assigned to eth5.

OS is CentOS7.6. Details given below & logs attached.

Please help in resolving.


Before reboot:
[root@ttloladel1 ~]# cat /sys/class/net/eth4/address
34:a2:a2:16:40:e3
[root@ttloladel1 ~]# cat /sys/class/net/eth5/address
cat: /sys/class/net/eth5/address: No such file or directory


After reboot:
[root@ttloladel1 ~]# cat /sys/class/net/eth4/address
cat: /sys/class/net/eth4/address: No such file or directory
[root@ttloladel1 ~]# cat /sys/class/net/eth5/address
34:a2:a2:16:40:e3

[TrevorH]

is CentOS7.6.

7.6 is 3 years out of date and full of bugs that have already been discovered and fixed. Update to 7.9 ASAP.

[tunk]

How does your config files look like, and do you use NetworkManager?

[jlehtone]

Names like eth4 are not presistent, predictable. The system enumerates devices during boot in order that can be random. It is more likely that you get different name for the device that has MAC than 34:a2:a2:16:40:e3 than that MACs would change.

NetworkManager connection defined by installer does bind to interface by the MAC of the interface.
NetworkManager connection defined with nmcli does bind to interface by the name of the interface. That can be changed.

[navneetkakkar]

is CentOS7.6.

7.6 is 3 years out of date and full of bugs that have already been discovered and fixed. Update to 7.9 ASAP.

Can you please share release notes where this bug is resolved.

[pjsr2]

Can you please share release notes where this bug is resolved.

All people providing answers on this forum are CentOS enthusiasts and volunteers. None gets payed for the work of answering your questions. So there is some work you need to do yourself....

The only supported version of CentOS-7 is the latest minor release. The people on this forum run the latest version. They cannot investigate problems that occur on older and no longer supported versions. Again, we are all volunteers.

Only the latest minor revision of CentOS-7 receives security updates. Older minor versions do not get updates. Your 7.6 has not received security updates for several years. Using that version is irresponsible with today's level of internet crime. As a volunteer on this forum, I don't want to support that kind of stupidity (and even if you would pay me, I still don't want to support that stupidity). If you really have to run an older version like 7.6 and thus need security fixes, you should use RHEL 7.x and pay for a valid subscription from RedHat.

As jlehtone explained in his answer, the cause of the problem is that the eth* network device names are not consistent. Therefor this naming convention has been deprecated and replaced by a new naming standard. This is explained in the release notes of CentOS-7. You can find an in-depth explanation in https://access.redhat.com/documentation ... ice_naming.

[TrevorH]

Can you please share release notes where this bug is resolved.

I did not say this bug was resolved. What I said is "7.6 is 3 years out of date and full of bugs that have already been discovered and fixed. Update to 7.9 ASAP". This problem may be one of the several thousand that have been fixed between 7.6 and 7.9 but we do not keep track of them and do not test so I cannot tell you if it is fixed or not.

However, you need to be on 7.9 for very good reasons - among them security and bug fixes - and you should make it so ASAP.

[navneetkakkar]

Can you please share release notes where this bug is resolved.

I did not say this bug was resolved. What I said is "7.6 is 3 years out of date and full of bugs that have already been discovered and fixed. Update to 7.9 ASAP". This problem may be one of the several thousand that have been fixed between 7.6 and 7.9 but we do not keep track of them and do not test so I cannot tell you if it is fixed or not.

However, you need to be on 7.9 for very good reasons - among them security and bug fixes - and you should make it so ASAP.

Thanks!