ZyXEL Communications ZyXEL Dimension GS-4012F - Manual (Page 211)

GS-4012F/4024 User’s Guide
210 Chapter 33 Access Control
33.4 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 128 SSH Communication Example
33.5 How SSH works
The following table summarizes how a secure connection is established between two remote
hosts.
Figure 129 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.