Ssh; How Ssh Works; Figure 486 Ssh Communication Over The Wan Example; Figure 487 How Ssh V1 Works Example - ZyXEL Communications ZyWALL USG 300 User Manual

Chapter 45 System

45.7 SSH

You can use SSH (Secure SHell) to securely access the ZyWALL's command line interface.
Specify which zones allow SSH access and from which IP address the access can come.
SSH is a secure communication protocol that combines authentication and data encryption to
provide secure encrypted communication between two hosts over an unsecured network. In
the following figure, computer A on the Internet uses SSH to securely connect to the WAN
port of the ZyWALL for a management session.

Figure 486 SSH Communication Over the WAN Example

45.7.1 How SSH Works

The following figure is an example of how a secure connection is established between two
remote hosts using SSH v1.

Figure 487 How SSH v1 Works Example

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.
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