The Penguin Liberation Front (PLF) is a project to provide packages of so-called "endangered software" - free software

Free software

Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...

 which may not be legally distributable in some countries - for Linux

Linux

Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

 users and developers. This software cannot be included in Linux distribution

Linux distribution

A Linux distribution is a member of the family of Unix-like operating systems built on top of the Linux kernel. Such distributions are operating systems including a large collection of software applications such as word processors, spreadsheets, media players, and database applications...

s for various reasons, such as:

• Software patent
  Software patent
  Software patent does not have a universally accepted definition. One definition suggested by the Foundation for a Free Information Infrastructure is that a software patent is a "patent on any performance of a computer realised by means of a computer program".In 2005, the European Patent Office...
  
  s, prohibiting the use of abstract algorithms regardless of implementation
• Other intellectual property
  Intellectual property
  Intellectual property is a term referring to a number of distinct types of creations of the mind for which a set of exclusive rights are recognized—and the corresponding fields of law...
  
   laws, such as DMCA in the United States
  United States
  The United States of America is a federal constitutional republic comprising fifty states and a federal district...
  
  , and EUCD in the European Union
  European Union
  The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
  
  
• Security laws, such as strong cryptography prohibition in many countries

Much free software is affected by these issues, and is therefore illegal in some parts of the world. This makes use of these packages difficult even for those in countries where no such laws are broken, since these packages are generally not carried in standard package repositories.

The PLF focused on Mandriva Linux

Mandriva Linux

Mandriva Linux is a Linux distribution distributed by Mandriva. It uses the RPM Package Manager...

 and used urpmi

Urpmi

urpmi is a Mandriva Linux package management tool for installing, removing, updating and querying software packages of local or remote media. It wraps around the package manager rpm with the aim that the user should not have to suffer the often-encountered dependency hell...

 for distribution. An effort to provide packages for Ubuntu

Ubuntu (operating system)

Ubuntu is a computer operating system based on the Debian Linux distribution and distributed as free and open source software. It is named after the Southern African philosophy of Ubuntu...

 was started, but later shut down due to lack of time to maintain it. A free packages repository for Ubuntu similar to PLF is instead maintained by the Medibuntu

Medibuntu

Medibuntu is a community-maintained repository of Debian packages that cannot be included into the Ubuntu distribution for legal reasons....

project.