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docs: networking: convert l2tp.txt to ReST

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- add SPDX header;
- add a document title;
- mark tables as such;
- adjust identation, whitespaces and blank lines;
- add to networking/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Mauro Carvalho Chehab
2020-04-30 18:03:56 +02:00
committed by David S. Miller
parent 9f04960660
commit 10ebb22137
2 changed files with 80 additions and 66 deletions
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1
Documentation/networking/index.rst
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@@ -74,6 +74,7 @@ Contents:
ipvlan ipvlan
ipvs-sysctl ipvs-sysctl
kcm kcm
l2tp
.. only:: subproject and html .. only:: subproject and html

145
Documentation/networking/l2tp.txt → Documentation/networking/l2tp.rst
View File

@@ -1,3 +1,9 @@
.. SPDX-License-Identifier: GPL-2.0
====
L2TP
====
This document describes how to use the kernel's L2TP drivers to This document describes how to use the kernel's L2TP drivers to
provide L2TP functionality. L2TP is a protocol that tunnels one or provide L2TP functionality. L2TP is a protocol that tunnels one or
more sessions over an IP tunnel. It is commonly used for VPNs more sessions over an IP tunnel. It is commonly used for VPNs
@@ -121,14 +127,16 @@ Userspace may control behavior of the tunnel or session using
setsockopt and ioctl on the PPPoX socket. The following socket setsockopt and ioctl on the PPPoX socket. The following socket
options are supported:- options are supported:-
DEBUG - bitmask of debug message categories. See below. ========= ===========================================================
SENDSEQ - 0 => don't send packets with sequence numbers DEBUG bitmask of debug message categories. See below.
1 => send packets with sequence numbers SENDSEQ - 0 => don't send packets with sequence numbers
RECVSEQ - 0 => receive packet sequence numbers are optional - 1 => send packets with sequence numbers
1 => drop receive packets without sequence numbers RECVSEQ - 0 => receive packet sequence numbers are optional
LNSMODE - 0 => act as LAC. - 1 => drop receive packets without sequence numbers
1 => act as LNS. LNSMODE - 0 => act as LAC.
REORDERTO - reorder timeout (in millisecs). If 0, don't try to reorder. - 1 => act as LNS.
REORDERTO reorder timeout (in millisecs). If 0, don't try to reorder.
========= ===========================================================
Only the DEBUG option is supported by the special tunnel management Only the DEBUG option is supported by the special tunnel management
PPPoX socket. PPPoX socket.
@@ -177,20 +185,22 @@ setsockopt on the PPPoX socket to set a debug mask.
The following debug mask bits are available: The following debug mask bits are available:
================ ==============================
L2TP_MSG_DEBUG verbose debug (if compiled in) L2TP_MSG_DEBUG verbose debug (if compiled in)
L2TP_MSG_CONTROL userspace - kernel interface L2TP_MSG_CONTROL userspace - kernel interface
L2TP_MSG_SEQ sequence numbers handling L2TP_MSG_SEQ sequence numbers handling
L2TP_MSG_DATA data packets L2TP_MSG_DATA data packets
================ ==============================
If enabled, files under a l2tp debugfs directory can be used to dump If enabled, files under a l2tp debugfs directory can be used to dump
kernel state about L2TP tunnels and sessions. To access it, the kernel state about L2TP tunnels and sessions. To access it, the
debugfs filesystem must first be mounted. debugfs filesystem must first be mounted::
# mount -t debugfs debugfs /debug # mount -t debugfs debugfs /debug
Files under the l2tp directory can then be accessed. Files under the l2tp directory can then be accessed::
# cat /debug/l2tp/tunnels # cat /debug/l2tp/tunnels
The debugfs files should not be used by applications to obtain L2TP The debugfs files should not be used by applications to obtain L2TP
state information because the file format is subject to change. It is state information because the file format is subject to change. It is
@@ -211,14 +221,14 @@ iproute2's ip utility to support this.
To create an L2TPv3 ethernet pseudowire between local host 192.168.1.1 To create an L2TPv3 ethernet pseudowire between local host 192.168.1.1
and peer 192.168.1.2, using IP addresses 10.5.1.1 and 10.5.1.2 for the and peer 192.168.1.2, using IP addresses 10.5.1.1 and 10.5.1.2 for the
tunnel endpoints:- tunnel endpoints::
# ip l2tp add tunnel tunnel_id 1 peer_tunnel_id 1 udp_sport 5000 \ # ip l2tp add tunnel tunnel_id 1 peer_tunnel_id 1 udp_sport 5000 \
udp_dport 5000 encap udp local 192.168.1.1 remote 192.168.1.2 udp_dport 5000 encap udp local 192.168.1.1 remote 192.168.1.2
