  We characterize the motion of charged as well as neutral tracers, in an
electrolyte embedded in a varying section channel. We exploit a set of
systematic approximations that allows us to simplify the problem, yet capturing
the essential of the interplay between the geometrical confinement provided by
the corrugated channel walls and the electrolyte properties. Our simplified
approach allows us to characterize the transport properties of corrugated
channels when a net flux of tracers is obtained by keeping the extrema of the
channel at different chemical potentials. For highly diluted tracer
suspensions, we have characterized tracers currents and we have estimated the
net electric current which occurs when both positively and negatively charged
tracers are considered.
