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> Chapter 14 - IPsec VPN > IPv6 IPsec VPNs > Site-to-site IPv6 over IPv4 VPN example

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