System information

Chapter 8 Customizing Services 125
A secure shared secret is generated automatically when you set up your server. The
shared secret isn’t used to authenticate client computer users for a VPN connection.
Instead it allows the server to trust client computers that have the shared secret, and it
allows client computers to trust the server that has the secret.
Both server and client computers must have the shared secret. A computer with
Mac OS X version 10.5 Leopard can automatically get the shared secret and be set up
to make connections to the server’s VPN service. See “Setting Up Leopard Users’ Macs
Automatically” on page 79.
Other Mac and Windows computers can be configured in different ways to connect to
the VPN service. See “Setting Up a Mac User’s VPN Connection” on page 87 and
“Setting Up a User’s VPN Connection Manually” on page 89.
Changing the VPN Shared Secret
You can use Server Preferences to change the shared secret that the server and a client
computer use for authentication when making a VPN connection. Periodically
changing the shared secret improves VPN security, but is inconvenient because users
must also change the shared secret on computers they use for VPN connections.
To change the VPN shared secret:
1 In the VPN pane of Server Preferences, click Edit.
2 Select “Show shared secret” so you can read the secret, enter a new secret, and
click OK.
The shared secret should be at least 8, but preferably 12 or more characters including
letters, digits, and symbols, but without spaces. Initially the shared secret is 32 random
characters.