Set up vpn interface behind NAT
Hello there. I'm trying to set up a VPN tunnel with the interface behind NAT. Our main connection uses PPoE interface which is basically directly connected to FortiGate, it works fine. The backup connection though is behind ADSL modem, so it uses a private IP as a source, I made a port forwarding for 500 and 4500 from ADSL modem, but it's still down. I'd really appreciate any help, since i'm not a network engineer and i'm kinda new to the fortignet. Here are the diag commands:
diag vpn ike gateway
vd: root/0 name: BACKUP_Connection_btk version: 1 interface: wan1 5 addr: 192.168.100.2:500 -> 3*.**.***.***:500 created: 20s ago IKE SA: created 1/1 IPsec SA: created 0/0 id/spi: 22767 796fed2d927050f4/0000000000000000 direction: initiator status: connecting, state 3, started 20s ago
diag vpn tunnel list
name=BACKUP_Connection_btk ver=1 serial=5 192.168.100.2:0->3*.**.***.*** dst_mtu=0 bound_if=5 lgwy=static/1 tun=intf/0 mode=auto/1 encap=none/536 options[0218]=npu create_dev frag-rfc accept_traffic=0 proxyid_num=1 child_num=0 refcnt=9 ilast=23 olast=23 ad=/0 stat: rxp=0 txp=0 rxb=0 txb=0 dpd: mode=on-demand on=0 idle=20000ms retry=3 count=0 seqno=0 natt: mode=none draft=0 interval=0 remote_port=0 proxyid=MSQtoCER350_btk proto=0 sa=0 ref=1 serial=3 src: 0:10.100.0.0/255.255.0.0:0 dst: 0:10.31.0.0/255.255.0.0:0 0:10.0.19.0/255.255.255.0:0 0:10.1.19.0/255.255.255.0:0 0:10.198.0.0/255.255.0.0:0 0:10.55.1.0/255.255.255.0:0 0:10.31.18.0/255.255.255.0:0