vCD : Change SSH Session Idle timeout of vCloud Director Appliance.

Its bit annoying that the SSH connection to vCloud DIrector Appliance get cut off for just idling for a short time. So we may want to tweak the ssh configuration of vCD appliance to keep the connection alive for longer period.
The following two properties of SSHD define how long the SSH session should stay though there is no input received from the client.


Please click here fore more details.

Sets the number of client alive messages which may be sent without sshd(8) receiving any messages back from the client. If this threshold is reached while client alive messages are being sent, sshd will disconnect the client, terminating the session. It is important to note that the use of client alive messages is very different from TCPKeepAlive. The client alive messages are sent through the encrypted channel and therefore will not be spoofable. The TCP keepalive option enabled by TCPKeepAlive is spoofable. The client alive mechanism is valuable when the client or server depend on knowing when a connection has become inactive.
The default value is

If ClientAliveInterval is set to 15, and ClientAliveCountMax is left at the default, unresponsive SSH clients will be disconnected after approximately 45 seconds.

Sets a timeout interval in seconds after which if no data has been received from the client, sshd(8) will send a message through the encrypted channel to request a response from the client. The default is 0, indicating that these messages will not be sent to the client.

Please follow the steps below to increase the timeout value to 4 hours.
1. Opeh sshd config file.

2. You can see that ‘clientalivecountmax’ is set to 2

3. Let us change it to 0. And define 240m the value for ‘clientaliveinterval’

4. Save the change and restart the SSHD service.
5. Confirm that the values are changed by executing the command ‘sshd -T | grep client’. The value for clientaliveinterval will be in seconds (240m*60=14400s)