OpenWrt (fromopen wireless router) is an open-source project forembedded operating systems based onLinux, primarily used onembedded devices toroute network traffic. The main components are Linux,util-linux,musl,^[5] andBusyBox. All components have been optimized to be small enough to fit into the limited storage and memory available in home routers.

OpenWrt

OpenWrt 18.06.1 login screen
Developer	OpenWrt Project
OS family	Linux (Unix-like)
Working state	Current
Source model	Open source
Initial release	January 2004; 21 years ago (2004-01)
Latest release	24.10.0[1]  / 6 February 2025; 53 days ago (6 February 2025)
Latest preview	24.10.0-rc7[2] / 29 January 2025; 2 months ago (2025-01-29)
Repository	git.openwrt.org
Available in	English, Chinese, Polish, Portuguese, Punjabi, Spanish, Welsh + 25 partially translated languages[3]
Update method	opkg (up to 24.10 release)apk (snapshot builds)
Package manager	Alpine Package Manager (APK)opkg (up to 24.10 release)
Platforms	50 different platforms using the followingInstruction sets:ARC,ARM,m68k,MIPS,PowerPC,SPARC,SuperH,x86,x86-64[4]
Kernel type	Monolithic (Linux)
Userland	BusyBox
Default user interface	CLI, WebUIs (LuCI)
License	Free software (GPL and other licenses)
Official website	openwrt.org

OpenWrt is configured using acommand-line interface (ash shell) or a web interface (LuCI). There are about 8000 optionalsoftware packages available for installation via the opkgpackage management system.

OpenWrt can run on various types of devices, includingCPE routers,residential gateways,smartphones,pocket computers (e.g.,Ben NanoNote). It is also possible to run OpenWrt onpersonal computers andlaptops.

The OpenWrt project was started in 2004 afterLinksys had built thefirmware for theirWRT54G series of wireless routers with code licensed under theGNU General Public License.^[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 enabled independent developers to create derivative versions. Support was originally limited to the WRT54G series, but has since been expanded to include many other routers and devices from many different manufacturers.

Using this code as a base and later as a reference, developers created aLinux distribution that offers many features not previously found in consumer-level routers. Early on some features required proprietary software. For example, prior to OpenWrt 8.09 (based on Linux 2.6.25 and theb43 kernel module) WLAN for manyBroadcom-based routers could only be had via the proprietarywl.o module (and which required Linux 2.4.x).

OpenWrt releases were historically named after cocktails, such asWhite Russian,Kamikaze, Backfire, Attitude Adjustment, Barrier Breaker and Chaos Calmer, and their recipes were included in themessage of the day (motd) displayed after logging in using thecommand-line interface.

In May 2016, OpenWrt was forked by a group of core OpenWrt contributors due to disagreements on internal process.^[9] The fork was dubbedLinux Embedded Development Environment (LEDE). The schism was reconciled a year later.^[10] Following the remerger, announced in January 2018,^[11] the OpenWrt branding is preserved, with many of the LEDE processes and rules used. The LEDE project name was used for v17.01, with development versions of 18.01 branded OpenWrt, dropping the original cocktail based naming scheme.^[12]

TheLinux Embedded Development Environment (LEDE) project was afork of the OpenWrt project and shared many of the same goals.^{[48][49][50][51][52]} It was created in May 2016 by a group of core OpenWrt contributors due to disagreements on OpenWrt internal processes.^[49] The schism was nominally reconciled a year later in May 2017 pending approval of the LEDE developers.^[53] The remerger preserves the OpenWrt branding, but uses many of the LEDE processes and rules. The remerge proposal vote was passed by LEDE developers in June 2017,^[54] and formally announced in January 2018.^[55] The merging process was completed before the OpenWrt 18.06 release.^[56]

OpenWrt features a writeableroot file system, enabling users to modify any file and easily install additional software. This is in contrast with other firmware based on read-only file systems which don't allow modifying installed software without rebuilding and flashing a complete firmware image. This is accomplished by overlaying a read-only compressedSquashFS file system with a writeableJFFS2 file system usingoverlayfs.^[64][65] Additional software can be installed with theopkg package manager and the package repository contains approximately 8000 packages (by 2022).

