  We present a simulation method to study electrolyte solutions in a dielectric
slab geometry using a modified 3D Ewald summation. The method is fast and easy
to implement, allowing us to rapidly resum an infinite series of image charges.
In the weak coupling limit, we also develop a mean-field theory which allows us
to predict the ionic distribution between the dielectric charged plates. The
agreement between both approaches, theoretical and simulational, is very good,
validating both methods. Examples of ionic density profiles in the strong
electrostatic coupling limit are also presented. Finally, we explore the
confinement of charge asymmetric electrolytes between neutral surfaces.
