Merge 5aee6a9 into 094a60d

napalm_ios/ios.py

@@ -19,6 +19,7 @@
 import re
 import os
 import uuid
+import socket
 import tempfile
 
 from netmiko import ConnectHandler, FileTransfer, InLineTransfer
@@ -145,6 +146,18 @@ def _send_command(self, command):
 
     def is_alive(self):
         """Returns a flag with the state of the SSH connection."""
+        null = chr(0)
+        try:
+            # Try sending ASCII null byte to maintain
+            #   the connection alive
+            self.device.send_command(null)
+        except (socket.error, EOFError):
+            # If unable to send, we can tell for sure
+            #   that the connection is unusable,
+            #   hence return False.
+            return {
+                'is_alive': False
+            }
         return {
             'is_alive': self.device.remote_conn.transport.is_active()
         }