NAME
l2tp —
layer two tunneling protocol version
3
SYNOPSIS
pseudo-device l2tp
DESCRIPTION
Thel2tp interface implements version 3 of the Layer Two
Tunneling Protocol (L2TPv3). 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:
wm0 = 192.168.0.1/24 wm0 = 192.168.0.2/24
+------------+ +------------+
| NetBSD_A | | NetBSD_B |
|------------| |------------|
| [l2tp0] - - - - - - - - (tunnel) - - - - - - - - [l2tp0] |
| [wm0]------------- ... --------------[wm0] |
| | | |
+---[wm1]----+ +----[wm1]---+
| |
| |
+------------+ +------------+
| Host_X | | Host_Y |
+------------+ +------------+
Configuration example without cookies
On NetBSD_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_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_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_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.