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L2TP(4)                      Device Drivers Manual                     L2TP(4)

NAME
     l2tp - layer two tunneling protocol version 3

SYNOPSIS
     pseudo-device l2tp

DESCRIPTION
     The l2tp interface is a version 3 of the Layer Two Tunneling Protocol
     (L2TPv3) pseudo device.  It can tunnel layer 2 protocol traffic over IPv4
     or IPv6, as specified in RFC3931.

     The L2TPv3 protocol is comprised of two types of messages, control
     messages and data messages.  Control messages are used in the
     establishment, maintenace, and clearing of control connections and
     sessions.  The l2tp interface can send control messages and data
     messages; furthermore the management of control messages is entrusted to
     userland daemon.  Without a management daemon, the l2tp interface can
     send data messages using the ifconfig(8) tunnel and session subcommands,
     or the SIOCSIFPHYADDR and SIOCSL2TPSESSION ioctls.  Additionally, it can
     use cookies specified in RFC3931 by using the ifconfig(8) cookie
     subcommand, or the SIOCSL2TPCOOKIE ioctl.

   Packet format
     Layer 2 frames are prepended with a L2TPv3 header as described by RFC
     3931.  The resulting L2TPv3 packets will be encapsulated in an outer
     packet, which may be either an IPv4 or IPv6 packet, with IP protocol
     number 115.

EXAMPLES
     Configuration example:

     Host X--NetBSD A  ----------------tunnel---------- NetBSD B------Host E
                \                                          |
                 \                                        /
                  +-----Router B--------Router C---------+
     configuration example without cookies,

     On NetBSD system A

     # ifconfig wm0 inet 192.168.0.1/24
     # ifconfig l2tp0 create
     # ifconfig l2tp0 tunnel 192.168.0.1 192.168.0.2
     # ifconfig l2tp0 session 1234 4321
     # ifconfig bridge0 create
     # brconfig bridge0 add wm1
     # brconfig bridge0 add l2tp0
     # ifconfig l2tp0 up
     # ifconfig wm1 up
     # ifconfig bridge0 up

     On NetBSD system B

     # ifconfig wm0 inet 192.168.0.2/24
     # ifconfig l2tp0 create
     # ifconfig l2tp0 tunnel 192.168.0.2 192.168.0.1
     # ifconfig l2tp0 session 4321 1234
     # ifconfig bridge0 create
     # brconfig bridge0 add wm1
     # brconfig bridge0 add l2tp0
     # ifconfig l2tp0 up
     # ifconfig wm1 up
     # ifconfig bridge0 up

     configuration example with cookies,

     On NetBSD system A

     # ifconfig wm0 inet 192.168.0.1/24
     # ifconfig l2tp0 create
     # ifconfig l2tp0 tunnel 192.168.0.1 192.168.0.2
     # ifconfig l2tp0 session 1234 4321
     # ifconfig l2tp0 cookie 4 12345 4 54321
     # ifconfig bridge0 create
     # brconfig bridge0 add wm1
     # brconfig bridge0 add l2tp0
     # ifconfig l2tp0 up
     # ifconfig wm1 up
     # ifconfig bridge0 up

     On NetBSD system B

     # ifconfig wm0 inet 192.168.0.2/24
     # ifconfig l2tp0 create
     # ifconfig l2tp0 tunnel 192.168.0.2 192.168.0.1
     # ifconfig l2tp0 session 4321 1234
     # ifconfig l2tp0 cookie 4 54321 4 12345
     # ifconfig bridge0 create
     # brconfig bridge0 add wm1
     # brconfig bridge0 add l2tp0
     # ifconfig l2tp0 up
     # ifconfig wm1 up
     # ifconfig bridge0 up

SEE ALSO
     inet(4), inet6(4), ifconfig(8)

     J. Lau, Ed., M. Townsley, Ed., and I. Goyret, Ed., "Layer Two Tunneling
     Protocol - Version 3 (L2TPv3)", RFC 3931,
     ftp://ftp.ietf.org/rfc/rfc3931.txt, March 2005.

HISTORY
     The l2tp device first appeared in NetBSD 8.0.

BUGS
     Currently, the l2tp interface supports Ethernet frames over IPv4 or IPv6
     only.

NetBSD 8.0                     January 19, 2017                     NetBSD 8.0