H3C Technologies H3C WX3000 Series Unified Switches - Manual (Page 473)

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SSH Configuration
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The term switch used throughout this document refers to a switching device in a generic sense or
the switching engine of a WX3000 series.
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The sample output information in this manual was created on the WX3024. The output information
on your device may vary
SSH Overview
Introduction to SSH
Secure Shell (SSH) is a protocol that provides secure remote login and other security services in
insecure network environments. In an SSH connection, data are encrypted before being sent out and
decrypted after they reach the destination. This prevents attacks such as plain text password
interception. Besides, SSH also provides powerful user authentication functions that prevent attacks
such as DNS and IP spoofing.
SSH adopts the client-server model. The device can be configured as an SSH client or an SSH server.
In the former case, the device establishes a remote SSH connection to an SSH server. In the latter case,
the device provides connections to multiple clients.
Furthermore, SSH can also provide data compression to increase transmission speed, take the place of
Telnet or provide a secure “channel” for FTP.
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Currently, the device that serves as an SSH server supports two SSH versions: SSH2 and SSH1,
and the device that serves as an SSH client supports only SSH2.
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Unless otherwise noted, SSH refers to SSH2 throughout this document.
Algorithm and Key
Algorithm is a set of transformation rules for encryption and decryption. Information without being
encrypted is known as plain text, while information that is encrypted is known as cipher text. Encryption
and decryption are performed using a string of characters called a key, which controls the
transformation between plain text and cipher text, for example, changing the plain text into cipher text or
cipher text into plain text.