Thomas Haller authored
Long ago before commit 1b49f941, NetworkManager did not touch the MAC address at all. Since 0.8.2 NetworkManager would modify the MAC address, and eventually it would reset the permanent MAC address of the device. This prevents a user from externally setting the MAC address via tools like macchanger and rely on NetworkManager not to reset it to the permanent MAC address. This is considered a security regression in bgo#708820. This only changed with commit 9a354cdc and 1.4.0. Since then it is possible to configure "cloned-mac-address=preserve", which instead uses the "initial" MAC address when the device activates. That also changed that the "initial" MAC address is the address which was externally configured on the device as last. In other words, the "initial" MAC address is picked up from external changes, unless it was NetworkManager itself who configured the address when activating a connection. However, in absence of an explicit configuration the default for "cloned-mac-address" is still "permanent". Meaning, the user has to explicitly configure that NetworkManager should not touch the MAC address. It makes sense to change the upstream default to "preserve". Although this is a change in behavior since 0.8.2, it seems a better default. This change has the drastic effect that all the existing connections out there with "cloned-mac-address=$(nil)" change behavior after upgrade. I think most users won't notice, because their devices have the permanent address set by default anyway. I would think that there are few users who intentionally configured "cloned-mac-address=" to have NetworkManager restore the permanent address. https://bugzilla.gnome.org/show_bug.cgi?id=770611fae5ecec
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