SINT - Keep SSH connection open with ServerAlive options

# connection settings
ServerAliveInterval 10
ServerAliveCountMax 18
When no data are received send NULL packet every 10 seconds. If there is no response after 18 retries terminate the connection.

ssh_config manpage
              Sets the number of server alive messages (see below) which may be sent without ssh(1) receiving any messages back  from  the  server.   If  this  threshold  is
              reached  while  server  alive  messages  are being sent, ssh will disconnect from the server, terminating the session.  It is important to note that the use of
              server alive messages is very different from TCPKeepAlive (below).  The server alive messages are sent through the encrypted channel and therefore will not  be
              spoofable.   The TCP keepalive option enabled by TCPKeepAlive is spoofable.  The server alive mechanism is valuable when the client or server depend on knowing
              when a connection has become inactive.

              The default value is 3.  If, for example, ServerAliveInterval (see below) is set to 15 and ServerAliveCountMax is left at the default, if  the  server  becomes
              unresponsive, ssh will disconnect after approximately 45 seconds.  This option applies to protocol version 2 only.

              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.  This option applies to protocol  version
              2 only.

author: (Jaroslav Petráš)

date: Wed, 15 Aug 2012 11:16:02 +0000