  We study the dc conductance and current fluctuations in diffusive voltage
biased SNS junctions with a tunnel barrier inside the mesoscopic normal region.
We find that at subgap voltages, eV<2Delta/n, the current associated with the
chain of n Andreev reflections is mapped onto the quasiparticle flow through a
structure of n+1 voltage biased barriers connected by diffusive conductors. As
a result, the current-voltage characteristic of a long SNINS structure obeys
Ohm's law, in spite of the complex multiparticle transport process. At the same
time, nonequilibrium heating of subgap electrons produces giant shot noise with
pronounced subharmonic gap structure which corresponds to stepwise growth of
the effective transferred charge. At eV\to 0, the shot noise approaches the
magnitude of the Johnson-Nyquist noise with the effective temperature
T^*=Delta/3, and the effective charge increases as (e/3)(1 + 2Delta/eV), with
the universal ``one third suppression'' factor. We analyse the role of
inelastic scattering and present a criterion of strong nonequilibrium.
