Hey Anne,
I don' t believe you' re going to be able to use LDAP/AD with IPSEC vpn. In 4.x there was an option to specify an authusrgrp via CLI where you could choose a remote LDAP server but I don' t see it in 5.
Here' s some info from the Authentication handbook guide for IPSEC:
" Authenticating IPsec VPN users
An IPsec VPN can be configured to accept connections from multiple dynamically addressed peers. You would do this to enable employees to connect to the corporate network while traveling or from home. On a FortiGate unit, you create this configuration by setting the Remote Gateway to Dialup User.
It is possible to have an IPsec VPN in which re
mote peer devices authenticate using a common
preshared key or a certificate, but there is no attempt to identify the user at the remote peer. To add user authentication, you can do one of the following:
• require a unique preshared key for each peer
• require a unique peer ID for each peer
• require a unique peer certificate for each peer
• require additional user authentication (XAuth)
The peer ID is a text string configured on the peer device. On a FortiGate peer or FortiClient Endpoint Security peer, the peer ID provided to the remote peer is called the Local ID. "