Chapter 10 Install and System Administration for FortiOS 5.0 : PPTP and L2TP : Adding the security policy : Logging L2TP VPN events
  
Logging L2TP VPN events
You can configure the FortiGate unit to log VPN events. For L2TP VPNs, connection events and tunnel status (up/down) are logged.
To log VPN events - web-based manager
1. Go to Log & Report > Log Config > Log Settings.
2. Enable the storage of log messages to one or more locations.
3. Select Enable, and then select VPN activity event.
4. Select Apply.
To log VPN events - CLI
config log memory setting
set diskfull overright
set status enable
end
config log eventfilter
set ppp
end
See Also
Configuring a Linux client
Monitoring L2TP sessions
Testing L2TP VPN connections
Adding the security policy
PPTP and L2TP