ZyXEL Communications ES-2024A - How SSH Works; Figure 70 SSH Communication Example; Figure 71 How SSH Works

ES-2024A User’s Guide
124 Chapter 22 Access Control
Figure 70 SSH Communication Example
22.6 How SSH works
The following table summarizes how a secure connection is established between two remote
hosts.
Figure 71 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.