OpenWrt (from ''open wireless router'') is an open-source project for embedded operating systems based on

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which i ...

, primarily used on embedded devices to route network traffic. The main components are Linux, util-linux, musl, and BusyBox. All components have been optimized to be small enough to fit 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 8000 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,

smartphone A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whic ...

s, pocket computers (e.g. Ben NanoNote). It is also possible to run OpenWrt on

personal computer A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tech ...

s and laptops.

History

The OpenWrt project was started in 2004 after Linksys had built the

firmware In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide ...

for their WRT54G series of wireless routers with code licensed under the

GNU General Public License The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end user In product development, an end user (sometimes end-user) is a person who ultimately uses or is intended to ulti ...

. Under the terms of that license, Linksys was required to make the source code of its modified version available under the same license, 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 a Linux 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 the b43 kernel module) WLAN for many

Broadcom Broadcom Inc. is an American designer, developer, manufacturer and global supplier of a wide range of semiconductor and infrastructure software products. Broadcom's product offerings serve the data center, networking, software, broadband, wirel ...

-based routers could only be had via the proprietary wl.o module (and which required Linux 2.4.x). OpenWrt releases were historically named after cocktails, such as White Russian, Kamikaze, Backfire, Attitude Adjustment, Barrier Breaker and Chaos Calmer, and their recipes were included in the message of the day (motd) displayed after logging in using the command-line interface. In May 2016, OpenWrt was forked by a group of core OpenWrt contributors due to disagreements on internal process. The fork was dubbed Linux Embedded Development Environment (LEDE). The schism was reconciled a year later. Following the remerger, announced in January 2018, 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. "

Releases

LEDE

The Linux Embedded Development Environment (LEDE) project was a fork of the OpenWrt project and shared many of the same goals. It was created in May 2016 by a group of core OpenWrt contributors due to disagreements on OpenWrt internal processes. The schism was nominally reconciled a year later in May 2017 pending approval of the LEDE developers. 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, and formally announced in January 2018. The merging process was completed before the OpenWrt 18.06 release.

Features

OpenWrt features a writeable

root file system In a computer file system, and primarily used in the Unix and Unix-like operating systems, the root directory is the first or top-most directory in a hierarchy. It can be likened to the trunk of a tree, as the starting point where all branche ...

, 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 compressed SquashFS file system with a writeable JFFS2 file system using overlayfs. Additional software can be installed with the ''opkg'' package manager and the package repository contains approximately 8000 packages (by 2022). OpenWrt can be configured through either a command-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. Additional web interfaces, such as Gargoyle, 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, like IPv4,

IPv6 Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet. I ...

DNS The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names assigned to ...

, DHCP, routing, firewall,

NAT Nat or NAT may refer to: Computing * Network address translation (NAT), in computer networking Organizations * National Actors Theatre, New York City, U.S. * National AIDS trust, a British charity * National Archives of Thailand * National ...

, port forwarding and

WPA WPA may refer to: Computing *Wi-Fi Protected Access, a wireless encryption standard *Windows Product Activation, in Microsoft software licensing *Wireless Public Alerting (Alert Ready), emergency alerts over LTE in Canada * Windows Performance Ana ...

. Other features include: * Extensible configuration of the entire hardware drivers, e.g. built-in network switches and their VLAN-capabilities, WNICs, DSL modems, FX, available hardware buttons, etc. * Mesh networking through

B.A.T.M.A.N. The Better Approach to Mobile Ad-hoc Networking (B.A.T.M.A.N.) is a routing protocol for Multi-hop routing, multi-hop mobile ad hoc networks which is under development by the German "Freifunk" community and intended to replace the Optimized Link ...

, OLSR and

IEEE 802.11s IEEE 802.11s is a wireless local area network (WLAN) standard and an IEEE 802.11 amendment for mesh networking, defining how wireless devices can interconnect to create a wireless LAN mesh network, which may be used for relatively fixed (not mobile) ...

-capabilities of the WNIC drivers and other ad hoc mesh routing protocols that have been implemented within Linux. * Wireless functionality, e.g. make the device act as a

wireless repeater A wireless repeater (also called wireless range extender or wifi extender) is a device that takes an existing signal from a wireless router or wireless access point and rebroadcasts it to create a second network. When two or more hosts have to ...

, a wireless access point, a

wireless bridge A network bridge is a computer networking device that creates a single, aggregate network from multiple communication networks or network segments. This function is called network bridging. Bridging is distinct from routing. Routing allows m ...

, a captive portal, or a combination of these with e.g. ChilliSpot,

WiFiDog Captive Portal WiFiDog was an open source embeddable captive portal solution used to build wireless hotspots. It is no longer an active project after not being updated for several years. WiFiDog consists of two components: the ''gateway'' and the ''authenticatio ...

, etc. * Wireless security: Packet injection, e.g
Airpwn

lorcon lorcon (acronym for ''Loss Of Radio CONnectivity'') is an open source network tool. It is a library for injecting 802.11 (WLAN) frames, capable of injecting via multiple driver frameworks, without the need to change the application code. Lorcon is ...

