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SSH Keepalives To Prevent Inactivity Timeouts

Add the following settings to your sshd_config file to prevent inactivity timeouts for ssh sessions.

ClientAliveInterval 180
ClientAliveCountMax 3

Sets a timeout interval in seconds after which if no data has
been received from the client, sshd 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.

Sets the number of client alive messages which may be
sent without sshd 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 3. If ClientAliveInterval is
set to 15, and ClientAliveCountMax is left at the default, unresponsive
SSH clients will be disconnected after approximately 45 seconds.

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