diff --git a/uncloud/hack/net.py b/uncloud/hack/net.py
index 6e2a6ee..30d0c03 100644
--- a/uncloud/hack/net.py
+++ b/uncloud/hack/net.py
@@ -32,6 +32,8 @@ class VXLANBridge(object):
 
         if use_sudo:
             self.config['sudo'] = 'sudo '
+        else:
+            self.config['sudo'] = ''
 
         self.config['vni_dec'] = vni
         self.config['vni_hex'] = "{:x}".format(vni)