Author: Oleg Cherevko Date: To: exim-users Subject: Re: [Exim] Dynamic helo_data based on outgoing IP?
On Fri, 30 May 2003, Philip Hazel wrote:
> On Fri, 30 May 2003, Oleg Cherevko wrote:
>
> > Perhaps I was not clear enough, but I need _my own_ IP address for this
> > outgoing connection. While $host_address seems to keep IP of the remote
> > end. Or the doc is wrong?
>
> Sorry, I wasn't paying enough attention. There is no variable with your
> own IP address. I kind of assumed you would know it. :-) If you have
> multiple interfaces, you can select which one is used by setting the
> "interface" option in the SMTP transport, but the value doesn't get into
> a variable. However, since you have set it, again you must know it.
>
> What have I missed this time?
Well, setting the outgoing IP with an "interface" option is an alternative
solution to this problem. It works best when your "primary" IP (IP your
hostname resolves into, the one you set with an "interface" option) is
reachable at all times through all of the host interfaces (as ideally
should be, of course).
But suppose that we have host with 2 interfaces that are assigned IPs from
2 different providers in such a way, that it is visible under IP1 via
intreface1 only and under IP2 via interface 2 only (don't ask me why such
a setup, it's a long story). Normally this host default route points to
interface1, so IP1 is its "primary" address, but sometimes interface1 link
fails, so default is dynamically reassigned to point to interface2, and
from now on all of the outgoing tcp session should be initiated with IP2
as hosts local IP. In this case "interface" option-based solution simply
won't work.
BTW, what if $interface_address/$interface_port were defined for outgoing
SMTP connections as well? Is it too worrysome to implement?