Site-to-site IPv6 over IPv4 VPN example
In this example, IPv6-addressed private networks communicate securely over IPv4 public infrastructure.
Example IPv6-over-IPv4 VPN topology
Configure FortiGate A interfaces
Port 2 connects to the IPv4 public network and port 3 connects to the IPv6 LAN.
config system interface
edit port2
set 10.0.0.1/24
next
edit port3
config ipv6
set ip6-address fec0::0001:209:0fff:fe83:25f3/64
end
Configure FortiGate A IPsec settings
The Phase 1 configuration uses IPv4 addressing.
config vpn ipsec phase1-interface
edit toB
set interface port2
set remote-gw 10.0.1.1
set dpd enable
set psksecret maryhadalittlelamb
set proposal 3des-md5 3des-sha1
end
The Phase 2 configuration uses IPv6 selectors. By default, Phase 2 selectors are set to accept all subnet addresses for source and destination. The default setting for src‑addr-type and dst-addr-type is subnet. The IPv6 equivalent is subnet6. The default subnet addresses are 0.0.0.0/0 for IPv4, ::/0
for IPv6.
config vpn ipsec phase2-interface
edit toB2
set phase1name toB
set proposal 3des-md5 3des-sha1
set pfs enable
set replay enable
set src-addr-type subnet6
set dst-addr-type subnet6
end
Configure FortiGate A security policies
IPv6 security policies are required to allow traffic between port3 and the IPsec interface toB in each direction. Define the address all6 using the firewall address6
command as ::/0
.
config firewall policy6
edit 1
set srcintf port3
set dstintf toB
set srcaddr all6
set dstaddr all6
set action accept
set service ANY
set schedule always
next
edit 2
set srcintf toB
set dstintf port3
set srcaddr all6
set dstaddr all6
set action accept
set service ANY
set schedule always
end
Configure FortiGate A routing
This simple example requires just two static routes. Traffic to the protected network behind FortiGate B is routed via the virtual IPsec interface toB using an IPv6 static route. A default route sends all IPv4 traffic, including the IPv4 IPsec packets, out on port2.
config router static6
edit 1
set device toB
set dst fec0:0000:0000:0004::/64
end
config router static
edit 1
set device port2
set dst 0.0.0.0/0
set gateway 10.0.0.254
end
Configure FortiGate B
The configuration of FortiGate B is very similar to that of FortiGate A. A virtual IPsec interface toA is configured on port2 and its remote gateway is the IPv4 public IP address of FortiGate A. The IPsec Phase 2 configuration has IPv6 selectors.
IPv6 security policies enable traffic to pass between the private network and the IPsec interface. An IPv6 static route ensures traffic for the private network behind FortiGate A goes through the VPN and an IPv4 static route ensures that all IPv4 packets are routed to the public network.
config system interface
edit port2
set 10.0.1.1/24
next
edit port3
config ipv6
set ip6-address fec0::0004:209:0fff:fe83:2569/64
end
config vpn ipsec phase1-interface
edit toA
set interface port2
set remote-gw 10.0.0.1
set dpd enable
set psksecret maryhadalittlelamb
set proposal 3des-md5 3des-sha1
end
config vpn ipsec phase2-interface
edit toA2
set phase1name toA
set proposal 3des-md5 3des-sha1
set pfs enable
set replay enable
set src-addr-type subnet6
set dst-addr-type subnet6
end
config firewall policy6
edit 1
set srcintf port3
set dstintf toA
set srcaddr all6
set dstaddr all6
set action accept
set service ANY
set schedule always
next
edit 2
set srcintf toA
set dstintf port3
set srcaddr all6
set dstaddr all6
set action accept
set service ANY
set schedule always
end
config router static6
edit 1
set device toA
set dst fec0:0000:0000:0000::/64
end
config router static
edit 1
set device port2
set gateway 10.0.1.254
end