Some embodiments provide a method for monitoring the status of a network connection between first and second host computers. The method is performed in some embodiments by a tunnel monitor executing on the first host computer that also separately executes a machine, where the machine uses a tunnel to send and receive messages to and from the second host computer. The method establishes a liveness channel with the machine to iteratively determine whether the first machine is operational. The method further establishes a monitoring session with the second host computer to iteratively determine whether the tunnel is operational. When a determination is made through the liveness channel that the machine is no longer operational, the method terminates the monitoring session with the second host computer. When a determination is made that the tunnel is no longer operational, the method notifies the machine through the liveness channel.