# ip l2tp add session tunnel_id 1 session_id 1 peer_session_id 1 # ip l2tp add session tunnel_id 1 session_id 1 peer_session_id 1
# ip -s -d show dev l2tpeth0 # ip -s -d show dev l2tpeth0
# ip addr add 10.5.1.2/32 peer 10.5.1.1/32 dev l2tpeth0 # ip addr add 10.5.1.2/32 peer 10.5.1.1/32 dev l2tpeth0
# ip li set dev l2tpeth0 up # ip li set dev l2tpeth0 up
Choose IP addresses to be the address of a local IP interface and that Choose IP addresses to be the address of a local IP interface and that
of the remote system. The IP addresses of the l2tpeth0 interface can be of the remote system. The IP addresses of the l2tpeth0 interface can be
@@ -228,75 +238,78 @@ Repeat the above at the peer, with ports, tunnel/session ids and IP
addresses reversed. The tunnel and session IDs can be any non-zero addresses reversed. The tunnel and session IDs can be any non-zero
32-bit number, but the values must be reversed at the peer. 32-bit number, but the values must be reversed at the peer.
======================== ===================
Host 1 Host2 Host 1 Host2
======================== ===================
udp_sport=5000 udp_sport=5001 udp_sport=5000 udp_sport=5001
udp_dport=5001 udp_dport=5000 udp_dport=5001 udp_dport=5000
tunnel_id=42 tunnel_id=45 tunnel_id=42 tunnel_id=45
peer_tunnel_id=45 peer_tunnel_id=42 peer_tunnel_id=45 peer_tunnel_id=42
session_id=128 session_id=5196755 session_id=128 session_id=5196755
peer_session_id=5196755 peer_session_id=128 peer_session_id=5196755 peer_session_id=128
======================== ===================
When done at both ends of the tunnel, it should be possible to send When done at both ends of the tunnel, it should be possible to send
data over the network. e.g. data over the network. e.g.::
# ping 10.5.1.1 # ping 10.5.1.1
Sample Userspace Code Sample Userspace Code
===================== =====================
1. Create tunnel management PPPoX socket 1. Create tunnel management PPPoX socket::
kernel_fd = socket(AF_PPPOX, SOCK_DGRAM, PX_PROTO_OL2TP); kernel_fd = socket(AF_PPPOX, SOCK_DGRAM, PX_PROTO_OL2TP);
if (kernel_fd >= 0) { if (kernel_fd >= 0) {
struct sockaddr_pppol2tp sax; struct sockaddr_pppol2tp sax;
struct sockaddr_in const *peer_addr; struct sockaddr_in const *peer_addr;
peer_addr = l2tp_tunnel_get_peer_addr(tunnel); peer_addr = l2tp_tunnel_get_peer_addr(tunnel);
memset(&sax, 0, sizeof(sax)); memset(&sax, 0, sizeof(sax));
sax.sa_family = AF_PPPOX; sax.sa_family = AF_PPPOX;
sax.sa_protocol = PX_PROTO_OL2TP; sax.sa_protocol = PX_PROTO_OL2TP;
sax.pppol2tp.fd = udp_fd; /* fd of tunnel UDP socket */ sax.pppol2tp.fd = udp_fd; /* fd of tunnel UDP socket */
sax.pppol2tp.addr.sin_addr.s_addr = peer_addr->sin_addr.s_addr; sax.pppol2tp.addr.sin_addr.s_addr = peer_addr->sin_addr.s_addr;
sax.pppol2tp.addr.sin_port = peer_addr->sin_port; sax.pppol2tp.addr.sin_port = peer_addr->sin_port;
sax.pppol2tp.addr.sin_family = AF_INET; sax.pppol2tp.addr.sin_family = AF_INET;
sax.pppol2tp.s_tunnel = tunnel_id; sax.pppol2tp.s_tunnel = tunnel_id;
sax.pppol2tp.s_session = 0; /* special case: mgmt socket */ sax.pppol2tp.s_session = 0; /* special case: mgmt socket */
sax.pppol2tp.d_tunnel = 0; sax.pppol2tp.d_tunnel = 0;
sax.pppol2tp.d_session = 0; /* special case: mgmt socket */ sax.pppol2tp.d_session = 0; /* special case: mgmt socket */
if(connect(kernel_fd, (struct sockaddr *)&sax, sizeof(sax) ) < 0 ) { if(connect(kernel_fd, (struct sockaddr *)&sax, sizeof(sax) ) < 0 ) {
perror("connect failed"); perror("connect failed");
result = -errno; result = -errno;
goto err; goto err;
} }
} }
2. Create session PPPoX data socket 2. Create session PPPoX data socket::
struct sockaddr_pppol2tp sax; struct sockaddr_pppol2tp sax;
int fd; int fd;
/* Note, the target socket must be bound already, else it will not be ready */ /* Note, the target socket must be bound already, else it will not be ready */
sax.sa_family = AF_PPPOX; sax.sa_family = AF_PPPOX;
sax.sa_protocol = PX_PROTO_OL2TP; sax.sa_protocol = PX_PROTO_OL2TP;
sax.pppol2tp.fd = tunnel_fd; sax.pppol2tp.fd = tunnel_fd;
sax.pppol2tp.addr.sin_addr.s_addr = addr->sin_addr.s_addr; sax.pppol2tp.addr.sin_addr.s_addr = addr->sin_addr.s_addr;
sax.pppol2tp.addr.sin_port = addr->sin_port; sax.pppol2tp.addr.sin_port = addr->sin_port;
sax.pppol2tp.addr.sin_family = AF_INET; sax.pppol2tp.addr.sin_family = AF_INET;
sax.pppol2tp.s_tunnel = tunnel_id; sax.pppol2tp.s_tunnel = tunnel_id;
sax.pppol2tp.s_session = session_id; sax.pppol2tp.s_session = session_id;
sax.pppol2tp.d_tunnel = peer_tunnel_id; sax.pppol2tp.d_tunnel = peer_tunnel_id;
sax.pppol2tp.d_session = peer_session_id; sax.pppol2tp.d_session = peer_session_id;
/* session_fd is the fd of the session's PPPoL2TP socket. /* session_fd is the fd of the session's PPPoL2TP socket.
* tunnel_fd is the fd of the tunnel UDP socket. * tunnel_fd is the fd of the tunnel UDP socket.
*/ */
fd = connect(session_fd, (struct sockaddr *)&sax, sizeof(sax)); fd = connect(session_fd, (struct sockaddr *)&sax, sizeof(sax));
if (fd < 0 ) { if (fd < 0 ) {
return -errno; return -errno;
} }
return 0; return 0;
Internal Implementation Internal Implementation
======================= =======================