Since the private portions of these keys are known only to the server, only the server can decrypt it to obtain the session key. From this point on, all data in this session will be encrypted using the session key before being sent to the other party. This session key lasts only as long as the session does. Therefore, if the client were to disconnect and reconnect, he would generate a different session key. User authentication takes place next.
Local authentication takes place against the locally defined user file.
The host key size and the server key size are paramount in determining how secure the keys are. The RAS 2000 supports upto 2048-bit host and server keys. The practicality of keys larger than that decreased substantially while CPU requirements increased exponentially. As shipped, the RAS 2000 is configured to have the Web server running as well as telnetd and sshd. However, sshd will refuse to run until a host key has been generated, a process that must be started manually.