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Message-Id: <157b3aa863c15a4b8feeeb0cdd5475c2596c5dde.1588261997.git.mchehab+huawei@kernel.org>
Date: Thu, 30 Apr 2020 18:03:56 +0200
From: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
To: Linux Doc Mailing List <linux-doc@...r.kernel.org>
Cc: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
linux-kernel@...r.kernel.org, Jonathan Corbet <corbet@....net>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org
Subject: [PATCH 01/37] docs: networking: convert l2tp.txt to ReST
- 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@...nel.org>
---
Documentation/networking/index.rst | 1 +
.../networking/{l2tp.txt => l2tp.rst} | 145 ++++++++++--------
2 files changed, 80 insertions(+), 66 deletions(-)
rename Documentation/networking/{l2tp.txt => l2tp.rst} (79%)
diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst
index e1ff08b94d90..0c5d7a037983 100644
--- a/Documentation/networking/index.rst
+++ b/Documentation/networking/index.rst
@@ -74,6 +74,7 @@ Contents:
ipvlan
ipvs-sysctl
kcm
+ l2tp
.. only:: subproject and html
diff --git a/Documentation/networking/l2tp.txt b/Documentation/networking/l2tp.rst
similarity index 79%
rename from Documentation/networking/l2tp.txt
rename to Documentation/networking/l2tp.rst
index 9bc271cdc9a8..a48238a2ec09 100644
--- a/Documentation/networking/l2tp.txt
+++ b/Documentation/networking/l2tp.rst
@@ -1,3 +1,9 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====
+L2TP
+====
+
This document describes how to use the kernel's L2TP drivers to
provide L2TP functionality. L2TP is a protocol that tunnels one or
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
options are supported:-
-DEBUG - bitmask of debug message categories. See below.
-SENDSEQ - 0 => don't send packets with sequence numbers
- 1 => send packets with sequence numbers
-RECVSEQ - 0 => receive packet sequence numbers are optional
- 1 => drop receive packets without sequence numbers
-LNSMODE - 0 => act as LAC.
- 1 => act as LNS.
-REORDERTO - reorder timeout (in millisecs). If 0, don't try to reorder.
+========= ===========================================================
+DEBUG bitmask of debug message categories. See below.
+SENDSEQ - 0 => don't send packets with sequence numbers
+ - 1 => send packets with sequence numbers
+RECVSEQ - 0 => receive packet sequence numbers are optional
+ - 1 => drop receive packets without sequence numbers
+LNSMODE - 0 => act as LAC.
+ - 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
PPPoX socket.
@@ -177,20 +185,22 @@ setsockopt on the PPPoX socket to set a debug mask.
The following debug mask bits are available:
+================ ==============================
L2TP_MSG_DEBUG verbose debug (if compiled in)
L2TP_MSG_CONTROL userspace - kernel interface
L2TP_MSG_SEQ sequence numbers handling
L2TP_MSG_DATA data packets
+================ ==============================
If enabled, files under a l2tp debugfs directory can be used to dump
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
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
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 \
- 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 -s -d show 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 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
+ # ip l2tp add session tunnel_id 1 session_id 1 peer_session_id 1
+ # ip -s -d show dev l2tpeth0
+ # ip addr add 10.5.1.2/32 peer 10.5.1.1/32 dev l2tpeth0
+ # ip li set dev l2tpeth0 up
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
@@ -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
32-bit number, but the values must be reversed at the peer.
