code: func CreateMasterDummy(t *testing.T, master string) {
  	// ip link add <dummy_name> type dummy
  	icmd.RunCommand("ip", "link", "add", master, "type", "dummy").Assert(t, icmd.Success)
  	icmd.RunCommand("ip", "link", "set", master, "up").Assert(t, icmd.Success)
  }
docs: // CreateMasterDummy creates a dummy network interface