forked from luck/tmp_suning_uos_patched
docs: networking: convert tuntap.txt to ReST
- add SPDX header; - use copyright symbol; - adjust titles and chapters, adding proper markups; - mark code blocks and literals as such; - adjust identation, whitespaces and blank lines where needed; - 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
David S. Miller
parent
ef891284b1
commit
973d55e590
|
|
@ -111,6 +111,7 @@ Contents:
|
|||
team
|
||||
timestamping
|
||||
tproxy
|
||||
tuntap
|
||||
|
||||
.. only:: subproject and html
|
||||
|
||||
|
|
|
|||
|
|
@ -1,20 +1,28 @@
|
|||
Universal TUN/TAP device driver.
|
||||
Copyright (C) 1999-2000 Maxim Krasnyansky <max_mk@yahoo.com>
|
||||
.. SPDX-License-Identifier: GPL-2.0
|
||||
.. include:: <isonum.txt>
|
||||
|
||||
Linux, Solaris drivers
|
||||
Copyright (C) 1999-2000 Maxim Krasnyansky <max_mk@yahoo.com>
|
||||
===============================
|
||||
Universal TUN/TAP device driver
|
||||
===============================
|
||||
|
||||
FreeBSD TAP driver
|
||||
Copyright (c) 1999-2000 Maksim Yevmenkin <m_evmenkin@yahoo.com>
|
||||
Copyright |copy| 1999-2000 Maxim Krasnyansky <max_mk@yahoo.com>
|
||||
|
||||
Linux, Solaris drivers
|
||||
Copyright |copy| 1999-2000 Maxim Krasnyansky <max_mk@yahoo.com>
|
||||
|
||||
FreeBSD TAP driver
|
||||
Copyright |copy| 1999-2000 Maksim Yevmenkin <m_evmenkin@yahoo.com>
|
||||
|
||||
Revision of this document 2002 by Florian Thiel <florian.thiel@gmx.net>
|
||||
|
||||
1. Description
|
||||
TUN/TAP provides packet reception and transmission for user space programs.
|
||||
==============
|
||||
|
||||
TUN/TAP provides packet reception and transmission for user space programs.
|
||||
It can be seen as a simple Point-to-Point or Ethernet device, which,
|
||||
instead of receiving packets from physical media, receives them from
|
||||
user space program and instead of sending packets via physical media
|
||||
writes them to the user space program.
|
||||
instead of receiving packets from physical media, receives them from
|
||||
user space program and instead of sending packets via physical media
|
||||
writes them to the user space program.
|
||||
|
||||
In order to use the driver a program has to open /dev/net/tun and issue a
|
||||
corresponding ioctl() to register a network device with the kernel. A network
|
||||
|
|
@ -33,41 +41,51 @@ Copyright (C) 1999-2000 Maxim Krasnyansky <max_mk@yahoo.com>
|
|||
br_sigio.c - bridge based on async io and SIGIO signal.
|
||||
However, the best example is VTun http://vtun.sourceforge.net :))
|
||||
|
||||
2. Configuration
|
||||
Create device node:
|
||||
2. Configuration
|
||||
================
|
||||
|
||||
Create device node::
|
||||
|
||||
mkdir /dev/net (if it doesn't exist already)
|
||||
mknod /dev/net/tun c 10 200
|
||||
|
||||
Set permissions:
|
||||
|
||||
Set permissions::
|
||||
|
||||
e.g. chmod 0666 /dev/net/tun
|
||||
There's no harm in allowing the device to be accessible by non-root users,
|
||||
since CAP_NET_ADMIN is required for creating network devices or for
|
||||
connecting to network devices which aren't owned by the user in question.
|
||||
If you want to create persistent devices and give ownership of them to
|
||||
unprivileged users, then you need the /dev/net/tun device to be usable by
|
||||
those users.
|
||||
|
||||
There's no harm in allowing the device to be accessible by non-root users,
|
||||
since CAP_NET_ADMIN is required for creating network devices or for
|
||||
connecting to network devices which aren't owned by the user in question.
|
||||
If you want to create persistent devices and give ownership of them to
|
||||
unprivileged users, then you need the /dev/net/tun device to be usable by
|
||||
those users.