OpenWrt can be configured through either acommand-line interface or a web interface called LuCI. OpenWrt provides set of scripts called UCI (unified configuration interface) to unify and simplify configuration through the command-line interface.^[66] Additional web interfaces, such asGargoyle, are also available.

OpenWrt provides regular bug fixes and security updates even for devices that are no longer supported by their manufacturers.

OpenWrt provides exhaustive possibilities to configure common network-related features, likeIPv4,IPv6,DNS,DHCP,routing,firewall,NAT,port forwarding andWPA.

Other features include:

• Extensible configuration of the entire hardware drivers, e.g. built-innetwork switches and theirVLAN-capabilities,WNICs,DSL modems,FX, available hardware buttons, etc.
• Mesh networking throughB.A.T.M.A.N.,OLSR andIEEE 802.11s-capabilities of theWNIC drivers and other ad hoc mesh routing protocols that have been implemented within Linux.
• Wireless functionality, e.g. make the device act as awireless repeater, awireless access point, awireless bridge, acaptive portal, or a combination of these with e.g.ChilliSpot,WiFiDog Captive Portal, etc.
• Wireless security:Packet injection, e.g.Airpwn,lorcon, e.a.
• Dynamically configured port forwarding protocolsPCP,NAT-PMP, andUPnP IGD
• Port knocking
• TR-069 (CWMP) client^[67]
• IPS viaSnort
• Active queue management (AQM) through thenetwork scheduler of the Linux kernel, with many availablequeuing disciplines.CoDel has been backported to Kernel 3.3.^[68] This encapsulatesTraffic shaping to ensure fair distribution of bandwidth among multiple users andquality of service (QoS) for simultaneous use of applications such asVoIP,online gaming, andstreaming media without experiencing the negative impacts of link saturation.
• Load balancing for use with multipleISPs usingsource-specific routing
• IP tunneling (GRE, OpenVPN, pseudowire,WireGuard, etc.)
• Extensible realtimenetwork monitoring and statistics through e.g.RRDtool,Collectd,Nagios,Munin lite,Zabbix, etc.
• Dynamic DNS services to maintain a fixed domain name with anISP that does not provide a staticIP address
• OpenWrt supports any hardware that has Linux support; devices that can be connected (e.g. overUSB) include
  • Printers
  • Mobile broadband modems
  • Webcams
  • Sound cards
• Notable software packages to use the hardware support are
  • File sharing viaSAMBA, (Windows-compatible),NFS,FTP, SFTP. Printer sharing over theprint serverCUPS (spooling) orp910nd (non-spooling)
  • PulseAudio,Music Player Daemon, Audio/Video streaming viaDLNA/UPnP AV standards,iTunes (DAAP) server
  • Asterisk (PBX)
  • MQ Telemetry Transport throughMosquitto

OpenWrt's development environment and build system, known together asOpenWrt Buildroot, are based on a heavily modifiedBuildroot system. OpenWrt Buildroot is a set ofMakefiles andpatches that automates the process of building a complete Linux-based OpenWrt system for an embedded device, by building and using an appropriatecross-compilationtoolchain.^[69][70]

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'sinstruction set architecture (ISA). For example, if a host system usesx86 and a target system usesMIPS32, the regular compilation toolchain of the host runs on x86 and generates code for x86 architecture,^[71] 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.^[69][72]

OpenWrt Buildroot provides the following features:^[69][72]

• Makes it easy to port software across architectures
• Uses kconfig (Linux kernelmenuconfig) for the configuration of all options
• Provides an integrated cross-compiler toolchain (gcc,ld,uClibc etc.)
• Provides an abstraction forautotools (automake,autoconf),CMake andSCons
• 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.^[73]

OpenWrt runs many different routers and includes a table of compatible hardware on its website.^[74] In its buyer's guide,^[75] it notes that users recommend devices equipped with wireless chips from either Qualcomm'sAtheros, Ralink (nowMediaTek) or any vendor with open source drivers and specifications. It specifically avoidsBroadcom chipsets as the feature set is very limited due to having no open drivers. OpenWrt also recommends choosing a device with a minimum of 16 MB of flash and 128 MB of RAM, preferably higher amounts.^[76]

OpenWrt, especially its Buildroot build system, has been adopted as the structure for other efforts. For example