+======================== ===================
Host 1 Host2
+======================== ===================
udp_sport=5000 udp_sport=5001
udp_dport=5001 udp_dport=5000
tunnel_id=42 tunnel_id=45
peer_tunnel_id=45 peer_tunnel_id=42
session_id=128 session_id=5196755
peer_session_id=5196755 peer_session_id=128
+======================== ===================
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
=====================
-1. Create tunnel management PPPoX socket
+1. Create tunnel management PPPoX socket::
- kernel_fd = socket(AF_PPPOX, SOCK_DGRAM, PX_PROTO_OL2TP);
- if (kernel_fd >= 0) {
- struct sockaddr_pppol2tp sax;
- struct sockaddr_in const *peer_addr;
+ kernel_fd = socket(AF_PPPOX, SOCK_DGRAM, PX_PROTO_OL2TP);
+ if (kernel_fd >= 0) {
+ struct sockaddr_pppol2tp sax;
+ struct sockaddr_in const *peer_addr;
- peer_addr = l2tp_tunnel_get_peer_addr(tunnel);
- memset(&sax, 0, sizeof(sax));
- sax.sa_family = AF_PPPOX;
- sax.sa_protocol = PX_PROTO_OL2TP;
- 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_port = peer_addr->sin_port;
- sax.pppol2tp.addr.sin_family = AF_INET;
- sax.pppol2tp.s_tunnel = tunnel_id;
- sax.pppol2tp.s_session = 0; /* special case: mgmt socket */
- sax.pppol2tp.d_tunnel = 0;
- sax.pppol2tp.d_session = 0; /* special case: mgmt socket */
+ peer_addr = l2tp_tunnel_get_peer_addr(tunnel);
+ memset(&sax, 0, sizeof(sax));
+ sax.sa_family = AF_PPPOX;
+ sax.sa_protocol = PX_PROTO_OL2TP;
+ 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_port = peer_addr->sin_port;
+ sax.pppol2tp.addr.sin_family = AF_INET;
+ sax.pppol2tp.s_tunnel = tunnel_id;
+ sax.pppol2tp.s_session = 0; /* special case: mgmt socket */
+ sax.pppol2tp.d_tunnel = 0;
+ sax.pppol2tp.d_session = 0; /* special case: mgmt socket */
- if(connect(kernel_fd, (struct sockaddr *)&sax, sizeof(sax) ) < 0 ) {
- perror("connect failed");
- result = -errno;
- goto err;
- }
- }
+ if(connect(kernel_fd, (struct sockaddr *)&sax, sizeof(sax) ) < 0 ) {
+ perror("connect failed");
+ result = -errno;
+ goto err;
+ }
+ }
-2. Create session PPPoX data socket
+2. Create session PPPoX data socket::
- struct sockaddr_pppol2tp sax;
- int fd;
+ struct sockaddr_pppol2tp sax;
+ int fd;
- /* Note, the target socket must be bound already, else it will not be ready */
- sax.sa_family = AF_PPPOX;
- sax.sa_protocol = PX_PROTO_OL2TP;
- sax.pppol2tp.fd = tunnel_fd;
- sax.pppol2tp.addr.sin_addr.s_addr = addr->sin_addr.s_addr;
- sax.pppol2tp.addr.sin_port = addr->sin_port;
- sax.pppol2tp.addr.sin_family = AF_INET;
- sax.pppol2tp.s_tunnel = tunnel_id;
- sax.pppol2tp.s_session = session_id;
- sax.pppol2tp.d_tunnel = peer_tunnel_id;
- sax.pppol2tp.d_session = peer_session_id;
+ /* Note, the target socket must be bound already, else it will not be ready */
+ sax.sa_family = AF_PPPOX;
+ sax.sa_protocol = PX_PROTO_OL2TP;
+ sax.pppol2tp.fd = tunnel_fd;
+ sax.pppol2tp.addr.sin_addr.s_addr = addr->sin_addr.s_addr;
+ sax.pppol2tp.addr.sin_port = addr->sin_port;
+ sax.pppol2tp.addr.sin_family = AF_INET;
+ sax.pppol2tp.s_tunnel = tunnel_id;
+ sax.pppol2tp.s_session = session_id;
+ sax.pppol2tp.d_tunnel = peer_tunnel_id;
+ sax.pppol2tp.d_session = peer_session_id;
- /* session_fd is the fd of the session's PPPoL2TP socket.
- * tunnel_fd is the fd of the tunnel UDP socket.
- */
- fd = connect(session_fd, (struct sockaddr *)&sax, sizeof(sax));
- if (fd < 0 ) {
- return -errno;
- }
- return 0;
+ /* session_fd is the fd of the session's PPPoL2TP socket.
+ * tunnel_fd is the fd of the tunnel UDP socket.
+ */
+ fd = connect(session_fd, (struct sockaddr *)&sax, sizeof(sax));
+ if (fd < 0 ) {
+ return -errno;
+ }
+ return 0;
Internal Implementation
=======================
--
2.25.4
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