Author: Phil Pennock Date: To: Fabien LUCE CC: exim-users Subject: Re: [exim] [Newbie] Configure exim for a LAN
On 2010-02-20 at 14:24 +0100, Fabien LUCE wrote: > I'm under Linux Debian.
This means you're not using the Exim default config and everything about
how your configuration file is put together is Different. There's a
file called something like /usr/share/doc/exim4/README.debian which will
point you to the mailing-list where you can ask relevant configuration
questions.
> >>At first, i'd like to understand well what exactly a domain is. I see that
> pretty like a network name.
> And each machine on this network has a FQDN = machine_name.domain_name. To
> this FQDN we can match up IP adresses.
> First of all, do machines of the same domain need to have same class of IP
> adress?
No the don't.
> For example, can i gather under the same domain (domain.org) two machines
> with IP: 10.0.0.2 and 192.168.1.1 ?
Yes. But neither of those addresses is routable on the open Internet,
so if you publish records pointing mail for example.org to hosts with
those addresses, then you won't receive mail. (By the way, "domain.org"
is a real domain, but "example.org" is reserved for use in examples and
documentation).
> >>About domain name resolution. Do i need to configure something special
> other than /etc/hosts for exim to find a local FQDN?
You don't *need* to use DNS for host resolution, but you quickly risk
ending up with inconsistent views of the mappings and problem diagnosis
becomes harder. Also, the default setup assumes use of DNS.
Mail for a domain example.org will first check for an MX record. When
there's no MX record, an attempt will be made to resolve the host using
DNS. (Assuming that you haven't set the "mx_domains" option, that is
(which disables direct-to-A resolution)).
This is why the Router is called "dnslookup". :)
Instead, you need to use a "manualroute" Router.
> Is there something special about some MX to do on the server?
> How can i say to exim to look up on the local network first?
In Exim, each recipient address is tried by each Router in turn. So you
want your first Router to be a manualroute Router which handles the
domains you want.
Something like this should do it, for any host under example.org:
You could also use "transport = remote_smtp_nodns" and define that as
another Transport, in the Transports section of the config file, eg:
remote_smtp_nodns:
driver = smtp
gethostbyname
> >>I'd like to send mail thru my local network.
> First machine (client) is atom.domain.org 10.0.0.1
> Second machine (server) is serveur.domain.org 10.0.0.2
> I want to send mail from client to server.
> What kind of configuration must i put in /etc/hosts, /etc/resolv.conf or
> others...?
You shouldn't need to touch /etc/resolv.conf. You might need to touch
/etc/nsswitch.conf and make sure that the "hosts:" line lists "files"
before "dns". Especially if you're hijacking an existing domain like
"domain.org", which has real MX records.
> When i perform a dpkg-reconfigure exim4-reconfigure, i have serveral choice
> of configuration template:
For this, you'll probably need to ask on the Debian lists.
