Use RAW sockets by default on Linux.

gns3server/compute/base_node.py

@@ -622,7 +622,7 @@ class BaseNode:
                 i += 1
 
     @asyncio.coroutine
-    def _add_ubridge_ethernet_connection(self, bridge_name, ethernet_interface, block_host_traffic=True):
+    def _add_ubridge_ethernet_connection(self, bridge_name, ethernet_interface, block_host_traffic=False):
         """
         Creates a connection with an Ethernet interface in uBridge.
 

gns3server/compute/builtin/nodes/cloud.py

@@ -210,7 +210,7 @@ class Cloud(BaseNode):
         if port_info["type"] in ("ethernet", "tap"):
 
             if sys.platform.startswith("win"):
-                yield from self._add_ubridge_ethernet_connection(bridge_name, port_info["interface"], block_host_traffic=False)
+                yield from self._add_ubridge_ethernet_connection(bridge_name, port_info["interface"])
 
             else: