On 10/30/2015 07:02 AM, Michal Privoznik wrote: I haven't ever used the python bindings for the interface APIs, but if changeBegin is implemented as a method of an interface, that is wrong - virInterfaceChangeBegin() saves all the config for *all* interfaces on the host, so it should instead be a method of the connection. (To be more descriptive, virInterfaceChangeBegin() makes a copy of all network interface config for all interfaces on the host. You can then modify the network config as you wish (add/remove/modify interface configs), then when you're sure the new config works, call virInterfaceChangeCommit() to throw away the snapshotted copy of config. If the host is rebooted without calling virInterfaceChangeCommit(), an initscript (or whatever they call the equivalent in systemd) called during boot will replace the new network config with whatever it was at the time virInterfaceChangeBegin() was called. You can also force this rollback prior to boot by calling virinterfaceChangeRollback() (note that rollback only affects the config files, *not* the current working state of the network)).