*BSD News Article 88862


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From: jimd@slip106.termserv.siu.edu (Jim Dutton)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: [Q] POP: virtual clients?
Date: Sun, 02 Feb 1997 20:50:31 CST
Organization: Southern Illinois University
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Comment: AmigaNOS v2.9p
In-Reply-To: <5cudt2$4qr@news.wco.com>
	     (from Jesse Monroy <jmonroy@wco.com>)
	     (at 1 Feb 1997 03:39:14 GMT)
Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:35304

Hi Jesse, on Feb 1 you wrote:

> : Jesse Monroy (jmonroy@wco.com) wrote:
> : : I'm checking to see if any of the packages for FreeBSD can have
> : : virtual clients. By this I mean, NOT virtual email domains, but
> : : users that can collect their email (with a pop3 client) and not
> : : have a login account on the machine.
> : : 
> mcurry@fred.net wrote:
> : Why don't you make the login accounts, but disallow shell access?
> :
> 	This has already been suggested and it is not
> 	an acceptable solution.

SOMEwhere along the line, there has to be some kind of userid/password
authentication done. By default, the /etc/passwd database is used. One
alternative would be to implement Kerberos and a "Kerborized" POP3 daemon
AND "kerborized" Sendmail. A properly installed setup could then allow for
user usage of a host running a POP3 server without them necessarily having
an entry in /etc/passwd.

You would need (probably) source code to the POP3 server and insert a couple
of lines where the "normal" userid/password checking takes place, to try
again (when the "normal" process fails) using a specific Kerberos security
server (and attendent database). The default Sendmail would also have to be
modified. This could be a LOT of work for JUST POP3, and/or a small number of
users.

There may be commercial mail system package which include POP3 support, and
has its own, independent authentication system which bypasses the need for
a (server) host userid.

If none of the above are cost effective, then the "create a user with a
null shell and no home directory" method may be what is needed.

Remember that POP3 is just one half of the mail transaction, and both halves
are going to require user authentication, somehow. Also, Sendmail and POP3
will need to run as the specified user to create the /var/mail/<user> file
(ie; the "mailbox") and process it.