Giorgio,
As Michael stated, SSH timeout has nothing to do with the sessionTimeout attribute for a Delphix connection.
Rather, the parameters "clientAliveInterval" and "clientAliveCountMax" are set within the "sshd_config" file on a UNIX/Linux server or host, generally located within the "/etc/ssh" directory and in the "C:\Program Files\OpenSSH\etc\
folder" on Windows.
Documentation about these parameters excerpted from the UNIX/Linux "man" page documentation on "sshd_config"...
ClientAliveCountMax Sets the number of client alive messages (see below) 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 ses- sion. It is important to note that the use of client alive mes- sages is very different from TCPKeepAlive (below). The client alive messages are sent through the encrypted channel and there- fore will not be spoofable. The TCP keepalive option enabled by TCPKeepAlive is spoofable. The client alive mechanism is valu- able when the client or server depend on knowing when a connec- tion has become inactive. The default value is 3. If ClientAliveInterval (see below) is set to 15, and ClientAliveCountMax is left at the default, unre- sponsive ssh clients will be disconnected after approximately 45 seconds. ClientAliveInterval 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.
Putty's SO_KEEPALIVE setting might be worth trying, but I'm not certain that it overrides the settings inherited from the server. The Putty documentation describes how to set SO_KEEPALIVE for a new session, an existing session, and for all future sessions.
The Delphix "hostchecker" for UNIX/Linux platforms will warn about "clientAliveInterval" and "clientAliveCountMax" settings, as documented
online here (see option "-7"), and Delphix Engine 4.2 and above will also automatically create warning faults if settings are detected.
Hope this helps!