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From: Jim Dennis <jimd@mistery.mcafee.com>
Message-Id: <199605151750.KAA30078@mistery.mcafee.com>
Subject: Re: Setting up user accounts but with no email access
To: mrm@Mole.ORG (M.R.Murphy)
Date: Wed, 15 May 1996 10:50:12 -0700 (PDT)
Cc: terry@lambert.org, freebsd-questions@freebsd.org,
        paul@riker.comcirc.com.au
In-Reply-To: <199605151332.GAA24831@meerkat.mole.org> from "M.R.Murphy" at May 15, 96 06:32:55 am
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> 
> > > I am setting up a few user accounts on our WWW server so that users can
> > > FTP to the server to post up their web pages into their relevant 
> > > web page directories.
> > > 
> > > How can I disable email access for these users. ie. I dont want them
> > > to have an email account, only an account to FTP files to.
> >
> > The easiest (grossest) way would be to define another name for
> > the machine and *not* put in a Cw entry for it.
> [...]
> 
> Add the users to the password file as usual. Then put a different mailer
> program instead of P=/usr/libexec/mail.local for Mlocal in /etc/sendmail.cf.
> Do in your replacement program what you will. That replacement program
> can be a script. Try this first to see how it behaves:
> 
> #!/bin/sh
> echo $@ >>/tmp/mail.log
> exec /usr/libexec/mail.local $@
> 
> --
> Mike Murphy  mrm@Mole.ORG  +1 619 598 5874

	Yuck!

	This sounds like a whole bunch of security problems just 
	waiting to happen.  (At least double quote the "$@")!

	You might use procmail as your local delivery agent.
	In you /etc/passwd file define all of the non-mail users
	to have the same $HOME directory (i.e. "/export/home/.nomail/")
	In that directory create a file named ".procmailrc" (or a 
	suitable ".forward").

	The procmail recipe in that directory can bounce all mail
	with a custom nasty gram.

	Advantages of this approach:

			procmail is designed to work as a local delivery agent
			issues of file locking and a variety of security 
			considerations are already built-in.

			(don't just your shell or PERL code for security --
			 particularly when called via sendmail)

			procmail can be run non-suid and non-sgid (this approach
			doesn't *require* that procmail be installed in sendmail.cf
			as Mlocal).

	Disadvantages:

			I'm not sure of the exact requirements on ownership and
			permissions that this would require for the 
			"home" directory and the .procmailrc

			I haven't done this -- so I might find some problem
			during implementation that I haven't foreseen here.

Jim Dennis,
System Administrator,
McAfee Associates