This can, e.g., be used to insert new commands in sessions authenticated by one-time passwords. A consequence is that no security method based on purely authenticating the user is safe. Furthermore, routing spoofing can be used to bring almost any connection in the Internet to a location where it can be attacked. Encryption and cryptographic authentication and integrity protection are required to secure networks and computer systems. SSH uses strong cryptographic algorithms to achieve these goals.
Ease of use is critical to the acceptance of a piece of software.
SSH has gained very wide acceptance. Its users include top universities, research laboratories, banks, major corporations, and numerous smaller companies and individuals. The software consists of a number of programs. This listens for connections from client machines, and whenever it receives a connection, it performs authentication and starts serving the client. This is the client program used to log into another machine or to execute commands on the other machine.