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From: rickert@mp.cs.niu.edu (Neil Rickert)
Newsgroups: comp.mail.sendmail
Subject: Re: problem with uucp-originated mail
Message-ID: <1990Dec11.040246.11831@mp.cs.niu.edu>
Date: 11 Dec 90 04:02:46 GMT
References: <9812@darkstar.ucsc.edu> <1990Dec6.234758.28937@mp.cs.niu.edu> <198@touch.touch.com>
Organization: Northern Illinois University
Lines: 54

In article <198@touch.touch.com> kehres@touch.touch.com (Tim Kehres) writes:
>In article <1990Dec6.234758.28937@mp.cs.niu.edu> rickert@mp.cs.niu.edu (Neil Rickert) writes:
>:
>text regading how rmail looks for bang characters (!) to determine the remote
>machine name....
>
>>  Solutions:
>> 
>> 	Best solution - change the mac software to use 'host!user'
>> 	or even 'host.UUCP!user' rather than 'user@host.UUCP'
>
>I would have to strongly disagree with you here.  If a host is passing valid
>domain style addresses, then rmail should accept them.  Forcing old UUCP style
>addressing on a community simply because of a single broken piece of software
>in my opinion is not justified.
>
>My main disagreement here is not about the two options presented, only the
>classification of the above as the "best" solution.
>
 While I certainly don't object to changing rmail to accept domain style
addresses, and am using such an 'rmail' myself, there are reasons I suggested
changing the code on the Mac is the best approach:

	1.  Changing the mail format on the Mac to conform with UUCP standards
	    will make the MAC address acceptable if it starts talking UUCP
	    to other hosts.

	2.  Just changing 'rmail' to accept domain style addresses may not be
	    reliable.  You may also have to make it suid root, and change it
	    to do setuid(0) internally.  (This of course has security
	    implications).

	    The problem is that sendmail tries to prevent a user forging
	    another user's mail.  It will only accept a specified 'from'
	    address in one of three conditions:
	      (a) The user invoking sendmail is a 'trusted' user.  (Typically
		  root, sendmail, daemon).
	      (b) Sendmail is being run by root.
	      (c) The from address contains a '!'.
	    The last of these options is there specially to accomodate UUCP,
	    because you can not reliably assume that rmail is run by a
	    trusted user.  A local user may do a 'uucp' command, which
	    initiates a connection, and collects remote mail.  Since many
	    versions of 'sendmail' determine the user from the getlogin()
	    command, the login name of this user will be used to decide if
	    trusted.  Usually the answer will be no.

 All in all, modifying the code of the mac to conform to UUCP standards is
likely to be the most reliable and simplest approach.
-- 
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
  Neil W. Rickert, Computer Science               <rickert@cs.niu.edu>
  Northern Illinois Univ.
  DeKalb, IL 60115.                                  +1-815-753-6940