managing user accounts without NIS

[Victor Ortega]

I have looked at the archives searching for a good way to manage user
accounts on a beowulf cluster.  Some people suggested using rsync, but
my question is, how?  rsync is nothing more than an efficient version
of rcp; it doesn't really "synchronize" files--by that I mean that as
soon as (or soon after) one file gets modified, the other files get
updated.  In particular, I want my users to be able to change their
passwords or their login shells from any node and have the relevant
files in /etc updated on all nodes, without the users having to do
anything else on their part (like running some "update" script).  I
would really rather not write setuid-root wrappers to passwd and chsh,
as I don't want to inadvertently introduce a security hole to my
system.  I have considered writing a PAM module, but I don't think
this would cover the chsh case.  I also don't want to hack the kernel
or the file system to manage user accounts.  Any suggestions?

Victor