  We propose a new extension of the Standard Model by a $U(1)_{B-L}$ gauge
symmetry in which the anomalies are canceled by two right-handed neutrinos plus
four chiral fermions with fractional B-L charges. Two scalar fields that break
the B-L symmetry and give masses to the new fermions are also required. After
symmetry breaking, two neutrinos acquire Majorana masses via the seesaw
mechanism leaving a massless neutrino in the spectrum. Additionally, the other
new fermions arrange themselves into two Dirac particles, both of which are
automatically stable and contribute to the observed dark matter density. This
model thus realizes in a natural way, without ad hoc discrete symmetries, a
two-component dark matter scenario. We analyze in some detail the dark matter
phenomenology of this model. The dependence of the relic densities with the
parameters of the model is illustrated and the regions consistent with the
observed dark matter abundance are identified. Finally, we impose the current
limits from LHC and direct detection experiments, and show that the high mass
region of this model remains unconstrained.
