IPSEC Policy Mode Source Nat Problems

[mtcook01]

Hello, I have a IPSEC tunnel which is showing UP but I cannot ping or access the needed website though the tunnel.  I am connecting to a City VPN which uses a Checkpoint Firewall.  They require me to Source Nat to protect them from subnet overlap.  I have read a million manuals and spent days in forums, blogs and various tutorials to no avail.  It appears the traffic is moving into the tunnel but I get no response.

I have configured source Nat from my public interface address.  - I have other public IP's if they must be used.  The interface IP seemed easiest.  Also I am using Policy mode.  I know route mode is better, but I cannot find any documentation on source NAT for that vpn type.  My config is below.  Any help might just keep the two hairs I have left in place.

** Note ** I would love to convert this into a route based VPN, but have no idea how to do Source Nat.  VIPs don't make sense when the traffic is initiated from the Wan interface.  I must be missing something.

All IPs have been cleansed.

Fortigate 100E  Firmware v5.6.2 build1486 (GA

Remote Interface Gateway 178.19.115.184 Remote Subnet 178.19.196.128 255.255.255.128 Local Gateway 88.235.171.66 -This is my WAN Address- Local Subnet 192.168.200.0 255.255.255.0 - Internal Address ** Goal is to have all traffic from Local Subnet NAT to WAN Interface **   config firewall address  edit "VPN-Metro_Local"         set color 4         set allow-routing enable         set subnet 192.168.200.0 255.255.255.0     next     edit "VPN-Metro_Remote"         set color 4         set allow-routing enable         set subnet 178.19.196.128 255.255.255.128  next       config vpn ipsec phase1     edit "Metro_Phase1"         set interface "wan1"         set keylife 28800         set peertype any         set proposal aes256-sha1         set comments "Metro VPN Phase 1"         set dhgrp 2         set remote-gw 178.19.15.84         set psksecret ENC     next end config vpn ipsec phase2     edit "Metro_Phase2"         set phase1name "Metro_Phase1"         set use-natip disable         set proposal aes256-sha1         set pfs disable         set auto-negotiate enable         set comments "Metro VPN Phase 2"         set src-addr-type ip         set src-start-ip 88.235.171.66         set dst-subnet 178.19.196.128 255.255.255.128     next end config firewall policy     edit 15         set name "MetroRMS_Policy_200Net"         set srcintf "lan"         set dstintf "wan1"         set srcaddr "VPN-Metro_Local"         set dstaddr "VPN-Metro_Remote"         set action ipsec         set schedule "always"         set service "ALL"         set logtraffic all         set inbound enable         set natoutbound enable         set vpntunnel "Metro_Phase1"     next end id=20085 trace_id=777 func=print_pkt_detail line=5363 msg="vd-root received a packet(proto=1, 192.168.200.198:1->178.19.196.145:2048) from lan. type=8, code=0, id=1, seq=300." id=20085 trace_id=777 func=resolve_ip_tuple_fast line=5438 msg="Find an existing session, id-00068aef, original direction" id=20085 trace_id=777 func=npu_handle_session44 line=1079 msg="Trying to offloading session from lan to wan1, skb.npu_flag=00000400 ses.state=00050214 ses.npu_state=0x01000000" id=20085 trace_id=777 func=__ip_session_run_tuple line=3164 msg="SNAT 192.168.200.198->88.235.171.66:62464" id=20085 trace_id=777 func=ipsec_tunnel_output4 line=1211 msg="enter IPsec tunnel-MetroRMS_Phase1" id=20085 trace_id=777 func=esp_output4 line=891 msg="IPsec encrypt/auth" id=20085 trace_id=777 func=ipsec_output_finish line=525 msg="send to 88.235.171.65 via intf-wan1"

[EMES]

Try using another public address. If you use the same ip.to form the tunnel and the same ip to nat. The return traffic may go back over the Internet instead of the tunnel.

[mtcook01]

I thought about that too.  I will try that. I think if I use another public IP I can actually do this in route mode using a VIP.  

Thanks for taking the time to respond. I will let you know how it works out.

[EMES]

Change to route mode and set the phase 2 selectors properly. The nat will happen using an IP pool outbound. You set that in the security policy from inside to the vpn tunnel interface.