The OpenWrt project was started in 2004 after Linksys had built the firmware for their WRT54G series of wireless routers with code licensed under the GNU General Public License. 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-based routers could only be had via the proprietary wl.o module (and which required Linux 2.4.x).
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.
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. Merging process was completed before OpenWRT 18.06 release.
OpenWrt features a writeable root 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 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 6000 packages.
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'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-compilationtoolchain.
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.)
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.
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 or Ralink (now MediaTek). OpenWrt also recommends choosing a device with a minimum of 16 MB of flash and 64 MB of RAM, preferably higher amounts.
OpenWrt, especially its Buildroot build system, has been adopted as structure for other efforts. For example
AltiWi "one-time-fee-only" replacement for Cloudtrax.
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.
Qualcomm's QCA Software Development Kit (QSDK) which is being used as a development basis by many OEMs is an OpenWrt derivative
Turris Omnia and Turris MOX routers run on an OpenWrt derivative
Ubiquiti's wireless router firmwares are based on OpenWrt
^"Welcome to the OpenWrt Project (OpenWrt Project)". OpenWrt. January 2018. Retrieved 2018. As of January 2018, the current Stable OpenWrt release [17.01.4] was built from the LEDE 17.01 source code, and branded with the LEDE project name. Development versions of OpenWrt are currently branded with the OpenWrt name, and have a version number of 18.01 "