  We analyze the propagation of open and unoriented strings on the
Neveu-Schwarz pentabrane (N5-brane) along the lines of a similar analysis for
the SU(2) WZNW models. We discuss the two classes of open descendants of the
diagonal models and a series of Z_2 projected models which exist only for even
values of the level k and correspond to branes at D-type orbifold
singularities. The resulting configurations of branes and planes are T-dual to
those relevant to the study of dualities in super Yang-Mills theories. The
association of Chan-Paton factors to D-brane multiplicities is possible in the
semi-classical limit k -> infinity, but due to strong curvature effects is
unclear for finite k. We show that the introduction of a magnetic field implies
a twist of the SU(2) current algebra in the open-string sector leading to
spacetime supersymmetry breaking.
