After authentication is complete, the user can use Secure Shell, generally by requesting a shell or executing a command. Through the ssh command options, the user can make requests. Requests can include allocating a pseudo-TTY, forwarding X11 connections or TCP/IP connections, or enabling an ssh-agent authentication program over a secure connection.
The basic components of a user session are as follows:
The user requests a shell or the execution of a command, which begins the session mode.
In this mode, data is sent or received through the terminal on the client side. On the server side, data is sent through the shell or a command.
When data transfer is complete, the user program terminates.
All X11 forwarding and TCP/IP forwarding is stopped, except for those connections that already exist. Existing X11 connections and TCP/IP connections remain open.
The server sends an exit status message to the client. When all connections are closed, such as forwarded ports that had remained open, the client closes the connection to the server. Then, the client exits.