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* Re: [OFFTOPIC] Re: [PATCH] Single user linux
@ 2001-04-24 15:11 Jesse Pollard
  0 siblings, 0 replies; 92+ messages in thread
From: Jesse Pollard @ 2001-04-24 15:11 UTC (permalink / raw)
  To: linux-kernel

Tomas Telensky <ttel5535@ss1000.ms.mff.cuni.cz>
> On Tue, 24 Apr 2001, Alexander Viro wrote:
> > On Tue, 24 Apr 2001, Tomas Telensky wrote:
> > 
> > > of linux distributions the standard daemons (httpd, sendmail) are run as
> > > root! Having multi-user system or not! Why? For only listening to a port
> > > <1024? Is there any elegant solution?
> > 
> > Sendmail is old. Consider it as a remnant of times when network was
> > more... friendly. Security considerations were mostly ignored - and
> > not only by sendmail. It used to be choke-full of holes. They were
> > essentially debugged out of it in late 90s. It seems to be more or
> > less OK these days, but it's full of old cruft. And splitting the
> > thing into reasonable parts and leaving them with minaml privileges
> > they need is large and painful work.

Actually, if you view sendmail as being an expert system it is very
cutting edge :-) It can identify a user from very skimpy data if it
is allowed to (fuzzy matching user names). It identifies local hosts
(with FQDN or partial name, or only host name).

> Thanks for the comment. And why not just let it listen to 25 and then
> being run as uid=nobody, gid=mail?

Because then everybodys mail would be owned by user "nobody".

There are some ways to do this, but they are unreliable.

   1. If the users mail is delivered to /var/mail/<username>; then the
      file /var/mail/<username> must always exist.

	This requires ALL MUAs to truncate the file.
	Some MUAs use file existance to determine if there is new mail.
	If it doesn't exist, then no new mail... ever.

   2. sendmail will not be able to create the /var/mail/<username> mail box.

   3. sendmail will not be able to process forwarding mail.
	User nobody should not be able to read files in users home
	directory... .forward files are private to the user...

   4. sendmail will not be able to process user mail filters (same problem
	as forwarding).

	Note: these filters are applied on receipt of mail (saves time and
	disk space since the filter can discard mail immediately or put it
	in appropriate folders immediately).

-------------------------------------------------------------------------
Jesse I Pollard, II
Email: pollard@navo.hpc.mil

Any opinions expressed are solely my own.

^ permalink raw reply	[flat|nested] 92+ messages in thread

end of thread, other threads:[~2001-04-27 20:07 UTC | newest]

