  The exact nonperturbative confining solutions of the SU(3)-Yang-Mills
equations recently obtained by author in Minkowski spacetime with the help of
the black hole theory techniques are analysed and on the basis of them the
gluon propagator corresponding to linear confinement at large distances (small
momenta) is constructed in a nonperturbative way. At small distances (large
momenta) the resulting propagator passes on to the standard (nonperturbative)
gluon propagator used in the perturbative quantum chromodynamics (QCD). The
results suggest some scenario of linear confinement for mesons and quarkonia
which is also outlined. As a consequence there arises a motivation for studying
the relativistic bound states in the above confining SU($N$)-Yang-Mills fields.
This possiblity is realized for $N=2,3,4$ with the aid of the black hole theory
results about spinor fields on black holes with a subsequent application to the
charmonium spectrum in the most important physical case N=3. Incidentally
uniqueness of the confining solutions is discussed and a comparison with the
nonrelativistic potential approach is given.
