Secure Shell is a combination of client
and server software that transparently encrypts and decrypts data flow between
hosts on a network. SSH provides a suite of secure network commands that you
can use in addition to, or in place of, traditional nonsecure network commands
like TELNET and FTP.
Using Secure Shell commands, you create a secure connection between
systems running the Secure Shell client and server software by providing the
following security methods:
Authentication -- Secure Shell servers and clients use an
authentication method to reliably determine each other's identity and the
Data encryption -- Secure Shell servers and clients exchange
encrypted data. Data encryption is transparent to the user.
The Secure Shell Server
A Secure Shell server (SSH server) is a system on which the system manager installs
and runs the Secure Shell server software.
The SSH server accepts and rejects incoming connections to the server
from the SSH clients on remote hosts. The SSH server listens on the port defined
for the TCP/IP SSH service (port 22 by default). When a connection request
occurs, the auxiliary server creates a new server process that controls all
data exchanges over the new connection.
The SSH server provides the following functions:
Secure remote user login
Secure file transfer between remote computers
Remote command execution
For all of these functions, the entire login and data transfer sessions,
including user identification information, are secured through user authentication
and data encryption.
The SCP and SFTP commands
copy files to and from an SSH server.
The SSH command logs in to a remote server
and performs remote command execution (tunnelling).
The SSH key management utilities generate
public-private key pairs and manipulate keys.
These commands and utilities are described in Chapter
NOTE: SSH for OpenVMS software is based on SSH2 software from SSH Communication
Security version 3.2.1. In the OpenVMS implementation, the commands SSH, SCP,
and SFTP mean the same as SSH2,SCP2,
and SFTP2. You can use either set of commands with SSH
for OpenVMS. For more information about these commands, enter the DCL HELP
command. For example: