Re: Configuring Exim for mail delivery

From	mo <mo777@gmx.net>
Newsgroups	linux.debian.user
Subject	Re: Configuring Exim for mail delivery
Date	2016-10-01 14:10 +0200
Message-ID	<snrh8-8fA-13@gated-at.bofh.it> (permalink)
References	<sncBs-6LW-5@gated-at.bofh.it> <snosV-6bg-7@gated-at.bofh.it> <snqO5-7NL-17@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Am 01.10.2016 um 13:36 schrieb Mark Fletcher:
> On Sat, Oct 01, 2016 at 11:06:07AM +0200, mo wrote:
>>
>> I think i should elaborate a little more on my setup.. i guess i did not
>> make that very clear in the first place, sorry about that.
>>
>> My network is consisting of the following systems:
>>
>> Main PC - 192.168.23.11  (Running Debian Jessie)
>> Server  - 192.168.23.200 (Running Debian Jessie)
>>
>> The server is always online, the PC is only half of the day on.
>>
>> What i want to do now is the following:
>>
>> Sending mail from my Main PC to my Server and also the other way around,
>> from the Server to my Main PC.
>> The Server should also be able to send mail to the "outside" (Meaning to
>> other SMTP servers).
>> The second requirement is optional since i dont own a domain and all this is
>> sitting locally at my home. The most important thing for me is to send and
>> receive mail from both systems in my home network.
>> I hope this made my problem a little clearer :)
>>
>
> Right. So you get mail going back and forth between your two machines,
> server and PC, by creating and populating the hubbed_hosts file I
> talked about in my previous mail, on both machines, pointing at each
> other of course.

I created the hubbed_hosts file under /etc/exim4 and it now works fine, 
i can send mail from my server to my pc and vice versa :)

> If you want to ping the server from the client, you should be able to do
> "ping server.local" from your PC (obviously replace the actual name of
> your server, which you didn't include in your mail, where I put server).
> What is happening if you do that is your PC is saying "get me the
> address of server.local!" and the Avahi daemon on your PC either already
> knows that, or sends out a broadcast message to your network saying "is
> there a server.local in the house???". The Avahi daemon running on the
> server responds to that saying "yes, I'm here, and my IP address is
> 192.168.23.200!". The Avahi daemon on your PC responds to whatever did
> the asking (ping in this case) with the required IP. Ping then requests
> that packets be sent to IP address quoted. By this mechanism computers
> on the same LAN can communicate with each other peer to peer without
> fannying around with full-blown DNS, which is what Avahi is for. That is
> installed by the Jessie installer by default as far as I can tell, so
> both your machines should have it. It doesn't require any configuration,
> so if you haven't touched it, it should work as I have described.
> Although obviously, you have to substitute the real names for your
> server and PC (but you *do* require the .local unless you have configured
> Avahi to use something else)

I'm currently not using avahi as a matter of fact, but it works all fine 
without it ;)
(I have static entries in the /etc/hosts file for my server and for the 
pc - on each system of course)
I have never really worked with avahi... i kinda ask myself why do i 
need it if i can just use DNS or static entries in /etc/hosts. 
/etc/nsswitch.conf is also configured to lookup the /etc/hosts file first.
I know this question is OT, but since you mentioned avahi maybe i can 
ask you what kind of benefits avahi can offer me? :)
(I'm having a statically configured network with 4 machines)

> If you used the default config of exim4 the hubbed_hosts router is set
> up and waiting to be used. All you need to do to enable it is to
> populate the hubbed_hosts file as I described. The other thing you need
> to do is follow Liam's advice, except importantly what needs to be set
> there is the "domain" of the local PC (on the local PC) or the server
> (on the server) only. So the PC will accept mail for pc.local (or
> whatever your pc is called) and the server for server.local (or whatever
> the server is called). Then, you will be able to email yourself at the
> server from the PC by sending a mail to mo@server.local, where I am
> assuming your user name on the server is mo and the server's machine
> name is server. Obviously you would substitute real names. And to go the
> other way, from the server, you could send a mail to yourself on the PC
> by mailing mo@pc.local.

