Manual Pages  — if_ipsec

if_ipsec interfaces are dynamically created and destroyed with the ifconfig(8) create and destroy subcommands. The administrator must configure IPsec tunnel endpoint addresses. These addresses will be used for the outer IP header of ESP packets. The administrator can also configure the protocol and addresses for the inner IP header with ifconfig(8), and modify the routing table to route the packets through the if_ipsec interface.

When the if_ipsec interface is configured, it automatically creates special security policies. These policies can be used to acquire security associations from the IKE daemon, which are needed for establishing an IPsec tunnel. It is also possible to create needed security associations manually with the setkey(8) utility.

Each if_ipsec interface has an additional numeric configuration option reqid id. This id is used to distinguish traffic and security policies between several if_ipsec interfaces. The reqid can be specified on interface creation and changed later. If not specified, it is automatically assigned. Note that changing reqid will lead to generation of new security policies, and this may require creating new security associations.

ifconfig ipsec0 create reqid 100
ifconfig ipsec0 inet tunnel 192.168.0.3 192.168.0.5
ifconfig ipsec0 inet 172.16.0.3/16 172.16.0.5
setkey -c
add 192.168.0.3 192.168.0.5 esp 10000 -m tunnel -u 100 -E rijndael-cbc "VerySecureKey!!1";
add 192.168.0.5 192.168.0.3 esp 10001 -m tunnel -u 100 -E rijndael-cbc "VerySecureKey!!2";
^D

ifconfig ipsec0 create reqid 200
ifconfig ipsec0 inet tunnel 192.168.0.5 192.168.0.3
ifconfig ipsec0 inet 172.16.0.5/16 172.16.0.3
setkey -c
add 192.168.0.3 192.168.0.5 esp 10000 -m tunnel -u 200 -E rijndael-cbc "VerySecureKey!!1";
add 192.168.0.5 192.168.0.3 esp 10001 -m tunnel -u 200 -E rijndael-cbc "VerySecureKey!!2";
^D

Note the value 100 on host A and value 200 on host B are used as reqid. The same value must be used as identifier of the policy entry in the setkey(8) command.