  In this work we present a common framework for neutrino mass and dark matter.
Specifically, we work with a local $\mathcal{B-L}$ extension of the standard
model which has three right-handed neutrinos, $n_{R_{i}}$, and some extra
scalars, $\Phi$, $\phi_{i}$ besides the standard model fields. The
$n_{R_{i}}$'s have non-standard $\mathcal{B-L}$ quantum numbers and thus these
couple to different scalars. This model has the attractive property that an
almost automatic $Z_2$ symmetry acting only on a fermionic field, $n_{R3}$, is
present. Taking advantage of this $Z_2$ symmetry, we study both the neutrino
mass generation via a natural see-saw mechanism in low energy and the
possibility of $n_{R3}$ to be a DM candidate. For this last purpose, we study
its relic abundance and its compatibility with the current direct detection
experiments.
