Chapter 11 IPsec VPN for FortiOS 5.0 : FortiGate dialup-client configurations : Configure the FortiGate dialup client : Route-based VPN security policy
  
Route-based VPN security policy
Define an ACCEPT security policy to permit communications between hosts on the private network behind this FortiGate dialup client and the private network behind the FortiGate dialup server. Because communication cannot be initiated in the opposite direction, there is only one policy.
1. Go to Policy > Policy > Policy and select Create New.
2. Leave the Policy Type of Firewall and leave the Policy Subtype as Address.
3. Enter these settings in particular:
Incoming Interface
Select the interface that connects to the private network behind this FortiGate unit.
Source Address
Select All.
Outgoing Interface
Select the VPN tunnel (IPsec interface) created in Step 1.
Destination Address
Select All.
Action
Select ACCEPT.
Enable NAT
Disable