ZyXEL Communications MGS3520 Series - 42.6 How SSH works

Chapter 42 Access Control
MGS3520 Series User’s Guide
363
Figure 231 SSH Communication Example
42.6 How SSH works
The following table summarizes how a secure connection is established between two remote hosts.
Figure 232 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.