How Ssh Works - ZyXEL Communications UAG5100 User Manual

Figure 291 SSH Communication Over the WAN Example
A

41.8.1 How SSH Works

The following figure is an example of how a secure connection is established between two remote
hosts using SSH v1.
Figure 292 How SSH v1 Works Example
Host Identification
1
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.
Encryption Method
2
Once the identification is verified, both the client and server must agree on the type of encryption
method to use.
Chapter 41 System
UAG5100 User's Guide
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