, e.a. * Dynamically-configured port forwarding protocols

UPnP Universal Plug and Play (UPnP) is a set of networking protocols that permits networked devices, such as personal computers, printers, Internet gateways, Wi-Fi access points and mobile devices to seamlessly discover each other's presence on the n ...

and NAT-PMP through upnpd, etc. *

Port knocking In computer networking, port knocking is a method of externally opening ports on a firewall by generating a connection attempt on a set of prespecified closed ports. Once a correct sequence of connection attempts is received, the firewall rules a ...

* TR-069 (CWMP) client * IPS via

Snort Snort may refer to: * Nose-blowing * Sniffle * Nasal administration, the inhaling of drugs through the nose * Snort (software), a package for intrusion detection * Snort, a map-coloring game * Insufflation, the act of blowing, breathing, hissing, ...

* Active queue management (AQM) through the network scheduler of the Linux kernel, with many available queuing disciplines. CoDel has been backported to Kernel 3.3. This encapsulates Traffic shaping to ensure fair distribution of bandwidth among multiple users and quality of service (QoS) for simultaneous use of applications such as

VoIP Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Interne ...

, online gaming, and streaming media without experiencing the negative impacts of link saturation. * Load balancing for use with multiple ISPs using source-specific routing * IP tunneling ( GRE, OpenVPN, pseudowire, etc.) * Extensible realtime network monitoring and statistics through e.g. RRDtool, Collectd, Nagios, Munin lite, Zabbix, etc. * Dynamic DNS services to maintain a fixed domain name with an ISP that does not provide a static IP address * OpenWrt supports any hardware that has Linux support; devices that can be connected (e.g. over USB) include ** Printers ** Mobile broadband modems ** Webcams ** Sound cards * Notable software packages to use the hardware support are ** File sharing via SAMBA, (Windows-compatible), NFS, FTP, SFTP. Printer sharing over the print server CUPS (spooling) or

p910nd P91 may refer to: * , a patrol boat of the Royal Australian Navy * Papyrus 91, a biblical manuscript * Ruger P91, a pistol * P91, a List of national roads in Latvia#P91, state regional road in Latvia {{Disambiguation ...

(non-spooling) ** PulseAudio, Music Player Daemon, Audio/Video streaming via DLNA/ UPnP AV standards, iTunes ( DAAP) server ** Asterisk (PBX) ** MQ Telemetry Transport through Mosquitto

Development

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 A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is running. For example, a compiler that runs on a PC but generates code that runs on an Android smartphone is a cross ...

toolchain. 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. OpenWrt Buildroot provides the following features: * 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.

Hardware compatibility

OpenWrt runs many different routers and includes a table of compatible hardware on its website. In its buyer's guide, it notes that users recommend devices equipped with wireless chips from either Qualcomm's Atheros, Ralink (now MediaTek) or any vendor with open source drivers and specifications. OpenWrt also recommends choosing a device with a minimum of 16 MB of flash and 64 MB of RAM, preferably higher amounts.

Adoption

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 power ISPs routers and gateways made by Prpl Foundation * SIMET Box, developed by NIC.br, is OpenWrt-based

Derivative projects

AREDN
The Amateur 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 of bufferbloat fixes * 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 on

GitHub GitHub, Inc. () is an Internet hosting service for software development and version control using Git. It provides the distributed version control of Git plus access control, bug tracking, software feature requests, task management, co ...

. * 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 for mesh 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 a
mkschreder/juci
and is still usable by installing openwrt feed found a
mkschreder/juci-openwrt-feed
*

libreCMC LibreCMC is a Linux-libre distribution for computers with minimal resources, such as the Ben NanoNote, ath9k-based Wi-Fi router A wireless router is a device that performs the functions of a router and also includes the functions of a wire ...

OpenWrt-based distribution which excludes non-free software or binary blobs, endorsed by the Free Software Foundation * 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.
OpenMPTCProuter
aggregation of multiple Internet connections using Multipath TCP * OpenSAN iSCSI target Storage Area Network realization. * PacketProtector OpenWrt-based security distribution that includes

IDS IDS may refer to: Computing * IBM Informix Dynamic Server, a relational database management system * Ideographic Description Sequence, describing a Unihan character as a combination of other characters * Integrated Data Store, one of the first da ...

, 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. * Qualcomm's QCA Software Development Kit (QSDK) which is being used as a development basis by many OEMs is an OpenWrt derivative * RutOS an operating system for all Teltonika routers, based on OpenWrt. Source code found a
GPL - Teltonika Networks Wiki
* Turris Omnia and Turris MOX routers run on an OpenWrt derivative * Ubiquiti's wireless router firmwares are based on OpenWrt * Diverse grassroots projects for wireless community networks, including Freifunk, Libre-Mesh and qMp * Some TP-Link, Xiaomi, ZyXEL and D-Link router firmwares are derived from OpenWrt * 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. * Friendly Electronics manufactures the NanoPi series of SoC devices and makes available an OpenWRT derivative OS called FriendlyWRT. * 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.