• AltiWi "one-time-fee-only" replacement for Cloudtrax.
• Bufferbloat.net (Cerowrt)
• Freifunk and other mesh network communities
• IETF IPv6 integration projects HIPnet and HomeNet are OpenWrt-based
• prplOS, carrier-grade framework designed to powerISPs routers and gateways made byPrpl Foundation
• SIMET Box, developed byNIC.br, is OpenWrt-based^[77]

• AREDN TheAmateur Radio Emergency Data Network uses a firmware based on OpenWrt:GitHub Project
• CeroWrt – (2011—2014) project to resolve bufferbloat in home networking, support IPv6, integrate DNSSEC, for wired and wireless, to complement the debloat-testing kernel tree and provide a platform for real-world testing ofbufferbloat fixes.^[78] The CeroWRT project is completely by 2014, when the finalized fixes were merged into OpenWRT. The "Bufferbloat project" behind CeroWRT went on to research new methods such asCAKE.^[79]
• Coova chilli – OpenWrt-based with focus on wireless hotspots, a fork of chillifire with focus on wireless hotspot management
• Flukso – Wireless sensor nodes using an Atheros AR2317 chipset running a patched OpenWrt OS for communication. Sources and hardware schematics available onGitHub.
• Fon – OpenWrt-based wireless routers acting as hotspots. Sources and toolchain available on fonosfera.org
• Gargoyle – a web interface for OpenWrt with a strong emphasis on usability that later forked into a separate distribution
• Gluon – Framework for building OpenWrt-based firmwares fitted formesh network deployment:GitHub Project
• JUCIWRT – a modern distribution using the JUCI webgui that later became an OpenWrt feed instead. The source code for JUCI is available atmkschreder/juci and is still usable by installing openwrt feed found atmkschreder/juci-openwrt-feed
• libreCMC – OpenWrt-based distribution which excludes non-free software or binary blobs, endorsed by theFree Software Foundation^[80]
• LibreMesh – Framework for creating OpenWrt-based firmwares for wireless mesh nodes.GitHub Project
• Linino – OpenWrt-based distribution for theMIPS-basedArduino Yùn:GitHub Project
• Midge Linux – an OpenWrt-based distribution for devices based onInfineon Technologies ADM-5120SoCs, such as Edimax BR-6104K and BR-6104KP.
• OpenMPTCProuter – aggregation of multiple Internet connections usingMultipath TCP
• OpenSAN –iSCSI targetStorage Area Network realization.
• PacketProtector – OpenWrt-based security distribution that includesIDS,IPS,VPN, and web antivirus capabilities. Packages included Snort, Snort-inline,FreeRADIUS,OpenVPN, DansGuardian andClamAV. 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.^[81]
• Qualcomm's QCA Software Development Kit (QSDK) which is being used as a development basis by manyOEMs is an OpenWrt derivative
• RutOS – an operating system for all Teltonika routers, based on OpenWrt. Source code found atGPL - Teltonika Networks Wiki.
• SmoothWAN – aggregation of multiple Internet connections and network conditioning usingSpeedify, Engarde and tinyfecvpn.
• Turris Omnia and Turris MOX routers run on an OpenWrt derivative
• Ubiquiti's wireless router firmwares are based on OpenWrt
• Diversegrassroots projects forwireless community networks, includingFreifunk, Libre-Mesh and qMp
• SomeTP-Link,Xiaomi,ZyXEL andD-Link router firmwares are derived from OpenWrt^[82][83]
• FreeWRT was a Linux distribution that was used in embedded systems such as WLAN devices from Linksys and Asus. Not related to a project (with same name) based on Sveasoft firmware.^{[citation needed]}
• Friendly Electronics manufactures the NanoPi series of SoC devices and makes available an OpenWRT derivative OS called FriendlyWRT.^[84]
• Ansuel's Technicolor Custom GUI a modified management web interface developed on the basis of the official Technicolor for Homeware firmware, which runs a fork of OpenWrt, unlocking Technicolor Modem/Routers.^[85]

• List of router firmware projects
• Prpl Foundation
• Banana Pi

• OpenWrt Firmware Selector
• OpenWrt Downloads
• OpenWrt Sysupgrade Server
• OpenWrt onGitHub
• OpenWrt Mailing Lists
• OpenWrt Forum
• LuCI project
• OpenWrt Summit &Wireless Battle Mesh
• GPL Code Center at Linksys