ZyXEL Communications NBG410W3G - Manual (Page 268)

Chapter 15 Remote Management
NBG410W3G Series User’s Guide
268
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.
15.7 SSH Implementation on the ZyXEL Device
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.
15.7.1 Requirements for Using SSH
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.
Data Transmission
Authentication Pass / Fail
Password / User name
Encryption method to use
Session Key
Host Identification Pass / Fail
Host Key, Server Key
Connection request
SSH Server
SSH Client