[6bone] Re: Some problems with sendmail, Linux and v6

[Michael Kjorling]

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On May 16 2002 20:01 -0300, Allan Edgard Silva Freitas wrote:

> I compiled both Sendmail 8.9.1 with WINE patch and Sendmail 8.12
> using -DNETINET6 option and I see if I use at the same time the two
> lines below in sendmail.cf:

> "O DaemonPortOptions=Name=IPv4, Family=inet"         ("O DaemonPortOptions=Family=inet6" in /etc/sendmail6.cf using WINE)
> "O DaemonPortOptions=Name=IPv6, Family=inet6"       ("O DaemonPortOptions=Family=inet6" in /etc/sendmail6.cf using WINE)
>
> I get no runing sendmail, I can only use:
> "O DaemonPortOptions=Name=IPv4, Family=inet"
>     or
> "O DaemonPortOptions=Name=IPv6, Family=inet6"
>
> So, I only could have an IPv6 SMTP Server or an IPv4 SMTP Server but
> never the both running. I had a FreeBSD box, where IPv6 is native
> and I see that the same configuration have no problems in Free. Do
> anyone know some specific bug regarding about this configuration
> above described? Some hint to I overpass it??

Hmmm... I have sendmail accepting connections over both IPv4 and IPv6
on a dual-stacked Linux 2.4.18 box with no problem, and every now and
then I do get a mail in my inbox that has travelled over IPv6 - even
though most are still, obviously, IPv4.

Here's what I have in my sendmail.mc that relates to this:

	dnl DAEMON_OPTIONS(`Port=smtp, Name=MTA-IPv4, Family=inet')
	dnl DAEMON_OPTIONS(`Port=smtp, Name=MTA-IPv6, Family=inet6')
	DAEMON_OPTIONS(`Port=smtp, Name=MTA, Family=inet6')

As you can see, I effectively only have one DAEMON_OPTIONS() line,
giving Family=inet6. There is some peculiarity with the Linux kernel
that an IPv6 listening socket will also accept IPv4 connections - it
was in the original standard but experience has shown since then that
it does not always produce the desired results.

Anyway, why don't you go ahead and try your sendmail over IPv4 with
only an AF_INET6 socket listening? Provided that you have a stock
kernel release that might do the trick.

I'm running sendmail 8.11.6 compiled with IPv6 support (of course) in
case that matters.


Michael Kjörling

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Michael Kjörling  --  Programmer/Network administrator  ^..^
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