* Instale o pacote para as chaves GPG
# apt-get install debian-archive-keyring
* Insira os repositórios no source.list
# vi /etc/apt/source.list
deb http://ftp.us.debian.org/debian/ testing main contrib non-free
deb-src http://ftp.us.debian.org/debian/ testing main contrib non-free
deb http://security.debian.org/ testing/updates main contrib non-free
deb-src http://security.debian.org/ testing/updates main contrib non-free
deb http://ftp.us.debian.org/debian/ testing-proposed-updates main contrib non-free