Se um dos objectivos do Debian é a estabilidade, o seu preço é a utilização de software bastante testado e, portanto, antigo. No entanto, pode surgir necessidade de instalar software mais recente o inexistente à data de saída do debian Lenny. Para isso existe o repositório backports, que disponibiliza versões mais recentes ou inexistente à data de lançamento do Lenny.

A localização do repositório deve ser adicionada à lista existente em /etc/apt/sources.list:

# [...]

# debian-backports
deb http://www.backports.org/debian lenny-backports main contrib non-free

# [...]

A chave pública do repositório backports também deve ser adicionada à lista de chaves conhecidas pelo apt:

server:~# aptitude install debian-backports-keyring
Reading package lists... Done
Building dependency tree
Reading state information... Done
Reading extended state information
Initializing package states... Done
Reading task descriptions... Done
The following NEW packages will be installed:
  debian-backports-keyring
0 packages upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 3362B of archives. After unpacking 49.2kB will be used.
WARNING: untrusted versions of the following packages will be installed!

Untrusted packages could compromise your system's security.
You should only proceed with the installation if you are certain that
this is what you want to do.

  debian-backports-keyring

Do you want to ignore this warning and proceed anyway?
To continue, enter "Yes"; to abort, enter "No": Yes
Writing extended state information... Done
Get:1 http://www.backports.org lenny-backports/main debian-backports-keyring 2009.02.20 [3362B]
Fetched 3362B in 0s (11.4kB/s)
Selecting previously deselected package debian-backports-keyring.
(Reading database ... 35721 files and directories currently installed.)
Unpacking debian-backports-keyring (from .../debian-backports-keyring_2009.02.20_all.deb) ...
Setting up debian-backports-keyring (2009.02.20) ...
OK
Reading package lists... Done
Building dependency tree
Reading state information... Done
Reading extended state information
Initializing package states... Done
Writing extended state information... Done
Reading task descriptions... Done

É possível listar as chaves utilizadas pelo apt:

server:~# apt-key list
/etc/apt/trusted.gpg
--------------------
pub   1024D/6070D3A1 2006-11-20 [expires: 2009-07-01]
uid                  Debian Archive Automatic Signing Key (4.0/etch) <ftpmaster@debian.org>

pub   1024D/ADB11277 2006-09-17
uid                  Etch Stable Release Key <debian-release@lists.debian.org>

pub   1024D/BBE55AB3 2007-03-31 [expires: 2010-03-30]
uid                  Debian-Volatile Archive Automatic Signing Key (4.0/etch)
sub   2048g/36CA98F3 2007-03-31 [expires: 2010-03-30]

pub   1024D/F42584E6 2008-04-06 [expires: 2012-05-15]
uid                  Lenny Stable Release Key <debian-release@lists.debian.org>

pub   4096R/55BE302B 2009-01-27 [expires: 2012-12-31]
uid                  Debian Archive Automatic Signing Key (5.0/lenny) <ftpmaster@debian.org>

pub   2048R/6D849617 2009-01-24 [expires: 2013-01-23]
uid                  Debian-Volatile Archive Automatic Signing Key (5.0/lenny)

pub   1024D/16BA136C 2005-08-21
uid                  Backports.org Archive Key <ftp-master@backports.org>
sub   2048g/5B82CECE 2005-08-21

O repositório está pronto a ser utilizado, com a sequência habitual aptitude update, seguido de aptitude install <nome_do_pacote>.

• Debian Backports (*http://www.backports.org)