|
||||
|
||||
Driver module autoloading
|
||||
|
||||
Make sure that "Kernel module loader" - module auto-loading
|
||||
support is enabled in your kernel. The kernel should load it on
|
||||
first access.
|
||||
|
||||
Manual loading
|
||||
insert the module by hand:
|
||||
modprobe tun
|
||||
|
||||
Manual loading
|
||||
|
||||
insert the module by hand::
|
||||
|
||||
modprobe tun
|
||||
|
||||
If you do it the latter way, you have to load the module every time you
|
||||
need it, if you do it the other way it will be automatically loaded when
|
||||
/dev/net/tun is being opened.
|
||||
|
||||
3. Program interface
|
||||
3.1 Network device allocation:
|
||||
3. Program interface
|
||||
====================
|
||||
|
||||
char *dev should be the name of the device with a format string (e.g.
|
||||
"tun%d"), but (as far as I can see) this can be any valid network device name.
|
||||
Note that the character pointer becomes overwritten with the real device name
|
||||
(e.g. "tun0")
|
||||
3.1 Network device allocation
|
||||
-----------------------------
|
||||
|
||||
``char *dev`` should be the name of the device with a format string (e.g.
|
||||
"tun%d"), but (as far as I can see) this can be any valid network device name.
|
||||
Note that the character pointer becomes overwritten with the real device name
|
||||
(e.g. "tun0")::
|
||||
|
||||
#include <linux/if.h>
|
||||
#include <linux/if_tun.h>
|
||||
|
|
@ -78,45 +96,51 @@ Copyright (C) 1999-2000 Maxim Krasnyansky <max_mk@yahoo.com>
|
|||
int fd, err;
|
||||
|
||||
if( (fd = open("/dev/net/tun", O_RDWR)) < 0 )
|
||||
return tun_alloc_old(dev);
|
||||
return tun_alloc_old(dev);
|
||||
|
||||
memset(&ifr, 0, sizeof(ifr));
|
||||
|
||||
/* Flags: IFF_TUN - TUN device (no Ethernet headers)
|
||||
* IFF_TAP - TAP device
|
||||
/* Flags: IFF_TUN - TUN device (no Ethernet headers)
|
||||
* IFF_TAP - TAP device
|
||||
*
|
||||
* IFF_NO_PI - Do not provide packet information
|
||||
*/
|
||||
ifr.ifr_flags = IFF_TUN;
|
||||
* IFF_NO_PI - Do not provide packet information
|
||||
*/
|
||||
ifr.ifr_flags = IFF_TUN;
|
||||
if( *dev )
|
||||
strncpy(ifr.ifr_name, dev, IFNAMSIZ);
|
||||
strncpy(ifr.ifr_name, dev, IFNAMSIZ);
|
||||
|
||||
if( (err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0 ){
|
||||
close(fd);
|
||||
return err;
|
||||
close(fd);
|
||||
return err;
|
||||
}
|
||||
strcpy(dev, ifr.ifr_name);
|
||||
return fd;
|
||||
}
|
||||
|
||||
3.2 Frame format:
|
||||
If flag IFF_NO_PI is not set each frame format is:
|
||||
}
|
||||
|
||||
3.2 Frame format
|
||||
----------------
|
||||
|
||||
If flag IFF_NO_PI is not set each frame format is::
|
||||
|
||||
Flags [2 bytes]
|
||||
Proto [2 bytes]
|
||||
Raw protocol(IP, IPv6, etc) frame.
|
||||
|
||||
3.3 Multiqueue tuntap interface:
|
||||
3.3 Multiqueue tuntap interface
|
||||
-------------------------------
|
||||
|
||||
From version 3.8, Linux supports multiqueue tuntap which can uses multiple
|
||||
file descriptors (queues) to parallelize packets sending or receiving. The
|
||||
device allocation is the same as before, and if user wants to create multiple
|
||||
queues, TUNSETIFF with the same device name must be called many times with
|
||||
IFF_MULTI_QUEUE flag.
|
||||
From version 3.8, Linux supports multiqueue tuntap which can uses multiple
|
||||
file descriptors (queues) to parallelize packets sending or receiving. The
|
||||
device allocation is the same as before, and if user wants to create multiple
|
||||
queues, TUNSETIFF with the same device name must be called many times with
|
||||
IFF_MULTI_QUEUE flag.
