WinDivert 1.1: Windows Packet Divert
====================================
1. Introduction
---------------
Windows Packet Divert (WinDivert) is a user-mode packet capture-and-divert
package for Windows Vista, Windows 2008, Windows 7, and Windows 8.
With WinDivert developers can write user-mode programs that capture and
modify or drop network packets sent to/from the Windows network stack.
In summary, WinDivert can
- capture network packets
- filter/drop network packets
- sniff network packets
- (re)inject network packets
- modify network packets
WinDivert can be used to implement user-mode packet filters, packet sniffers,
firewalls, NAT, VPNs, tunneling applications, etc., etc.. If you
need to intercept and modify packets, then WinDivert is for you.
The features of WinDivert include:
- packet interception, sniffing, or dropping modes
- support for loopback (localhost) traffic
- full IPv6 support
- network layer
- simple and powerful API
- high-level filtering language
- filter priorities
- freely available under the terms of the GNU Lesser General Public
License (LGPL)
For more information about WinDivert, see doc/divert.html
2. Similar Packages
-------------------
WinDivert is similar to divert sockets in FreeBSD/MacOS, NETLINK sockets in
Linux, and some commercial packet capturing packages such as WinPkFilter for
Windows. The design of WinDivert is largely influenced by FreeBSD's divert
sockets.
WinDivert in packet-sniffing mode is similar to Winpcap. Unlike Winpcap,
WinDivert fully supports capturing loopback traffic. Furthermore, WinDivert
supports packet interception, which is not supported in Winpcap.
3. Architecture
---------------
The basic architecture of WinDivert is as follows:
+-----------------+
| |
+------->| PROGRAM |--------+
| | (WinDivert.dll) | |
| +-----------------+ |
| | (3) re-injected
| (2a) matching packet | packet
| |
| |
[user mode] | |
....................|...................................|...................
[kernel mode] | |
| |
| |
+---------------+ +----------------->
(1) packet | | (2b) non-matching packet
------------>| WinDivert.sys |-------------------------------------------->
| |
+---------------+
The WinDivert.sys driver is inserted below the Windows network stack. The
following then happens
(1) a new packet enters the network stack and is intercepted by WinDivert.sys
(2a) if the packet matches a PROGRAM-defined filter, it is diverted. The
PROGRAM reads the packet with a call to the WinDivertRecv() function.
(2b) if the packet does not match the filter, the packet is permitted to
continue as normal.
(3) PROGRAM either drops, modifies, or re-injects the packet. If the
(modified) packet is re-injected, via a call to WinDivertSend(), it is
inserted back into the Windows network stack.
4. Building
-----------
(1) In a WinDDK build environment, run the command:
wddk-build.bat
(2) [OPTIONAL Visual Studio 2012 support] In a VS2012 command prompt, run the
command:
msvc-build.bat
(3) [OPTIONAL MinGW support] In Linux with MinGW a cross-compiler, run the
command:
sh mingw-build.sh
For more detailed build instructions, see doc\windivert.html
5. License
----------
This package is distributed under the GNU Lesser General Public License
(LGPL) Version 3. See LICENSE for more information.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>
6. About
--------
WinDivert was written by basil.
For further information, or bug reports, please contact
basil AT reqrypt DOT org
The homepage for WinDivert is
http://reqrypt.org/windivert.html
The source code for WinDivert is hosted by GitHub at
https://github.com/basil00/Divert