We focus on the confinement of two-dimensional Dirac fermions
within the waveguides created by realistic magnetic fields. Understanding of
their band structure is of our main concern. We provide easily applicable
criteria that can guarantee existence or absence of the energy bands and,
this way, provide a valuable insight into the systems where analytical
solution is impossible. The general results are employed in specific systems
where the waveguide is created by the magnetic field of a set of electric
wires or by a magnetized strip.