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From: rickert@mp.cs.niu.edu (Neil Rickert)
Newsgroups: comp.mail.misc
Subject: Re: Problem with mail aliases
Message-ID: <1990Nov16.144919.13837@mp.cs.niu.edu>
Date: 16 Nov 90 14:49:19 GMT
References: <68488@bu.edu.bu.edu> <1990Nov15.032104.15003@onion.pdx.com>
Distribution: usa
Organization: Northern Illinois University
Lines: 31

In article <1990Nov15.032104.15003@onion.pdx.com> jeff@onion.pdx.com (Jeff Beadles) writes:
>Try this, it tastes great AND is less filling. :-)
>
>listserv:	/usr/guest/ermis/requests
>
>Sendmail will automatically append to the file for you.  Just create it, and
>make sure that everyone can access it.  (Both for read and write)  Yes kiddies,
>this is yash (Yet another "security" hole.  If anyone can read/write to the
>file, then they can also change the contents...)
>
 In recent versions of sendmail (certainly 5.64) there is an alternative.
According to the code comments, you can set the suid and/or sgid bits on the
file.  In this case sendmail will write with the permissions of the owner
and/or group.  Note that you have to be careful NOT to set any 'x' bits,
or sendmail will refuse to write.  It seemed to work in my tests.  I don't
know when this first became part of sendmail.  But it does allow you to set
up a file so that sendmail can write to it, yet still restrict who else may
read or write.

 A warning, however.  Sendmail does not seem to use any file locking when
mailing to a file.  Unless the volume of mail to this alias is high,
that is perhaps not a problem, for conflicts are improbable.  If you want to
totally avoid the problem of two messages being written concurrently, and
partially destroying each other, you can always create a new user loginid for
the system, and use that user's mailbox as the file.

-- 
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  Neil W. Rickert, Computer Science               <rickert@cs.niu.edu>
  Northern Illinois Univ.
  DeKalb, IL 60115.                                  +1-815-753-6940