+----------+                                    +----------+         +----------+
     |          |                                    |          |         |          |
 eth1|          |eth0                                |          |     eth0|          |eth1
-----+ vyatta-A +-------------  INTERNET ------------+ Natruote +---------+ vyatta-B +-----
     |          |                                    |          |         |          |
     |          |                                    |          |         |          |
     +----+-----+                                    +----+-----+         +----+-----+

set system hostname router-A
set interfaces ethernet eth0 address 10.10.10.246/24
set interfaces ethernet eth1 address 192.168.10.246/24
set service nat rule 10 outbound-interface eth0
set service nat rule 10 source address 192.168.10.246/24
set service nat rule 10 type masquerade

set system hostname router-B
set interfaces ethernet eth0 address 10.10.20.75/24
set interfaces ethernet eth1 address 192.168.20.75/24
set service nat rule 10 outbound-interface eth0
set service nat rule 10 source address 192.168.20.75/24
set service nat rule 10 type masquerade

vyatta-A, vyatta-B ともに同じキーをコピーしておく。

$ generate openvpn key /config/auth/key.psk

set interfaces openvpn vtun0
set interfaces openvpn vtun0 mode site-to-site
set interfaces openvpn vtun0 local-address 172.16.100.246
set interfaces openvpn vtun0 remote-address 172.16.100.75
set interfaces openvpn vtun0 shared-secret-key-file /config/auth/key.psk

set interfaces openvpn vtun0
set interfaces openvpn vtun0 mode site-to-site
set interfaces openvpn vtun0 local-address 172.16.100.75
set interfaces openvpn vtun0 remote-address 172.16.100.246
set interfaces openvpn vtun0 remote-host 10.10.10.246
set interfaces openvpn vtun0 shared-secret-key-file /config/auth/key.psk

set protocols static route 192.168.20.0/24 next-hop 172.16.100.75

set protocols static route 192.168.10.0/24 next-hop 172.16.100.246