On Thu, Sep 08, 2022 at 03:42:47AM +1000, Martin D Kealey via Exim-users wrote:
> >
> > Kai Bojens <kb@???> wrote:
>
> > But, then again there is an explicit virtual interface with that IP on my
> > server Host A:
> >
> > ens3: IPv4 & IPv6
> > ens3:402: 1.2.3.4 (IPv4 only)
> >
> > I would have that thought that exim then chooses ens3:402 for outgoing
> > mail, but it decides to use ens3 and IPv6. Is there any way to change this
> > behaviour?
> >
>
> Assuming you're on Linux...
>
> Linux networking simply doesn't work the way that the ifconfig command was
> designed to support, back in the 1980's. Instead the "ifconfig" command is
> lies to you when it shows "virtual interfaces".
>
> Look closely at the output of "ip addr list"; you won't see any virtual
> interfaces, because they're not real, and I don't just mean "not hardware".
> I mean there is no entity in the kernel that corresponds to what you see as
> a virtual interface.
>
> When Exim asks the Linux kernel for the list of interface names, it gets
> given the real interface names.
>
> I suggest using "ip" rather than "ifconfig" so that you see the true state
> of your networking configuration ç
>
> If you want Exim to bind to a specific address, that's plausible; I don't
> know if it already offers that option but if it doesn't it's not a big job
> to add it.
For that, see "local_interfaces" at
https://www.exim.org/exim-html-current/doc/html/spec_html/ch-starting_the_daemon_and_the_use_of_network_interfaces.html
The name says "interfaces" but what it wants is IP addresses and
optional ports. The kernel figures out which interfaces to use from
the addresses.
--
Mark H. Wood
Lead Technology Analyst
University Library
Indiana University - Purdue University Indianapolis
755 W. Michigan Street
Indianapolis, IN 46202
317-274-0749
www.ulib.iupui.edu
