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Re: Really a sendmail question

1999-02-27 10:02:06
Bill Moseley <moseley(_at_)hank(_dot_)org> writes:
At 05:48 PM 2/26/99 -0600, Philip Guenther wrote:
    /usr/lib/sendmail -t -oi -oem -ba

Ick.  I would suggest avoiding ARPANET mode, as the sendmail people
want to get rid of it.  Indeed, it was missing from some of the 8.6.x
versions.  Specify the envelope sender directly using the -f flag
instead.

Of course I should try it, but can I use the -f switch running as 'nobody'?

  -fname      Sets the name of the ``from'' person (i.e., the sender of the
              mail).  -f can only be used by ``trusted'' users (normally
              root, daemon, and network) or if the person you are trying to
              become is the same as the person you are.

I don't think I fit into any of those.

The semantics have a changed a few times: originally, sendmail would
ignore a -f flag unless you were listed in the sendmail.cf as a
"Trusted User".  Someone finally pointed out that there were other ways
to do the same thing (like use -ba), so in version 6.28 in May of 1993,
Eric Allman made -f usable by anyone.

Later, in version 8.7, the concept of "Trusted Users" was restored,
however this time it just controls whether or not a
X-Authentication-Warning: header is added if the invoker tries to use
the -f flag to change the envelope sender to someone besides its own
username.


What about this switch?   I'm not sure what 'implies' means here, but it
would seem to, eh, imply that it works like the -ba switch, but in a better
way.  Not sure if that 'implies' also means it looks at From: and Sender:.

  -bs         Use the SMTP protocol as described in RFC821 on standard in-
              put and output.  This flag implies all the operations of the
              -ba flag that are compatible with SMTP.

Ah, no.  The -bs flag tells sendmail to ignore addresses on the command
line and just SMTP on stdin/stdout.  To do this, the program invoking it
has to set up a couple pipes then send back and forth command/response
pairs.  If you don't the details of SMTP, don't bother with this.


BTW -- how does one get the version out of sendmail?

Okay, here is a good use for -bs.  When it enters SMTP mode, sendmail
sends a banner (required by the SMTP spec) which _normally_ includes
its version number.  (You sysadmin may have told it to lie instead, but
that's still relatively rare, I think.)

If you invoke sendmail with the -bs flag, then type "quit", you get
something like the following:

        lunen% sendmail -bs
        220 lunen.gac.edu ESMTP Sendmail 8.9.3/8.9.3/GAC-SUBHUB-2.43; Sat, 27 
Feb 1999 10:42:33 -0600 (CST)
        quit
        221 lunen.gac.edu closing connection
        lunen%

So, the sendmail binary on lunen.gac.edu is version 8.9.3, the config
file is version 8.9.3, and the config file author (me) added a local
version string of "GAC-SUBHUB-2.43".


Philip Guenther

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