Prevent users to add links to running Qemu VMs and start a capture on running VirtualBox VMs.

gns3server/modules/virtualbox/virtualbox_vm.py

@@ -851,6 +851,7 @@ class VirtualBoxVM(BaseVM):
                                                                                                      adapter_number=adapter_number))
         return nio
 
+    @asyncio.coroutine
     def start_capture(self, adapter_number, output_file):
         """
         Starts a packet capture.
@@ -865,6 +866,10 @@ class VirtualBoxVM(BaseVM):
             raise VirtualBoxError("Adapter {adapter_number} doesn't exist on VirtualBox VM '{name}'".format(name=self.name,
                                                                                                             adapter_number=adapter_number))
 
+        vm_state = yield from self._get_vm_state()
+        if vm_state == "running" or vm_state == "paused" or vm_state == "stuck":
+            raise VirtualBoxError("Sorry, packet capturing on a started VirtualBox VM is not supported.")
+
         nio = adapter.get_nio(0)
         if nio.capturing:
             raise VirtualBoxError("Packet capture is already activated on adapter {adapter_number}".format(adapter_number=adapter_number))