STFW

Avec une bête recherche sur pam_pwdb et debian on obtient notamment une page Debian-PAM-MiniPolicy :
http://www.golden-gryphon.com/cgi-bin/archzoom.cgi/srivasta@debian.(...)

Et cette page dit notamment :

Under no circumstances should any program in Debian use the pam_pwdb.so
module by default. Instead the pam_unix.so module should be used. Most
programs with RedHat support/default files will reference pam_pwdb.so in
their example files. Do not use this. There are several problems with
regard to pam_pwdb.so:

1) It attempts to reimplement glibc's NSS code. For example, if your
program uses pam_pwdb.so, and the user changes /etc/nsswitch.conf to use
NIS, NIS+, or LDAP, then your program will fail to work unless the user
also knows to edit /etc/pwdb.conf (which is not necessary for
pam_unix.so). In the case of LDAP, the program would become absolutely
useless until the user modifies the pam.d file themselves to use
pam_unix.so.

2) It adds to the layer of glibc function calls making it harder to
debug problems. Because libpwdb masks glibc native calls, it requires
being able to debug libpwdb, libpam, libc and the offending program.

Note that pam_unix.so takes the same module arguments as pam_pwdb.so, so
you can just replace the references. If you are not sure if the pam.d
files is correctly setup, please feel free to email it to me, and I will
glance it over.

UPDATE: libpwdb and this libpam-pwdb have been removed from Debian as of
Woody. So even if you decided to use pam_pwdb, it will be broken, so HAHA
:)

HTH.