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-   -   Fully Qualified Domain Names? (

MasterC 05-15-2003 06:42 AM

Fully Qualified Domain Names?
Ok, so I am trying to setup postfix to work with 2 or more boxes. I am a little confused on what to put where though...

I use one of those cool free Domain Name services that work with Dynamic IP's. It's the one. My Domain name (and website if you are interested) is

Ok, so with that said...

What do I set on each box for "hostname"? I have named one box "masterc" and the other "cooler" so far (in /etc/hosts). So in my file do I set:
? If so, then what? How would I setup "masterc" to get mail from "cooler"?

Ok, so assuming I do set that as "cooler" (Cooler will be running the postfix server), then in $mydomain=
do I put:

Also, does "" count as a FQDN even though I don't actually own ""? I am thinking not since the "masterc." is the indication of a virtual name, but it's resolvable to an actual IP so I am lost (obviously ;) ).

Any info would be greatly appreciated.

My network looks as follows:

==========Phone Jack========
                        DSL Modem 
                      |              |
                      |              |
                    Cooler          MasterC


tangle 05-15-2003 11:44 AM

I might be wrong on this since I have dial-up as the only opton to connect to the internet.

Your ISP assigns only one IP adddress to you. That is the address of the router. This is the address that forwards all web/email requests to. So your router needs to pass those requests to the right box on your local network.

Your hostnames can be what you want as long as it is behind the router. But if you wanted you could make the two PC names and Since you only have authority on the masterC part of the You are accually a sub-domain of

I think that you need to put the server on the other side of the router. Then the severs DSL connection would have the hostname, Then run a proxy such as squid to connect the rest on the network to the internet.

I use to work with a guy that has that set up running FreBSD. If you go to Then go to the SWBell DSL Setup link towards the top of the page. He did a little how to.

Hope I did not confuse you. Also let me know how you got it to work.

MasterC 05-15-2003 11:56 AM

Wow, first off, thank you for the reply!

That sure sounds A LOT more complicated than I had hoped ;) But you definitely clarified some things for me. The 1 thing that I see that I seem to not have mentioned is that my IP is dynamic. It changes, and that's why I use one of the Dynamic Free DNS sites ( has a LInux client that sends my new IP back to their servers when it changes, and then they update their DNS records accordingly).

I'll get to work on all that, and will let you know how things go. Thanks again for the response.


tangle 05-17-2003 11:00 PM

I was thinging the other night while trying to go to sleep (thanks).
I would think that your router would pass the web request on to your server. So your servers name should be Then everything should work great. Since when a web request would be sent to, them they would send it to masterC and the router would send it to cooler.
You would need DNS set up and your DNS server should forward request to your your ISP's DNS servers. You will need to set an MX record for you mail server.
I think this might work, that way you could keep your router.

bulliver 05-18-2003 01:04 AM

I cannot speak for postfix, but I run exim with a no-ip address and it works fine. I don't know how similar the conf files are, but I have this line in mine:
primary_hostname =
Can't help with your network, but I can say that no-ip addresses work perfect as FQDN's

MasterC 05-18-2003 01:02 PM

Thank you for the follow up tangle, and for your addition bulliver. I think I've got it all setup and working now. Everything does seem to be working all right. If I have any more issues I'll be sure to post back :)


tangle 05-19-2003 12:39 PM

Can you tell me what you did to get it working? Thanks

MasterC 05-19-2003 02:38 PM

:D Sorry about that, I actually meant to, I guess I just got side tracked :)

(also, I'm going to be posting a follow up to this about a seperate/related problem, so I really need this info in this thread, thanks for reminding me ;) )

In the for postfix it documents that $myhostname is your FQDN, which if you use a no-ip type service is: SO:
my FQDN is: which goes in my as:

Futher down it documents a $mydomain which it says is your FQDN without the $myhostname Since I don't own the though, I simply left this commented out. Now to email back and forth from box to box I do have to use this format:
user@cooler OR
user@masterc (depending on which machine is recieving the message) and from that I guess it sorts it out (probably from my entries in /etc/hosts).

I'm not home right now, so if I've left anything out, please ask. I'll be glad to clarify.

Thanks again.


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