[ On Monday, May 23, 2005 at 13:34:09 (-0500), Gary Allen Vollink wrote: ]
> Subject: Re: [exim] Bogus HELOs
>
> Who's to say my true canonical hostname is something you will ever find?
>
> In the case where you have a multi-homed host
A multi-homed host does indeed require special support in the MTA if it
is to properly honour the requirement that it utter its true canonical
hostname when acting as an SMTP client.
However there's no magic about it -- just call getsockname() to find the
local address the outgoing connection is bound to. Indeed some MTAs
already include at least primitive support for doing this right
(including Exim, IIUC), and hacking in getsockname() and gethostbyaddr()
to find the name automatically would be trivial in most MTAs too
(including Exim).
However the last time I saw, or even heard of, a true multi-homed SMTP
gateway (that was not a gateway to a private network (*)) was about 15
years ago. :-) [[(*) presumably hosts inside a private network can
trust their own public network gateway host(s)!]]
In any case there really is no valid excuse for any MTA to utter the
wrong hostname when it greets some remote SMTP server on the public
Internet.
--
Greg A. Woods
H:+1 416 218-0098 W:+1 416 489-5852 x122 VE3TCP RoboHack <woods@???>
Planix, Inc. <woods@???> Secrets of the Weird <woods@???>
