ZyXEL Communications NBG410W3G Series User Manual

Chapter 15 Remote Management

NBG410W3G Series User’s Guide

Figure 167   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.

2 Encryption Method

Once the identification is verified, both the client and server must agree on the type of 
encryption method to use.

3 Authentication and Data Transmission

After the identification is verified and data encryption activated, a secure tunnel is 
established between the client and the server. The client then sends its authentication 
information (user name and password) to the server to log in to the server.

Your ZyXEL Device supports SSH version 1.5 using RSA authentication and three encryption 
methods (DES, 3DES and Blowfish). The SSH server is implemented on the ZyXEL Device 
for remote management and file transfer on port 22. Only one SSH connection is allowed at a 
time.

You must install an SSH client program on a client computer (Windows or Linux operating 
system) that is used to connect to the ZyXEL Device over SSH.