ZyXEL Communications UAG2100 - 40.8.1 How SSH Works

Chapter 40 System
UAG2100 User’s Guide
384
Figure 264 SSH Communication Over the WAN Example
40.8.1 How SSH Works
The following figure is an example of how a secure connection is established between two remote
hosts using SSH v1.
Figure 265 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.
2 Encryption Method
Once the identification is verified, both the client and server must agree on the type of encryption
method to use.
A