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Chapter 35 Access Control

GS2200-8/24 User’s Guide

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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.