ZyXEL Communications GS2200 Series, Руководство пользователя

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Chapter 35 Access Control
GS2200 Series User’s Guide
271
35.7.2 SSH Overview
Unlike Telnet or FTP, which transmit data in clear text, SSH (Secure Shell) is a secure
communication protocol that combines authentication and data encryption to provide secure
encrypted communication between two hosts over an unsecured network.
Figure 179
SSH Communication Example
35.7.2.1 How SSH works
The following table summarizes how a secure connection is established between two remote hosts.
Figure 180
How SSH Works
1
Host Identification
The SSH client sends a connection request to the SSH server. The server identifies itself with a host
key. The client encrypts a randomly generated session key with the host key and server key and
sends the result back to the server.
The client automatically saves any new server public keys. In subsequent connections, the server
public key is checked against the saved version on the client computer.