Nfs

bonjour a tous svp est ce que quelqu'un peut m'aider a installer nfs-kernel-server
j'ai essayer avec la commande apt get-install nfs-kernel-server mais ça ne marche pas et voila ce qui m'affiche
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package nfs-common 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: Unable to locate package nfs-kernel-server
E: Package 'nfs-common' has no installation candidate
E: Unable to locate package portmap
mrc