In addition to the main repository, Debian also provides a contrib and a non-free repositories. These are note set up during the installation, mainly because of licensing reasons, but they can be added at any time:

To make future installation easier, the contrib and non-free repositories should be added to the list of available repositories. And because we will not compile packages from the sources, these references (deb-src) can be deactivated (commented):

The list of available repositories is stored in the configuration file /etc/apt/sources.list:

/etc/apt/sources.list

#
# deb cdrom:[Debian GNU/Linux 7.0.0 _Wheezy_ - Official Multi-architecture amd64/i386 NETINST #1 20130504-14:25]/ wheezy main
#deb cdrom:[Debian GNU/Linux 7.0.0 _Wheezy_ - Official Multi-architecture amd64/i386 NETINST #1 20130504-14:25]/ wheezy main

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

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

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

Update the local package database with the new sources:

root@server:~# aptitude update
Hit http://security.debian.org wheezy/updates Release.gpg
Hit http://security.debian.org wheezy/updates Release
Hit http://security.debian.org wheezy/updates/main i386 Packages
Get: 1 http://security.debian.org wheezy/updates/contrib i386 Packages [14 B]
Get: 2 http://security.debian.org wheezy/updates/non-free i386 Packages [14 B]
Get: 3 http://security.debian.org wheezy/updates/contrib Translation-en [14 B]
Hit http://security.debian.org wheezy/updates/main Translation-en
Get: 4 http://security.debian.org wheezy/updates/non-free Translation-en [14 B]
Hit http://ftp.pt.debian.org wheezy Release.gpg
Hit http://ftp.pt.debian.org wheezy-updates Release.gpg
Hit http://ftp.pt.debian.org wheezy Release
Hit http://ftp.pt.debian.org wheezy-updates Release
Hit http://ftp.pt.debian.org wheezy/main i386 Packages
Get: 5 http://ftp.pt.debian.org wheezy/contrib i386 Packages [42.3 kB]
Get: 6 http://ftp.pt.debian.org wheezy/non-free i386 Packages [77.5 kB]
Get: 7 http://ftp.pt.debian.org wheezy/contrib Translation-en [34.8 kB]
Hit http://ftp.pt.debian.org wheezy/main Translation-en
Get: 8 http://ftp.pt.debian.org wheezy/non-free Translation-en [66.1 kB]
Hit http://ftp.pt.debian.org wheezy-updates/main i386 Packages
Get: 9 http://ftp.pt.debian.org wheezy-updates/contrib i386 Packages [14 B]
Get: 10 http://ftp.pt.debian.org wheezy-updates/non-free i386 Packages [14 B]
Get: 11 http://ftp.pt.debian.org wheezy-updates/contrib Translation-en [14 B]
Hit http://ftp.pt.debian.org wheezy-updates/main Translation-en
Get: 12 http://ftp.pt.debian.org wheezy-updates/non-free Translation-en [14 B]
Fetched 221 kB in 6s (36.1 kB/s)

Current status: 664 new [+664].

In some cases, Internet must pass through proxy. apt and aptitude can be configured to use a proxy in two ways:

• Temporarily, by setting an environment variable http_proxy or ftp_poxy with the proxy's URL:

root@server:~# export http_proxy="http://proxy.example.com:3128/"

O aptitude terá em conta esta variável quando se ligar à Internet.

• Permanently, by changing the apt configuration in the /etc/apt/apt.conf configuration file:

/etc/apt/apt.conf

Acquire::http::Proxy "http://proxy.example.com:3128/";

The syntacx of the http_proxy is “http://[[user][:pass]@]xxx.xxx.xxx.xxx[:port]/”, where:

• user:pass : username and password, in case proxy needs authentication and/or authorization;
• xxx.xxx.xxx.xxx : the address of the proxy server;
• port : the proxy's port number;

• Debian.org: Packages (http://www.debian.org/distrib/packages)
• Debian worldwide mirror sites (http://www.debian.org/mirror/list)