|
||||
|
||||
char *dev should be the name of the device, queues is the number of queues to
|
||||
be created, fds is used to store and return the file descriptors (queues)
|
||||
created to the caller. Each file descriptor were served as the interface of a
|
||||
queue which could be accessed by userspace.
|
||||
``char *dev`` should be the name of the device, queues is the number of queues
|
||||
to be created, fds is used to store and return the file descriptors (queues)
|
||||
created to the caller. Each file descriptor were served as the interface of a
|
||||
queue which could be accessed by userspace.
|
||||
|
||||
::
|
||||
|
||||
#include <linux/if.h>
|
||||
#include <linux/if_tun.h>
|
||||
|
|
@ -127,7 +151,7 @@ Copyright (C) 1999-2000 Maxim Krasnyansky <max_mk@yahoo.com>
|
|||
int fd, err, i;
|
||||
|
||||
if (!dev)
|
||||
return -1;
|
||||
return -1;
|
||||
|
||||
memset(&ifr, 0, sizeof(ifr));
|
||||
/* Flags: IFF_TUN - TUN device (no Ethernet headers)
|
||||
|
|
@ -140,30 +164,30 @@ Copyright (C) 1999-2000 Maxim Krasnyansky <max_mk@yahoo.com>
|
|||
strcpy(ifr.ifr_name, dev);
|
||||
|
||||
for (i = 0; i < queues; i++) {
|
||||
if ((fd = open("/dev/net/tun", O_RDWR)) < 0)
|
||||
goto err;
|
||||
err = ioctl(fd, TUNSETIFF, (void *)&ifr);
|
||||
if (err) {
|
||||
close(fd);
|
||||
goto err;
|
||||
}
|
||||
fds[i] = fd;
|
||||
if ((fd = open("/dev/net/tun", O_RDWR)) < 0)
|
||||
goto err;
|
||||
err = ioctl(fd, TUNSETIFF, (void *)&ifr);
|
||||
if (err) {
|
||||
close(fd);
|
||||
goto err;
|
||||
}
|
||||
fds[i] = fd;
|
||||
}
|
||||
|
||||
return 0;
|
||||
err:
|
||||
for (--i; i >= 0; i--)
|
||||
close(fds[i]);
|
||||
close(fds[i]);
|
||||
return err;
|
||||
}
|
||||
|
||||
A new ioctl(TUNSETQUEUE) were introduced to enable or disable a queue. When
|
||||
calling it with IFF_DETACH_QUEUE flag, the queue were disabled. And when
|
||||
calling it with IFF_ATTACH_QUEUE flag, the queue were enabled. The queue were
|
||||
enabled by default after it was created through TUNSETIFF.
|
||||
A new ioctl(TUNSETQUEUE) were introduced to enable or disable a queue. When
|
||||
calling it with IFF_DETACH_QUEUE flag, the queue were disabled. And when
|
||||
calling it with IFF_ATTACH_QUEUE flag, the queue were enabled. The queue were
|
||||
enabled by default after it was created through TUNSETIFF.
|
||||
|
||||
fd is the file descriptor (queue) that we want to enable or disable, when
|
||||
enable is true we enable it, otherwise we disable it
|
||||
fd is the file descriptor (queue) that we want to enable or disable, when
|
||||
enable is true we enable it, otherwise we disable it::
|
||||
|
||||
#include <linux/if.h>
|
||||
#include <linux/if_tun.h>
|
||||
|
|
@ -175,53 +199,61 @@ Copyright (C) 1999-2000 Maxim Krasnyansky <max_mk@yahoo.com>
|
|||
memset(&ifr, 0, sizeof(ifr));
|
||||
|
||||
if (enable)
|
||||
ifr.ifr_flags = IFF_ATTACH_QUEUE;
|
||||
ifr.ifr_flags = IFF_ATTACH_QUEUE;
|
||||
else
|
||||
ifr.ifr_flags = IFF_DETACH_QUEUE;
|
||||
ifr.ifr_flags = IFF_DETACH_QUEUE;
|
||||
|
||||
return ioctl(fd, TUNSETQUEUE, (void *)&ifr);
|
||||
}
|
||||
|
||||
Universal TUN/TAP device driver Frequently Asked Question.
