Can I configure Ubuntu to never install a specific package even if it is required by another package I install?
To block the installation of a given package we may put the following lines in
Package: <nameofpackage> Pin: origin "" Pin-Priority: -1
By giving a negative priority for this pin we will block the installation of
<nameofpackage> from not further specified origin, i.e. our local repository. Of course we can use apt-pinning to pin a certain package version or specific origin.
Before you proceed it is strongly recommended to read the documentation given above and the manpage from apt_preferences because errors in these files are not checked by apt and if they occur may break your package management.
For an alternative, and to prevent updating of a given package see: