The Global Gen World

The SSH-2 or the revised Secure Shell protocol has a clean internal architecture made up of well-separated layers. The transport layer handles initial key exchange and server authentication and thereby sets up encryption, compression and integrity verification. The user authentication layer handles client authentication and provides various authentication methods. However, it should be noted that authentication is client-driven thus a password prompt may be initiated by an SSH client rather than the server.

The connection layer defines the concept of channels, channel requests and global requests using SSH services that are provided. SSH-2’s open architecture allows for substantial flexibility so that SSH can be used for a variety of purposes beyond the Secure Shell.