Cisco VPN pass through not working when behind pfSense
From pfSense Documentation
If trouble is encountered when attempting a connection from an internal Cisco VPN client to an external host, (e.g. a workstation with the Cisco client is trying to get out through pfSense to connect to a "foreign" site), then try the following.
- In the Cisco VPN client software, Modify the connection and turn off transparent tunneling completely in the Transport tab.
- In the pfSense, under Firewall > NAT on the Outbound tab, enable Manual Outbound NAT. Remove any NAT rules that perform static port NAT on udp/500.