VPN & Snort

[DaHai8]

Where does Snort sit in relation to pfSense's VPN services?
In other words, does Snort see the traffic before or after the VPN has processed/encrypted it?
Or to put it another way, is Snort useful on a VPN connection within pfSense, or does it only see the encrypted traffic and therefore can't examine/alert/block it?
Thanks.