Thread overview: 92+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
     [not found] <Pine.LNX.4.33.0103181407520.1426-100000@mikeg.weiden.de>
2001-03-18 14:43 ` changing mm->mmap_sem (was: Re: system call for process information?) Rik van Riel
2001-03-18 18:13   ` Linus Torvalds
2001-04-24 11:44     ` [PATCH] Single user linux imel96
2001-04-24 12:04       ` Alexander Viro
2001-04-24 12:44         ` imel96
2001-04-24 12:58           ` Daniel Stone
2001-04-24 13:27             ` imel96
2001-04-24 13:38               ` Daniel Stone
2001-04-24 14:04                 ` problem found (was Re: [PATCH] Single user linux) imel96
2001-04-24 14:06                   ` Daniel Stone
2001-04-24 14:47                     ` Xavier Bestel
2001-04-25 18:13                   ` Paul Jakma
2001-04-25  0:01                 ` [PATCH] Single user linux Aaron Lehmann
2001-04-25  0:07                   ` Daniel Stone
2001-04-25  0:16                     ` Alan Cox
2001-04-25  0:34                       ` Daniel Stone
2001-04-25  0:52                         ` Gerhard Mack
2001-04-25  7:46                           ` Ronald Bultje
2001-04-25 14:17                             ` Disconnect
2001-04-27 20:06                               ` Jim Gettys
2001-04-26 19:41                           ` Pavel Machek
2001-04-27 19:00                             ` Erik Mouw
2001-04-27 13:12                         ` Robert Varga
2001-04-27 12:42                           ` [OT] linux on pda was " Collectively Unconscious
2001-04-27 19:05                             ` Erik Mouw
2001-04-27 13:34                           ` Daniel Stone
2001-04-25  0:20                     ` Aaron Lehmann
2001-04-25  0:32                       ` Daniel Stone
2001-04-25  0:35                         ` Aaron Lehmann
2001-04-25  0:43                           ` Daniel Stone
2001-04-25  7:45                         ` Alan Cox
2001-04-25  7:55                           ` Daniel Stone
2001-04-25 15:07                           ` Jonathan Lundell
2001-04-25 14:42                         ` Jordan Crouse
2001-04-26 19:47                         ` Pavel Machek
2001-04-25  1:12                       ` Disconnect
2001-04-25  0:26                   ` Jonathan Lundell
2001-04-25  7:13                     ` Mike A. Harris
2001-04-26 19:54                       ` agenda & vtech helio [was Re: [PATCH] Single user linux] Pavel Machek
2001-04-25  7:04                   ` [PATCH] Single user linux Mike A. Harris
2001-04-26 19:35                 ` Pavel Machek
2001-04-27 14:26                   ` Daniel Stone
2001-04-24 13:40               ` Mohammad A. Haque
2001-04-25  5:29               ` Ben Ford
2001-04-24 12:59           ` Alexander Viro
2001-04-24 13:02           ` Sean Hunter
2001-04-24 13:03           ` Roland Seuhs
2001-04-24 13:50             ` Mike A. Harris
2001-04-24 13:13           ` Richard B. Johnson
2001-04-24 13:37             ` imel96
2001-04-25  7:57               ` Helge Hafting
2001-04-25 10:42               ` Albert D. Cahalan
2001-04-24 14:03           ` Alan Cox
2001-04-24 14:10             ` imel96
2001-04-24 14:27               ` Mike A. Harris
2001-04-24 14:30               ` Alan Cox
2001-04-24 15:07             ` Jeremy Jackson
2001-04-24 17:43           ` Russell King
2001-04-24 18:37           ` Garett Spencley
2001-04-24 12:51       ` Mohammad A. Haque
2001-04-24 13:07         ` Alexander Viro
2001-04-24 12:52       ` [OFFTOPIC] " Mike A. Harris
2001-04-24 13:18         ` Tomas Telensky
2001-04-24 13:34           ` Mohammad A. Haque
2001-04-24 13:40             ` Alexander Viro
2001-04-24 14:18               ` Alan Cox
2001-04-24 14:22                 ` Alexander Viro
2001-04-24 14:37                   ` Alan Cox
2001-04-24 14:41                     ` Alexander Viro
2001-04-24 14:47                     ` CaT
2001-04-24 14:59                       ` Alan Cox
2001-04-24 15:11                         ` CaT
2001-04-24 15:53                           ` Alan Cox
2001-04-24 16:04                             ` Alex Riesen
2001-04-24 17:02                             ` Jesse Pollard
2001-04-24 17:16                               ` Alan Cox
2001-04-24 17:30                             ` Markus Schaber
2001-04-24 14:30                 ` Gábor Lénárt
2001-04-24 14:49                   ` Pjotr Kourzanoff
2001-04-24 14:56                     ` Gábor Lénárt
2001-04-24 14:59                     ` CaT
2001-04-24 15:17                       ` Pjotr Kourzanoff
2001-04-24 14:50                 ` Gerhard Mack
2001-04-24 15:00                   ` Alan Cox
2001-04-24 13:37           ` Alexander Viro
2001-04-24 13:52             ` Tomas Telensky
2001-04-24 14:07               ` Alexander Viro
2001-04-24 19:03           ` David Gómez 
2001-04-25  5:26           ` Ben Ford
2001-04-24 17:55       ` J Sloan
2001-04-24 17:06     ` Stephen Satchell
2001-04-24 15:11 [OFFTOPIC] " Jesse Pollard

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