SSH Reference Manual

Components of the SSH2 Software Package
The SSH2 software package consists of the following components:
• The SSH2 component is the central component of the implementation. Depending on the mode it is started in, it
can serve different purposes:
o It implements a server process for the SSH2 protocol. It listens for incoming connections on a specific
TCP/IP port (typically port 22), authenticates the user and the service and then spawns other processes it
communicates with.
o It is opened by the SSHCOM component to maintain the SSH configuration database.
o It is opened by the SFTP or SSH client components to initiate Shell or SFTP-based file transfers to other
platforms running an SSH daemon.
The SSH2 component accesses a user database that contains the following entries for incoming SFTP
connections:
o remote user names
o the mapping of remote user names to Guardian system users
o user’s public keys
o user’s credentials on the system
o selected status information, such as the last time a user accessed the system
• The SSHOSS component implements a Secure Shell client running under OSS to connect to a remote SSH
daemon. It provides Secure Shell sessions as well as TCP and FTP port forwarding capabilities.
• The SSH component implements a Secure Shell client running under Guardian to connect to a remote SSH
daemon. It provides Secure Shell sessions as well as TCP and FTP port forwarding capabilities.
• The SFTPSERV component is started by SSH2 for each SFTP client that connects to SSH2 components. The
SFTPSERV component then handles the file I/O associated with the file transfers initiated by the SFTP client.
Because SFTPSERV is started by the SSH2 component, configuration of SFTPSERV is implicit by the
configuration of the SSH2 component.
• The SFTPOSS component implements an SFTP client running under the OSS personality.
• The SFTP component implements an SFTP client running under the Guardian personality.
• The SSHCOM component allows the maintenance of the SSH user database. To do so, it communicates with
the SSH2 component.
• The PAUTH component is used by SSH2 for authenticating user passwords against the system user base.
• The STN component is a pseudo TTY server providing full screen shell access to remote SSH clients.
• The SCPOSS component is the scp server implementation. It is started on request of a remote scp client via
shell command. The scp client on Guardian/OSS has not been added yet.
HP NonStop SSH Reference Manual Introduction • 27