From 7065988087720e334b307ddde457f1eefb4de008 Mon Sep 17 00:00:00 2001
From: Julien Duponchelle <julien@gns3.net>
Date: Tue, 30 Aug 2016 18:27:04 +0200
Subject: [PATCH] Raise an error if we use nat and eth1 doesn't exists

Fix #657
---
 gns3server/compute/builtin/nodes/nat.py | 5 +++++
 tests/conftest.py                       | 5 +++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/gns3server/compute/builtin/nodes/nat.py b/gns3server/compute/builtin/nodes/nat.py
index b54e78d6..b2c053f8 100644
--- a/gns3server/compute/builtin/nodes/nat.py
+++ b/gns3server/compute/builtin/nodes/nat.py
@@ -19,6 +19,8 @@ import socket
 from .cloud import Cloud
 from ...error import NodeError
 
+import gns3server.utils.interfaces
+
 
 class Nat(Cloud):
     """
@@ -32,6 +34,9 @@ class Nat(Cloud):
         if socket.gethostname() != "gns3vm":
             raise NodeError("NAT node is supported only on GNS3 VM")
 
+        if "eth1" not in [interface["name"] for interface in gns3server.utils.interfaces.interfaces()]:
+            raise NodeError("eth1 is missing on the GNS3 VM. You need to provide a nat interface as eth1")
+
         self.ports = [
             {
                 "name": "nat0",
diff --git a/tests/conftest.py b/tests/conftest.py
index 2d08f0e6..a3c2d00f 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -322,5 +322,6 @@ def on_gns3vm():
     """
     Mock the hostname to  emulate the GNS3 VM
     """
-    with patch("socket.gethostname", return_value="gns3vm"):
-        yield
+    with patch("gns3server.utils.interfaces.interfaces", return_value=[{"name": "eth0"}, {"name": "eth1"}]):
+        with patch("socket.gethostname", return_value="gns3vm"):
+            yield