|
||||
|
||||
Universal TUN/TAP device driver Frequently Asked Question
|
||||
=========================================================
|
||||
|
||||
1. What platforms are supported by TUN/TAP driver ?
|
||||
|
||||
Currently driver has been written for 3 Unices:
|
||||
Linux kernels 2.2.x, 2.4.x
|
||||
FreeBSD 3.x, 4.x, 5.x
|
||||
Solaris 2.6, 7.0, 8.0
|
||||
|
||||
- Linux kernels 2.2.x, 2.4.x
|
||||
- FreeBSD 3.x, 4.x, 5.x
|
||||
- Solaris 2.6, 7.0, 8.0
|
||||
|
||||
2. What is TUN/TAP driver used for?
|
||||
As mentioned above, main purpose of TUN/TAP driver is tunneling.
|
||||
|
||||
As mentioned above, main purpose of TUN/TAP driver is tunneling.
|
||||
It is used by VTun (http://vtun.sourceforge.net).
|
||||
|
||||
Another interesting application using TUN/TAP is pipsecd
|
||||
(http://perso.enst.fr/~beyssac/pipsec/), a userspace IPSec
|
||||
implementation that can use complete kernel routing (unlike FreeS/WAN).
|
||||
|
||||
3. How does Virtual network device actually work ?
|
||||
3. How does Virtual network device actually work ?
|
||||
|
||||
Virtual network device can be viewed as a simple Point-to-Point or
|
||||
Ethernet device, which instead of receiving packets from a physical
|
||||
media, receives them from user space program and instead of sending
|
||||
packets via physical media sends them to the user space program.
|
||||
Ethernet device, which instead of receiving packets from a physical
|
||||
media, receives them from user space program and instead of sending
|
||||
packets via physical media sends them to the user space program.
|
||||
|
||||
Let's say that you configured IPv6 on the tap0, then whenever
|
||||
the kernel sends an IPv6 packet to tap0, it is passed to the application
|
||||
(VTun for example). The application encrypts, compresses and sends it to
|
||||
(VTun for example). The application encrypts, compresses and sends it to
|
||||
the other side over TCP or UDP. The application on the other side decompresses
|
||||
and decrypts the data received and writes the packet to the TAP device,
|
||||
and decrypts the data received and writes the packet to the TAP device,
|
||||
the kernel handles the packet like it came from real physical device.
|
||||
|
||||
4. What is the difference between TUN driver and TAP driver?
|
||||
|
||||
TUN works with IP frames. TAP works with Ethernet frames.
|
||||
|
||||
This means that you have to read/write IP packets when you are using tun and
|
||||
ethernet frames when using tap.
|
||||
|
||||
5. What is the difference between BPF and TUN/TAP driver?
|
||||
|
||||
BPF is an advanced packet filter. It can be attached to existing
|
||||
network interface. It does not provide a virtual network interface.
|
||||
A TUN/TAP driver does provide a virtual network interface and it is possible
|
||||
to attach BPF to this interface.
|
||||
|
||||
6. Does TAP driver support kernel Ethernet bridging?
|
||||
Yes. Linux and FreeBSD drivers support Ethernet bridging.
|
||||
|
||||
Yes. Linux and FreeBSD drivers support Ethernet bridging.
|
||||
|
|
@ -17161,7 +17161,7 @@ TUN/TAP driver
|
|||
M: Maxim Krasnyansky <maxk@qti.qualcomm.com>
|
||||
S: Maintained
|
||||
W: http://vtun.sourceforge.net/tun
|
||||
F: Documentation/networking/tuntap.txt
|
||||
F: Documentation/networking/tuntap.rst
|
||||
F: arch/um/os-Linux/drivers/
|
||||
|
||||
TURBOCHANNEL SUBSYSTEM
|
||||
|
|
|
|||
|
|
@ -355,7 +355,7 @@ config TUN
|
|||
devices, driver will automatically delete tunXX or tapXX device and
|
||||
all routes corresponding to it.
|
||||
|
||||
Please read <file:Documentation/networking/tuntap.txt> for more
|
||||
Please read <file:Documentation/networking/tuntap.rst> for more
|
||||
information.
|
||||
|
||||
To compile this driver as a module, choose M here: the module
|
||||
|
|
|
|||
Loading…
Reference in New Issue
Block a user