Support running duration settings

[WangXiangUSTC]

For example, the network attack may partition all host, so that can't connect to it and can't recover it anymore. So need to add a running duration settings, network attack will recover automatically.

[alissa-tung]

That would be useful. I am wondering how can I terminate partition status or is there any workaround for duration settings. Besides, attacking a undefined device won't leads to error. Is this work as expected?