3Com Switch 8800 Advanced Software V5 Configuration Guide

936 CHAPTER 72: CONFIGURING SSH VERSION 2.0
Figure 279 Establish an SSH channel through WAN
n
■ Currently, when acting as an SSH server, the device supports two SSH versions:
SSH2 and SSH1. When acting as an SSH client, the device supports SSH2 only.
■ Unless otherwise noted, the “SSH” term in this document refers to SSH2.
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.
Figure 280 Encryption and decryption
Key-based algorithm is usually classified into symmetric key algorithm and
asymmetric key algorithm.
Asymmetric Key
Algorithm
Asymmetric key algorithm means that a key pair exists at both ends. The key pair
consists of a private key and a public key. The public key is effective for both ends,
while the private key is effective only for the local end.
Asymmetric key algorithm encrypts data using the public key and decrypts the
data using the private key, thus ensuring data security.
Server
Server
WAN
SSH server
Host A
Laptop
SSH client
Laptop
Host C
Host B
Switch
Local LAN
Remote LAN
Encryption
Key
Decryption
Cipher text
Plain text
Key
Plain textEncryption
Key
Decryption
Cipher text
Plain text
Key
Plain text