Mailing List Archive: Unanticipated qmail ipv6 issue with applications using localhost

Hi John,

--On 7. April 2014 20:30:44 -0400 John Gateley <qmail@jfoo.net> wrote:

> Just an FYI.
>
> I'm using qmail on a server that supports IPv6. I have not made any
> attempt to update qmail or associated tools to IPv6.
>
> Inadvertent use of "localhost" instead of "127.0.0.1" can have bad
> results. In IPv6 localhost translates to ::1, and tcpserver does not map
> this to 127.0.0.1 (I have no idea if it should or not).

It has; this is a default behaviour.

> This means that the tcp.smtp file with single line
> '127.:allow,RELAYCLIENT=""' will NOT set RELAYCLIENT for applications
> connecting to localhost,
> and they will be unable to send to non-local e-mail addresses.

Correct. There may be - in addition - some other side effects, since IPv4
addresses are presented by the kernel als IPv4-mapped IPv6 addresses.
However, there might be a kernel parm disabling this behavior.

> In my case, it was squirrelmail.
>
> Fun debugging.

You should use a IPv6-enabled tcpserver.

You will find my development here:

<http://www.fehcom.de/ipnet/ucspi-tcp6.html>

The qmail community needs to wake up and recognize IPv6 as useful net
protocol.

regards.
--eh.

>
> John
>

--
Dr. Erwin Hoffmann | FEHCom | http://www.fehcom.de/ | PGP-Key-Id: 7E4034BE