I have asked that before i believe, sorry if this question shows up 
twice.... But why do i even need to set up hubbed_hosts?
I don't really understand why... Should exim not consider the /etc/hosts 
file to resolve the ip of my pc or server (Which i have entered there)
Also i have seen (before it worked) in the log that i get a "destination 
unreachable"... I just don't understand why exim needs to rely on the 
hubbed_hosts being set up?
(I hope you can understand what i mean, if not i will try my best to 
make it clearer :D )

> Let's take a moment to go through what happens if you send a mail from
> PC to server with everything set up as it should be.
>
> On the PC you create a mail and address it to mo@server.local. Let's
> imagine you use mutt to create it. And let's assume mutt is using its
> default configuration to send the mail, which is to call sendmail. And,
> since you have installed exim4, exim has overridden sendmail to actually
> be calling exim4. So, when mutt sends a mail, exim4 running on your PC
> gets handed the mail.
>
> The first thing it does, is say is this mail for this domain. Hmmm. I am
> pc.local. This mail is going to server.local. That ain't me. So not
> local delivery. OK, next I will try hubbed hosts. Do I have any
> hubbed_hosts? Let's look in the hubbed_hosts file. Yep, I do. Can i find
> the @server.local domain in the hubbed_hosts file? Yes, I can. Right,
> where do I send it then? Ah, I send it to a machine called server.local.
> OK... Oi! Network! Gimme the address for server.local....... (this is
> where Avahi does its thing)...Thanks! Right, Connect to 192.168.23.200
> port 25!
>
> At this point the exim4 running on your server gets a dig in the ribs,
> wakes up, and responds to the connection. The two exim4s talk to each
> other and the net result is the mail gets transferred from the exim4
> running on the PC to the exim4 running on the server.
>
> Then the exim4 running on the server goes through the same rigmarole,
> except it finds that the mail IS addressed to a local address, so it
> goes into delivery mode and the mail finds its way into the right
> mailbox on that machine.
>
> Now let's consider what would happen if you tried instead to send a mail
> to the debian user mailing list from your PC (but the same would apply
> to your server). You can't do this using mo@pc.local, because A) your
> ISP most likely won't let you and B) most recipient domains will reject
> that. Instead you have to use a "real" email address, ie one provided by
> your ISP or something like a gmail account or similar. You'll have to
> have configured exim4 in smarthost mode and you will have to have
> configured exim4 to know what your outgoing mail server name is. For
> example, for the specific case of sending to this mailing list, I use
> gmail for outgoing mail and their server name is smtp.gmail.com if I
> recall correctly. You'll also have had to put your email user name and
> password into a file called passwd.client in your /etc/exim4 config
> directory. Since this contains your email password, make sure the file
> is owned by root and not world readable!
>
> Then, any address that isn't local to the machine, and also isn't in the
> hubbed_hosts file, will be treated as external and exim4 will connect to
> the smarthost (your email provider's server) and pass on the message to
> be delivered by it.
>
> Net result -- you send an email from PC to Server, it gets delivered
> directly by a conversation between the two exim4 instances. You send a
> mail anywhere else, it gets handed off to your real-world (not that the
> inside of your home is not "real"!) email provider for delivery.

Very great and detailed explanation, thank you very much! :)

> Now, a word on exim4 config. Be sure to read the *DEBIAN* wiki etc on
> configuring exim4, as the DEBIAN config is a bit different to what you
> will find upstream. Let me save you a bit of time.
>
> First, there are two ways to configure exim4, using one big config file
> which is found in /var/lib/exim4, or using a config directory containing
> a bunch of small config files each handling one small piece of the
> configuration. Opinions abound on which is better, I have no opinion. By
> default, exim4 on Debian will use the single file approach. Second,
> Debian constructs the config file by using a TEMPLATE to be found in
> /etc/exim4, and a second configuration file called
> update-exim4.conf.conf (yes, the conf file for updating the conf
> file......) You put your specific config in the update-exim4.conf.conf
> file, then when you are done you run update-exim4.conf as root
> (update-exim4.conf is actually a program, not a conf file...
> update-exim4.conf.conf is a conf file...) and restart exim4. The
> update-exim4.conf program combines the template with the specific info
> in update-exim4.conf.conf and writes the result to
> /var/lib/exim4/config.autogenerated which is the config exim4 on Debian
> uses. This can also be done by running dpkg-reconfigure exim4.conf as
> Liam suggested, but I think there are more things you can do with
> update-exim4.conf.conf than the questions dpkg-reconfigure will ask you,
> so it wouldn't hurt to get familiar with what is going on under the hood
> when you do dpkg-reconfigure, but that's just my opinion.

