[SLUG] Seeking User & Group Management Advice

[Peter Rundle <prundle@xxxxxxxxxxxxxx>]

Sluggers,

I'm looking for some advice in regards to user and group account management.

I have a piece of software (Matlab) for which we have a single user 
licence. I.e the licence is tied to a user account on the Linux server. 
In order to use this software you have to "login" as that user. Or login 
as yourself and "su - matlab".

What is going to be the most elegant method for allowing users to run 
this software (one at a time) and save their results back to their home 
directory without being able to trash each others account?  Is there an 
elegant way to become another user but retain your group privledge?  
Perhaps something like login as peter then "su - matlab ; newgrp 
peter"?  When I do this it prompts for a "group" password, where is this 
kept and how do I set it?  (man newgrp tells me about the passwd but not 
how to set it). Ideally this would all be done in a "script" so the user 
clicks on the "matlab" icon on their icewm desktop (served via ltsp or 
vnc) and then they key in a passwd or two and volia matlab runs but they 
retain the ability to open/save work in their home directory.

Does anyone know of an open source matlab alternate?

The Linux server will provide, *nix logins, Imap e-mail, possibly some 
protected web pages with Apache, and samba shares of their home 
directory to their desktop PC. I've been considering using LDAP but on 
past experience found it to be quite a lot to chew, there will only be 
about 40 users.....Any opinions on whether LDAP is worth the effort. I 
would need users to be able to set their passwords and have that ripple 
through to each service. Currently PC's are just in a work group, trying 
to decide whether to use Samba as a domain controller/active directory?  
(I am not a windows domain/AD expert nor do I much care to become one).

TIA's

Pete.