Using an OpenSSH server's ClientAliveInterval,
it is possible for the ssh server to send periodic "keep alive"
messages to the ssh client, keeping the connection open indefinitely.
This is useful when a firewall or other packet filtering device drops
idle connections after a certain period of time. Note that this is
different from the KeepAlive
directive in ssh_config.
From the sshd_config manpage:
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. This option applies to protocol version 2 only.
Example (send "keep alive" messages every 5 minutes) on Red Hat Linux:
1. Add ClientAliveInterval 300
2. Reload the sshd
server configuration with /sbin/service
Note: you may want to configure the ClientAliveCountMax value in sshd_config to set the number of
times that "keep alive" messages are sent. If ClientAliveCountMax number of "keep
alive" messages are not acknowledged by the ssh client, the connection
is terminated by the ssh server. The default value of 3 should be
sufficient for most users.
Back to brandonhutchinson.com.
Last modified: 12/02/2003