That sure is nice to know, i will have a look at the wiki page ;)
(This saves me quite a lot of time :D Thx!)

> If you need more specific help on how to get your local exim4 talking to
> an external email provider, or for that matter if you need me to clarify
> anything about getting local machine to local machine email working,
> post back here.

As far as i understood it i need to set up exim as a smarthost of i want 
to send mail of to other smtp servers, for example gmail.
I guess i will try that out as a next step, so i can send myself mail to 
my gmail or gmx account.... Well, since you asked:
Is it enough to run 'dpkg-reconfigure exim4-config" and use the 
smarthost option from the curses menu?

> Also, being able to receive replies to externally sent mails back into
> your machine locally, needs another bit of setup. If you need that, let
> us know and I'll help with that part too (it is where fetchmail comes
> in). But, there is nothing to stop you using whatever mail client you
> use today to read your email as you presumably do now, and you'll see
> the mails you sent locally there in your sent mail (depending on the
> precise behaviour of your provider's mail server)
>
> Hope that helped clarify things. Sorry for the length of this but
> someone has finally asked for help with something I know something
> about, and I'm keen to help! :)
>

Your explanations sure helped me a lot, i can see clearer now, thx for 
that and of course for the long mail ;) Thx! :)

> Mark
>

Greets

mo

Thread

Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-09-30 22:30 +0200
  Re: Configuring Exim for mail delivery Liam O'Toole <liam.p.otoole@gmail.com> - 2016-10-01 00:50 +0200
  Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 04:00 +0200
    Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 12:40 +0200
      Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-01 13:30 +0200
        Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 13:50 +0200
          Re: Configuring Exim for mail delivery Clive Menzies <clive@clivemenzies.co.uk> - 2016-10-01 14:00 +0200
            Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 14:10 +0200
          Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 14:10 +0200
          Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 14:10 +0200
      Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 14:30 +0200
        Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 14:40 +0200
          Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 15:00 +0200
            Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 15:00 +0200
        Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-01 15:00 +0200
          Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 15:10 +0200
          Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 15:40 +0200
            Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 16:20 +0200
            Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-01 16:40 +0200
      Re: Configuring Exim for mail delivery Teemu Likonen <tlikonen@iki.fi> - 2016-10-01 16:00 +0200
        Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 16:20 +0200
  Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 11:10 +0200
    Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-01 12:10 +0200
      Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 12:40 +0200
      Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 14:10 +0200
        Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-01 14:30 +0200
          Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 14:30 +0200
            Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 15:00 +0200
              Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 15:10 +0200
      Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 14:10 +0200
    Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-01 13:40 +0200
      Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 14:10 +0200
    Re: Configuring Exim for mail delivery rhkramer@gmail.com - 2016-10-01 14:20 +0200
      Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 16:30 +0200
    Re: Configuring Exim for mail delivery Liam O'Toole <liam.p.otoole@gmail.com> - 2016-10-01 18:30 +0200
      Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-01 20:20 +0200
        Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 22:50 +0200
          Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-02 00:30 +0200
            Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-02 02:30 +0200
              Re: Configuring Exim for mail delivery Liam O'Toole <liam.p.otoole@gmail.com> - 2016-10-02 13:10 +0200
            Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-02 10:50 +0200
        Re: Configuring Exim for mail delivery Liam O'Toole <liam.p.otoole@gmail.com> - 2016-10-01 23:10 +0200
          Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-02 00:40 +0200
            Re: Configuring Exim for mail delivery Liam O'Toole <liam.p.otoole@gmail.com> - 2016-10-02 02:10 +0200
              Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-02 14:00 +0200
                Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-02 14:50 +0200
                Re: Configuring Exim for mail delivery Gene Heskett <gheskett@shentel.net> - 2016-10-02 15:20 +0200
                Re: Configuring Exim for mail delivery Mark Fletcher <mark27q1@gmail.com> - 2016-10-02 15:50 +0200
                Re: Configuring Exim for mail delivery Brian <ad44@cityscape.co.uk> - 2016-10-02 15:40 +0200
                Re: Configuring Exim for mail delivery Liam O'Toole <liam.p.otoole@gmail.com> - 2016-10-02 17:30 +0200
      Re: Configuring Exim for mail delivery mo <mo777@gmx.net> - 2016-10-01 22:50 +0200

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