man ssh_config
предполагает, что ServerAliveInterval
- это то, что вы ищете:
ServerAliveInterval
Sets a timeout interval in seconds after which if no data has been received from the server, ssh(1) will send a message through
the encrypted channel to request a response from the server. The default is 0, indicating that these messages will not be sent
to the server, or 300 if the BatchMode option is set. This option applies to protocol version 2 only. ProtocolKeepAlives and
SetupTimeOut are Debian-specific compatibility aliases for this option.