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Message-ID: <20021224162111.GA30426@openwall.com>
Date: Tue, 24 Dec 2002 19:21:11 +0300
From: Solar Designer <solar@...nwall.com>
To: popa3d-users@...ts.openwall.com,
James Olsen <jamesml@...netolsen.com>
Subject: Re: Question about using popa3d and stunnel
On Mon, Dec 23, 2002 at 12:10:55PM -0600, James Olsen wrote:
> SD> Well, someone might be able to help you if you posted your
> SD> configuration (both server and client).
>
> Sorry :) Here is the info:
>
> Output of "stunnel -V":
> stunnel 4.03 on i686-pc-linux-gnu PTHREAD+LIBWRAP with OpenSSL 0.9.6h 5 Dec 2002
Is it possible to build stunnel without pthreads these days? If so,
I'd recommend everyone to do so.
> I'm using version 0.5.1 of popa3d (latest stable release). I don't
> know what has been changed/implemented in any of the stable or the
> development releases, there doesn't seem to be any kind of change-log
> or revision history on the openwall.com website or in the tarballs.
> :(
popa3d change logs are now only available in the Owl package, or you
may get them from the Owl CVS or in the FTP'able Owl source tree.
But I understand the need for change logs in the portable popa3d
package. Your vote counted.
There have been no changes relevant to the problem you're seeing,
though.
> Here is my configuration file I use when starting stunnel:
>
> =======================
> cert=/usr/local/ssl/stunnel.pem
> debug=debug
> output=/usr/local/ssl/stunnel.out
> setgid=unpriv
> setuid=unpriv
>
> [pop3s]
> #protocol=pop3
> accept=995
> exec=/usr/local/sbin/popa3d
> execargs=popa3d
> =======================
Looks reasonable at first glace, but as I've never dealt with a
version of stunnel this recent I can't know if it's right.
Is it still possible to have *inetd accept connections, then start
stunnel and have it start popa3d? This would be slower, but likely
more reliable.
> Given the above configuration, I get the following message in the
> logs:
>
> =======================
> Dec 23 10:22:18 www popa3d[22756]: chroot: Permission denied
> =======================
>
> popa3d is trying to chroot to /var/empty (the default, which is
> compiled into the program)
Hmm. If stunnel starts popa3d as the "unprivileged" user, then that
is wrong. What it should be doing is a sequence like:
1. Start up as root.
2. fork/exec popa3d.
3. Drop to the "unprivileged" user and do all the SSL work, passing
data over sockets and pipes.
Of course, this is likely not compatible with threads. I hope they
at least do the right thing when built without pthreads?
> I'm "newbie" enough I'm not sure how to set this up to work properly
> as an unprivileged user. But /var/empty I believe is supposed to be
> read/writable only by root if I read the popa3d documentation
> properly.
That's correct.
> Doesn't this rule out running stunnel as an unprivileged user?
No. It works here (patched ancient stunnel), see above.
> But, in the meantime, to make sure the rest of my configuration is
> okay I am temporarily letting it run as root (fire it up, test, shut
> it down). And when doing so, the permission denied error goes away and
> then I'm faced with this message:
> 2002.12.23 10:52:54 LOG6[23970:1026]: Local mode child started (PID=23971)
> 2002.12.23 10:52:54 LOG7[23970:1026]: Remote FD=10 initialized
> 2002.12.23 10:52:54 LOG7[23970:1026]: SSL socket closed on SSL_read
Well, something wrong happens at this stage and it's not seen in the
log what exactly that is.
Maybe strace -fF it all?
> My email client is TheBat, which natively supports TLS connections to
> port 995 (also STARTTLS on port 110) and supports four authentication methods:
>
> Regular, MSN (NTLM), MD5 APOP challenge/response (RFC-1734), and MD5
> CRAM-HMAC challenge/response (RFC-2095).
>
> By default, I'm using "regular", which works just fine with regular
> POP3.
I think it should work.
> I also tried MSN (NTLM) just to see if it worked, and it failed
> as well.
It shouldn't work.
> I'm fairly certain that TheBat will still attempt to
> authenticate - I believe something else has failed and because of that
> failure the connection terminates before authentication takes place
> and that is why I'm getting a "didn't attempt authentication"
> messages.
That's right. It seems that stunnel doesn't pass all of the data
to/from popa3d.
> I'm willing to try a different email client (that is known to work
> with stunnel/popa3d) to rule out my email client as the problem if
> anyone has any suggestions on what would be good one(s) to try.
I know people are using Outlook Express with this.
> I've also tried using the "protocol=pop3" configuration in the stunnel
> config file, but then I get this series of messages in the logs:
I don't know what this means for current stunnel. Maybe STLS? Then
it should be on port 110, not 995.
--
/sd
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