fli4l (flexible internet router for linux; previously: floppy isdn for linux) is a Linux distribution, actively developed by German developers since 2000. The projects main task is to provide a small Linux system that turns almost every machine into a router. The distribution can run from a floppy disk and was created with the aim of simple configuration and support for older hardware.[4][5][6]
fli4l can route between Ethernet and ISDN, DSL or UMTS, or just between Ethernet networks.[5]
Characteristics and requirements
fli4l is based on the Linux kernel. As the documentation is very extensive no knowledge of Linux is required, however a basic knowledge of network technology is needed.[7]
Newer versions of fli4l provide also the possibility to create a working installation on a CF card in a card reader, which card then in turn can operate from a CF adapter in an IDE slot. Also the generation of an ISO image is supported to run from a CD-ROM as well as from DOC/DOM for Embedded systems.[8]
fli4l can be configured on Linux, Unix and Windows systems using just text files.[9]
In addition, fli4l has the possibility to encrypt connections over the Internet or via Wireless LAN using OpenVPN or PPTP (Poptop).[10]
Versions
There are two development branches for fli4l, a stable and a development version.
The present stable release[2] is based on a Linux 3.16 kernel and supports virtualization by means of Xen and KVM. USB and Wireless LAN are supported to a great extent as well as current embedded hardware as APU, ALIX, Soekris, and EPIA series.
The 4.0 development version[3] also provides a Linux 4.1 kernel. Furthermore, it implements a new management and configuration layer for connections (so-called circuits) which has been designed from the ground up. It allows to use multiple WAN links (e.g. via DSL, ISDN, or UMTS) in parallel.
Optional packages
fli4l is a modular system using so-called OPT-packages. To create an individual configuration, only software packages for those options, that are needed, are downloaded and unzipped into the directory tree. To extend the basic functionality, a wide range of applications is available in the so-called OPT-database;[11] for example, optional packages can be used for monitoring traffic or an fli4l can function as a printserver. This process easily allows own developments, that can be made available to other users via the OPT-database.[11]
Device control
An fli4l router can be controlled and monitored with a browser-based interface. Besides, the program imonc (isdn monitor client) is available for Windows and Linux (GTK). imonc allows extensive control as well as remote-controlled update of the router's software.[12]