acl ne peut pas être installé sur un serveur ubuntu

Les commandes setfacl/getfacl ne fonctionnent pas sur mon serveur, il est indiqué :

The program 'setfacl' is currently not installed. You can install it by typing:
sudo apt-get install acl

quand j'ai essayé de l'installer, il est dit :

sudo apt-get install acl

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package acl is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'acl' has no installation candidate