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Openwrt Logo.svg
OpenWrt 15.05 ("Chaos Calmer") login screen
Developer OpenWrt Project
Written in {{#property:p277}}
OS family Unix-like
Working state Current
Source model Open source
Initial release January 2004 (2004-01)
Latest release 15.05.1 (Chaos Calmer) (March 16, 2016; 2 years ago (2016-03-16)) [±][1]
Latest preview 15.05-rc3 Chaos Calmer (15 July 2015; 3 years ago (2015-07-15)) [±][2]
Available in 22 languages[3]
Update method opkg
Package manager opkg
Platforms 50 different platforms using the following Instruction sets: AVR32, ARM, CRIS, m68k, MIPS, PowerPC, SPARC, SuperH, Ubicom32, x86, x86-64[4]
Kernel type Monolithic (Linux)
Userland BusyBox, GNU
Default user interface CLI, WebUIs
License Free software (GPL and other licenses)
Official website

OpenWrt is an embedded operating system based on the Linux kernel, primarily used on embedded devices to route network traffic. The main components are the Linux kernel, util-linux, uClibc or musl,[5] and BusyBox. All components have been optimized for size, to be small enough for fitting into the limited storage and memory available in home routers.

OpenWrt is configured using a command-line interface (ash shell), or a web interface (LuCI). There are about 3500 optional software packages available for installation via the opkg package management system.

OpenWrt can run on various types of devices, including CPE routers, residential gateways, smartphones, pocket computers (e.g. Ben NanoNote), and laptops. It is also possible to run OpenWrt on ordinary computers, which are most commonly based on the x86 architecture.


The project came into being because Linksys built the firmware for their WRT54G series of wireless routers from publicly available code licensed under the GPL.[6] Under the terms of that license, Linksys was required to make the source code of its modified version available under the same license,[7][8] which in turn enabled independent developers to create additional derivative versions. Support was originally limited to the WRT54G series, but has since been expanded to include many other chipsets, manufacturers and device types, including Plug Computers and Openmoko mobile phones.

Using this code as a base and later as a reference, developers created a Linux distribution that offers many features not previously found in consumer-level routers. Some features formerly required proprietary software. Before the introduction of OpenWrt 8.09, using Linux 2.6.25 and the b43 kernel module, WLAN for many Broadcom-based routers was only available through the proprietary wl.o module that was also provided for Linux kernel version 2.4.x only.

The code names of OpenWrt branches are named after alcoholic beverages, usually including their recipes in the MOTD as well, cf. White Russian, Kamikaze, Backfire, Attitude Adjustment, Barrier Breaker.

The bleeding edge development trunk was confusingly also called Kamikaze until February 2011 but with r25514 it was renamed as "Attitude Adjustment" and is now being constantly renamed to the next stable name.


Tagged Code Name Version Release date Linux kernel C standard library Binary packages Source packages Notes
(default) (available)
N/A Old version, no longer supported: pre Buildroot-NG 0.x N/A N/A uClibc 474 ≈ 310
r6268 Old version, no longer supported: White Russian 0.9 January 2006 2.4.30 uClibc ≈ 360 ≈ 140 NVRAM-based, nas, wl. Supported platform: brcm-2.4.
r7428 Old version, no longer supported: Kamikaze 7.06 June 2007 2.6.19 uClibc ≈ 750 ≈ 450 Using opkg. Supported platforms: atheros-2.6, au1000-2.6, brcm-2.4, brcm47xx-2.6, ixp4xx-2.6, imagicbox-2.6, rb532-2.6 and x86-2.6.
r7832 Old version, no longer supported: Kamikaze 7.07 July 2007 2.6.21 uClibc ≈ 790 ≈ 475 New platform: amcc-2.6.
r8679 Old version, no longer supported: Kamikaze 7.09 September 2007 2.6.21 uClibc ≈ 630 ≈ 500
r14547 Old version, no longer supported: Kamikaze 8.09 September 2008 2.6.26 uClibc ≈ 1,400 ≈ 875 New platform: ar71xx.
r16279 Old version, no longer supported: Kamikaze 8.09.1 June 2009 2.6.26 uClibc ≈ 1,400 ≈ 875
r18961 Old version, no longer supported: Kamikaze 8.09.2 January 10, 2010[9] 2.6.26 uClibc ≈ 1,400 ≈ 875
r20742 Old version, no longer supported: Backfire 10.03 April 7, 2010[10] 2.6.32 uClibc ≈ 2,350 ≈ 1,050 Supported platforms: adm5120_mips, adm5120_mipsel, ar7, ar71xx, atheros, au1000, avr32, brcm-2.4, brcm47xx, brcm63xx, cobalt, ep80579, ifxmips, ixp4xx, kirkwood, octeon, orion, ppc40x, ppc44x, rb532, rdc, x86 and xburst.
r29594 Old version, no longer supported: Backfire 10.03.1 December 21, 2011[11] 2.6.32 uClibc eglibc
≈ 2,950 ≈ 1,175
r36088 Old version, no longer supported: Attitude Adjustment 12.09 April 25, 2013[12] 3.3 uClibc eglibc ≈ 3,450 ≈ 1,150 CoDel (network scheduler) backported from Linux 3.5 to 3.3. New platforms: ramips, bcm2708 (Raspberry Pi) and others.
r42625 Old version, no longer supported: Barrier Breaker 14.07 October 2, 2014[13] 3.10.49[14] uClibc musl
? ? New platforms: i.MX23, i.MX6[15] and mvebu.
r46767 Old version, no longer supported: Chaos Calmer 15.05 September 11, 2015[16] 3.18.20[17] uClibc musl
? ? nftables (available since Linux kernel 3.12); New platforms: TBA if any
Current stable version: Chaos Calmer 15.05.1 March 16, 2016[19] 3.18.23
trunk Future release: Designated Driver[20] development N/A ≥4.1 musl[21] uClibc
? ?
Old version
Older version, still supported
Latest version
Latest preview version
Future release

Hardware incompatibilities

With the Attitude Adjustment (12.09) release of OpenWrt, all hardware devices with 16 MB or less RAM are no longer supported as they can run out of memory easily. Older Backfire (10.03) is recommended instead for bcm47xx devices, as issues for those devices came from dropping support for the legacy Broadcom target brcm-2.4.[22][23]


OpenWrt follows the bazaar-philosophy and is known for an abundance of options. Features include:

Web interface

Before release 8.09, OpenWrt had a minimal web interface. In OpenWrt releases 8.09 and newer, a more capable web interface is included.[30] This interface is based on LuCI, an MVC framework written in the Lua programming language.[29]

The X-Wrt project provides an alternative web interface, named webif² in the package repositories, for the current and previous versions of OpenWrt.

The Gargoyle Router Management Utility is a web interface for OpenWrt with a strong emphasis on usability. It was originally available as a set of packages for OpenWrt. As the author of Gargoyle started to make modifications to the base system layout of OpenWrt, the package system was dropped and only complete firmware images are now[when?] available for download. Gargoyle makes extensive use of JavaScript to offload as much work as possible to the client computer, and is focused on ease of use, striving to reach a level comparable to the appliance feeling of commercial router firmware.



OpenWrt's development environment and build system, known together as OpenWrt Buildroot, are based on a heavily modified Buildroot system. OpenWrt Buildroot is a set of Makefiles and patches that automates the process of building a complete Linux-based OpenWrt system for an embedded device, by building and using an appropriate cross-compilation toolchain.[31][32]

Embedded devices usually use a different processor than the one found in host computers used for building their OpenWrt system images, requiring a cross-compilation toolchain. Such a compilation toolchain runs on a host system, but generates code for a targeted embedded device and its processor's instruction set architecture (ISA). For example, if a host system uses x86 and a target system uses MIPS32, the regular compilation toolchain of the host runs on x86 and generates code for x86 architecture, while the cross-compilation toolchain runs on x86 and generates code for the MIPS32 architecture. OpenWrt Buildroot automates this whole process to work on the instruction set architectures of most embedded devices and host systems.[31][33]

OpenWrt Buildroot provides the following features:[31][33]

  • Makes it easy to port software across architectures
  • Uses kconfig (Linux kernel menuconfig) for the configuration of all options
  • Provides an integrated cross-compiler toolchain (gcc, ld, uClibc etc.)
  • Provides an abstraction for autotools (automake, autoconf), cmake and SCons
  • Handles standard OpenWrt image build workflow: downloading, patching, configuration, compilation and packaging
  • Provides a number of common fixes for known badly behaving packages

Besides building system images, OpenWrt development environment also provides a mechanism for simplified cross-platform building of OpenWrt software packages. Source code for each software package is required to provide a Makefile-like set of building instructions, and an optional set of patches for bug fixes or footprint optimizations.[34]


OpenWrt, especially its Buildroot build system, has been adopted many times:

  • Freifunk and other mesh network communities
  • (Cerowrt)
  • IETF IPv6 integration projects HIPnet and HomeNet are OpenWrt-based


