With dselect the Accept menu option is used to declare the location of the archives. apt-get obtains this information from the configuration file /etc/apt/sources.list. When the system installation has been completed from CDROM this file will contain lines like:
deb cdrom:[<disk label>]/ unstable contrib main
for each of the CDs that were registered during the installation process. While this may be adequate for all you future needs, apt-get can also access archives over the Internet. While your CDs will never change, the FTP archives are always being updated. Even the stable release will be updated with packages that need security fixes, and other serious bugs.
Depending upon how much risk you are willing to take, you can even follow the latest ``unstable'' packages using apt-get, providing the latest packages being produced by the Debian developers. However, immediately following the release of a new ``stable'' version of Debian, the unstable release tends to be very unstable and is not suitable for the average user. If you choose to take this risk, be advised that this could result in the installation of a broken package that is critical to your system function, making your system unusable.
In addition to the stable and unstable labels, each release has a code name that does not change as the release progresses from unstable thru frozen to the stable release. Dwarf recommends that you track stable, by tracking the named release. For the 2.2 release of Debian this name is potato. The 2.3 release is named woody. Tracking potato, instead of unstable, keeps your system stable, even after the new release and gives you the choice of when to upgrade to the new release.
In order to set up apt-get to use FTP to retrieve packages from an archive on the net, first comment out the cdrom: lines. (Comments are formed by placing a # as the first character in the line.) Then add the following line:
deb ftp://ftp.debian.org/debian potato main contrib
The ftp://ftp.debian.org/debian term names the archives site on the Internet. There are many Debian mirrors available throughout the world. Each mirror will report alternative sites when you log in using an FTP client. Choose one that is ``close'' to you on the Internet.
The potato term identifies the release to use within the archives, and the remaining terms indicate which sections of the archives apt-get will search for packages. For those people who reside inside the United States, several important packages are not available from US servers because of cryptographic laws there. These packages can be legally obtained by US citizens from servers outside the US, so if you want access to these packages you will need to add another line specifying that server and the section you wish to access.