Re: [exim-dev] exim question

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Author: Jakob Hirsch
Date:  
To: dcc
CC: exim-dev
Subject: Re: [exim-dev] exim question
Hi,

(CCing exim-dev)

Vernon Schryver, 2010-07-13 19:20:
> http://www.merit.edu/mail.archives/nanog/msg10375.html
> seems to imply that exim violates the SMTP standards by generating
> address literals in Received: headers without the required
> "IPv6:" tag. That NANOG thread seems to say that exim generates
>
>     Received: from s0.nanog.org (s0.nanog.org [2001:48a8:6880:95::20]) ...

>
> instead of
>
>     Received: from s0.nanog.org (s0.nanog.org [IPv6:2001:48a8:6880:95::20]) ...

>
> Is that true?


uhm... yes, that's true:

Received: from calcite.rhyolite.com ([2001:4978:230::3]:30997)
    by ymmv.de with esmtps (TLSv1:AES256-SHA:256)
    (Exim 4.72)


I (and obviously others) wasn't aware that should be a "IPv6:" prefix.
Which "SMTP standards" say that?

> Should I modify the DCC client programs to recognize IPv6 address
> literals without the "IPv6;" tag? It would cost some CPU cycles.
> It might be a little dodgy, because except for colons, IPv6 addresses
> can look like host names.


Parsing Received headers is always dodgy, because it was never intented
to be machine readable.
The Right Way[tm] to do this is to tell the MTA to add a header line
(X-Sender-IP or something).