How Ssh Works - ZyXEL Communications ZyWall ATP series User Manual

Figure 489 SSH Communication Over the WAN Example

37.8.1 How SSH Works

The following figure is an example of how a secure connection is established between two remote hosts
using SSH v1.
Figure 490 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 37 System
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