  We present a detailed X-ray spectral analysis of the sources in the 1Ms
catalog of the Chandra Deep Field South (CDFS) taking advantage of optical
spectroscopy and photometric redshifts for 321 sources. As a default spectral
model, we adopt a power law with slope Gamma with an intrinsic redshifted
absorption N_H, a fixed Galactic absorption and an unresolved Fe emission line.
For 82 X-ray bright sources, we perform the X-ray spectral analysis leaving
both Gamma and N_H free. The weighted mean value is <Gamma>~ 1.75+-0.02, with
an intrinsic dispersion of sigma~0.30. We do not find hints of a correlation
between Gamma and the N_H. We detect the presence of a scattered component at
soft energies in 8 sources, and a pure reflection spectrum, typical of
Compton-thick AGN, in 14 sources (Compton-thick AGN candidates). The intrinsic
N_H distribution shows a lognormal shape, peaking around log(N_H)~23.1 and with
sigma~1.1. We find that the fraction of absorbed sources (with N_H>10^{22}
cm^{-2}) in the sample is constant (at the level of about 75%) or moderately
increasing with redshift. Finally, we compare the optical classification to the
X-ray spectral properties, confirming that the correspondence of unabsorbed
(absorbed) X-ray sources to optical Type I (Type II) AGN is accurate for at
least 80% of the sources with spectral identification (1/3 of the total X-ray
sample).
