ZyXEL Communications 110, 1100, 310 manual 473

Chapter 37 System

Figure 324 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 325 How SSH v1 Works Example

1Host 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.

2Encryption Method

Once the identification is verified, both the client and server must agree on the type of encryption method to use.

3Authentication 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.

	473
ZyWALL 110/310/1100 Series User’s Guide