Il se trouve toujours sous /etc/apt/sources.list Doit être édité en root.

Exemple de sources.list pour SID :

# stable
deb http://ftp.fr.debian.org/debian/ stable main contrib non-free
#deb-src http://ftp.fr.debian.org/debian/ stable main contrib non-free

# stable security
deb http://security.debian.org/ stable/updates main contrib non-free
#deb-src http://security.debian.org/ stable/updates main contrib non-free

# stable volatile
deb http://ftp.fr.debian.org/debian/ wheezy-updates main non-free contrib
#deb-src http://ftp.fr.debian.org/debian/ wheezy-updates main non-free contrib


# testing
deb http://ftp.fr.debian.org/debian/ testing main contrib non-free
#deb-src http://ftp.fr.debian.org/debian/ testing main contrib non-free

# testing security
deb http://security.debian.org/ testing/updates main contrib non-free
#deb-src http://security.debian.org/ testing/updates main contrib non-free


# sid
deb http://ftp.fr.debian.org/debian/ sid main contrib non-free
#deb-src http://ftp.fr.debian.org/debian/ sid main contrib non-free

Attention à bien regarder s'il faut remplacer les noms de certaines distribution !

Source

Ci-dessous mon sources.list pour Wheezy. On remarquera que je suis en Suisse…

# 

# deb cdrom:[Debian GNU/Linux 7 _Wheezy_ - Official Snapshot amd64 LIVE/INSTALL Binary 20130822-16:02]/ wheezy main

deb http://ftp.ch.debian.org/debian/ wheezy main contrib non-free
deb-src http://ftp.ch.debian.org/debian/ wheezy main contrib non-free

deb http://security.debian.org/ wheezy/updates main contrib non-free
deb-src http://security.debian.org/ wheezy/updates main contrib non-free

# wheezy-updates, previously known as 'volatile'
deb http://ftp.ch.debian.org/debian/ wheezy-updates main contrib non-free
deb-src http://ftp.ch.debian.org/debian/ wheezy-updates main contrib non-free

# backports
deb http://ftp.ch.debian.org/debian wheezy-backports main contrib non-free

# mozilla
deb http://mozilla.debian.net/ wheezy-backports iceweasel-aurora


#owncloud-client
deb http://download.opensuse.org/repositories/isv:ownCloud:devel/Debian_7.0/ /