NAT node can use the VMware NAT

On Windows and Mac OS this allow the NAT node to use the
VMware nat (it's always vmnet8). On Linux we still use the
libvirt NAT

gns3server/compute/builtin/nodes/nat.py

@@ -30,14 +30,21 @@ class Nat(Cloud):
     """
 
     def __init__(self, *args, **kwargs):
-        if "virbr0" not in [interface["name"] for interface in gns3server.utils.interfaces.interfaces()]:
-            raise NodeError("virbr0 is missing. You need to install libvirt")
+
+        if sys.platform.startswith("linux"):
+            if "virbr0" not in [interface["name"] for interface in gns3server.utils.interfaces.interfaces()]:
+                raise NodeError("virbr0 is missing. You need to install libvirt")
+            interface = "virbr0"
+        else:
+            if "vmnet8" not in [interface["name"] for interface in gns3server.utils.interfaces.interfaces()]:
+                raise NodeError("vmnet8 is missing. You need to install VMware or use the NAT node on GNS3 VM")
+            interface = "vmnet8"
 
         ports = [
             {
                 "name": "nat0",
                 "type": "ethernet",
-                "interface": "virbr0",
+                "interface": interface,
                 "port_number": 0
             }
         ]
@@ -54,7 +61,7 @@ class Nat(Cloud):
 
     @classmethod
     def is_supported(self):
-        return sys.platform.startswith("linux")
+        return True
 
     def __json__(self):
         return {