By adding new repositories give more power, more flexibility and access to software for Linux Debian.

First of all, we're going to get a copy of the file repository;

deathbian:~# cp /etc/apt/sources.list /etc/apt/sources.list_backup

Next, edit the file, we can use gedit, vi, nano etc;

deathbian:~# vim /etc/apt/sources.list

And add the following lines;

file: / etc / apt / sources.list 
  deb http://security.debian.org/ stable / updates main 
  deb-src http://security.debian.org/ stable / updates main 

  deb etch main ftp://ftp.us.debian.org/debian/ 
  deb-src ftp://ftp.us.debian.org/debian/ etch main

As we can see, the first two lines we add the repository of security for Debian Stable (now Etch), and the second block gives us the option to upgrade and install new software for Etch.
Clearly, there are also repositories for Lenny (testing) and Sid (unstable), which should not be added in a sources.list on the same server.

Note: The URLs of the repositories refer to machines located in USA. To improve the transfer is best to choose a mirror of your country.

We come to save the edited file, now you can update the list of packages, type;

deathbian:~# aptitude update
Note: You can also build your list of repositories to measure, using the tool netselect-apt, this tool gives us the option of choosing among multiple repositories available.

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