  • LEDE is founded as a spin-off of the OpenWrt project and shares many of the same goals.
  • CeroWrt – with a purpose to complement the debloat-testing kernel tree and provide a platform for real-world testing of bufferbloat fixes[35][36]
  • Coova chilli – OpenWrt-based with focus on wireless hotspots, a fork of chillifire with focus on wireless hotspot management
  • Gargoyle – a web interface for OpenWrt with a strong emphasis on usability that later forked into a separate distribution
  • Flukso – Wireless sensor nodes using an Atheros AR2317 chipset running a patched OpenWrt OS for communication. Sources and hardware schematics available on GitHub.
  • FON – OpenWrt-based wireless routers acting as hotspots. Sources and toolchain available on
  • Linino – OpenWrt-based distribution for the MIPS-based Arduino Yùn: GitHub Project
  • Midge Linux – an OpenWrt-based distribution for devices based on Infineon Technologies ADM-5120 SoCs, such as Edimax BR-6104K and BR-6104KP.
  • OpenSAN – iSCSI target Storage Area Network realization.
  • PacketProtector – OpenWrt-based security distribution that includes IDS, IPS, VPN, and web antivirus capabilities. Packages included Snort, Snort-inline, FreeRADIUS, OpenVPN, DansGuardian and ClamAV. These tools were accessible via the old web GUI management interface of OpenWrt, called X-Wrt or webif^2. Project ended on June 7, 2012.[37]
  • The Turris Omnia router runs on an OpenWrt derivative
  • Diverse grassroots projects for wireless community networks, including Freifunk, Libre-Mesh and qMp
  • libreCMC – OpenWrt-based distribution without non-free software or binary blobs, endorsed by the Free Software Foundation[38]


  1. "Chaos Calmer 15.05.1". 16 March 2016. Retrieved 21 March 2016. 
  2. "Chaos Calmer 15.05-rc3". OpenWrt Forum. 13 June 2015. Retrieved 13 June 2015. 
  3. "LuCI Translation Portal". 2004-09-01. Retrieved 2010-12-31. 
  4. " in trunk/target – OpenWrt". 2013-11-22. Retrieved 2014-02-13. 
  5. Fietkau, Felix (16 June 2015). "OpenWrt switches to musl by default". Retrieved 16 June 2015. 
  6. Linksys WRT54G and the GPL on lkml (7 Jun 2003)
  7. The Open Source WRT54G Story By Aaron Weiss (November 08, 2005)
  8. Linksys Releases GPLed Code for WRT54G on slashdot (July 2003)
  9. "Release Notes Kamikaze 8.09.2". 2010-01-10. Retrieved 2013-04-26. 
  10. "Release Notes Backfire 10.03". 2010-04-07. Retrieved 2013-04-26. 
  11. "Release Notes Backfire 10.03.1". 2011-12-21. Retrieved 2013-04-26. 
  12. "Release Notes Attitude Adjustment 12.09". 2013-04-25. Retrieved 2013-04-26. 
  13. "OpenWrt BarrierBreaker 14.07". October 2014. 
  14. "kernel: update to 3.10.49 – OpenWrt". 2014-07-20. 
  15. Freescale i.MX support
  16. "OpenWrt Chaos Calmer 15.05". September 2015. 
  17. "[OpenWrt-Devel] Chaos Calmer 15.05-rc3". 2015-07-16. 
  18. "[OpenWrt-Devel] [PATCH 1/2] toolchain: The glorious return of glibc, ver 2.21". 2015-03-11. 
  19. "Chaos Calmer 15.05.1". 16 March 2016. Retrieved 21 March 2016. 
  20. "Changeset 46846: change banner to Designated Driver release". 2015-09-11. 
  21. "[OpenWrt-Devel] OpenWrt switches to musl by default". 2015-06-16. 
  22. "Release Notes for Attitude Adjustment (12.09 final)". 2013-04-25. Retrieved 2013-09-26. 
  23. "OpenWrt: Table of Hardware". Retrieved 2013-09-26. 
  24. "Debating overlayfs". June 15, 2011. 
  25. "OpenWrt partition layout". 
  26. "OpenWrt Unified Configuration Interface". 
  27. freecwmp is a CWMP client for OpenWrt
  28. "Changeset 31756 – OpenWrt". 2012-05-16. Retrieved 2014-02-13. 
  29. 29.0 29.1 "LuCI project". Retrieved February 28, 2009. 
  30. "OpenWrt 8.09 release notes". Retrieved February 23, 2009. 
  31. 31.0 31.1 31.2 "OpenWrt Buildroot – About". Retrieved 2013-10-21. 
  32. "OpenWrt Buildroot - Usage and documentation". 2006-01-08. Retrieved 2013-10-21. 
  33. 33.0 33.1 Tao Jin (2012-02-13). "OpenWrt Development Guide" (PDF). Wireless Networks Lab, CCIS, NEU. Retrieved 2013-10-21. 
  34. "Creating packages". Retrieved 2013-10-21. 
  35. "CeroWrt Wiki". Retrieved 2015-09-16. 
  36. "ANNOUNCE: debloat-testing kernel git tree". Retrieved 2014-02-13. 
  37. ""closing time" message from author on PacketProtector forum". 
  38. "Free Software Foundation adds libreCMC to its list of endorsed distributions". 2014-09-04. Retrieved 2014-12-21. 

External links