Command Section
if_ipsec(4)            FreeBSD Kernel Interfaces Manual            if_ipsec(4)

     if_ipsec - IPsec virtual tunneling interface

     The if_ipsec network interface is a part of the FreeBSD IPsec
     implementation.  To compile it into the kernel, place this line in the
     kernel configuration file:

           options IPSEC

     It can also be loaded as part of the ipsec kernel module if the kernel
     was compiled with

           options IPSEC_SUPPORT

     The if_ipsec network interface is targeted for creating route-based VPNs.
     It can tunnel IPv4 and IPv6 traffic over either IPv4 or IPv6 and secure
     it with ESP.

     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

     The example below shows manual configuration of an IPsec tunnel between
     two FreeBSD hosts.  Host A has the IP address, and host B has
     the IP address

     On host A:

           ifconfig ipsec0 create reqid 100
           ifconfig ipsec0 inet tunnel
           ifconfig ipsec0 inet
           setkey -c
           add esp 10000 -m tunnel -u 100 -E rijndael-cbc "VerySecureKey!!1";
           add esp 10001 -m tunnel -u 100 -E rijndael-cbc "VerySecureKey!!2";

     On host B:

           ifconfig ipsec0 create reqid 200
           ifconfig ipsec0 inet tunnel
           ifconfig ipsec0 inet
           setkey -c
           add esp 10000 -m tunnel -u 200 -E rijndael-cbc "VerySecureKey!!1";
           add esp 10001 -m tunnel -u 200 -E rijndael-cbc "VerySecureKey!!2";

     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.

     gif(4), gre(4), ipsec(4), ifconfig(8), setkey(8)

     Andrey V. Elsukov <[email protected]>

FreeBSD 11.1-RELEASE-p4        February 6, 2017        FreeBSD 11.1-RELEASE-p4
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