Chapter 22 WAN Optimization, Web Cache, Explicit Proxy, and WCCP for FortiOS 5.0 : Configuring WAN optimization : Manual (peer-to-peer) and active-passive WAN optimization : Active-passive configurations : Server-side tunnel policy
  
Server-side tunnel policy
The server-side requires a policy that allows WAN optimization tunnel connections by including the wanopt tunnel interface as the Incoming Interface. From the CLI the policy could look like the following:
configure firewall policy
edit 3
set srcintf "wanopt"
set dstintf "internal"
set srcaddr "all"
set dstaddr "server-subnet"
set action accept
set schedule "always"
set service "ANY"
next
end