diff --git a/gns3server/modules/dynamips/nodes/router.py b/gns3server/modules/dynamips/nodes/router.py
index 16045537..aff7683b 100644
--- a/gns3server/modules/dynamips/nodes/router.py
+++ b/gns3server/modules/dynamips/nodes/router.py
@@ -113,7 +113,9 @@ class Router(BaseVM):
             if self._aux is not None:
                 self._aux = self._manager.port_manager.reserve_tcp_port(self._aux)
             else:
-                self._aux = self._manager.port_manager.get_free_tcp_port()
+                allocate_aux = self.manager.config.get_section_config("Dynamips").getboolean("allocate_aux_console_ports", False)
+                if allocate_aux:
+                    self._aux = self._manager.port_manager.get_free_tcp_port()
         else:
             log.info("Creating a new ghost IOS instance")
             if self._console:
diff --git a/gns3server/schemas/dynamips_vm.py b/gns3server/schemas/dynamips_vm.py
index 304bcc65..32e9dad5 100644
--- a/gns3server/schemas/dynamips_vm.py
+++ b/gns3server/schemas/dynamips_vm.py
@@ -768,7 +768,7 @@ VM_OBJECT_SCHEMA = {
         },
         "aux": {
             "description": "auxiliary console TCP port",
-            "type": "integer",
+            "type": ["integer", "null"],
             "minimum": 1,
             "maximum": 65535
         },