Brian wrote: > Every time I use d-i in expert mode I wonder what other people make of > it. I was puzzled by it the very first time and even now think it is > one of the most difficult fields to fill in because the background > knowledge needed isn't immediately as apparent as it is with language > or location, say. The installation manual is really of no help as it > has little commentary on its significance, I only very rarely use expert mode. I almost always use the normal mode. Then I fix up anything I want to change after the installation is complete. > As an example, let us suppose your ISP in the UK is > talktalk.co.uk. You put this as your domain name because that is all > you can think of. After all, it is in your email address and you do > not have your own domain. I am spoiled because for my installations there has always been a valid domain name to use. It is good to be reminded that not everyone has that environment. Thanks. > Your hostname is copernicus. So your canonical hostname becomes > copernicus.bt.com, which doen't exist and doesn't resolve. Now - > what harm is done? No immediate harm. Some strange things with mail routing and so forth. But very few people do local mail delivery these days. And that would be mostly fine regardless. It would provide the domain in the /etc/hosts file. That would make most things happy. > Leaving the field blank often gets you what your > router provides; copernicus.lan in my case. Cool! What mechanism supports that happening? Is the default domain in your router's dhcp config the .lan domain? David Wright wrote: > Quoting David Wright (deblis@lionunicorn.co.uk): > > Do you think there's time to get such advice into jessie's installer > > for domestic users (assuming it's good advice)? > > ... er, or even the opposite advice (appendix G) which shows how > fraught this area is! Yes. Certainly! It is a confusing topic. *I* am confused by the topic of local private domains. It would be good to provide some guidance at installation time. And now a short diversion about Postfix related to hostnames... Previously in Wheezy 7 and before postfix $mydomain defaulted to $myhostname minus the first component, or "localdomain". $myhostname defaulted to gethostname() and if that had no dots it appended $mydomain forming names such as foo.localdomain when the configured hostname was a short name (the general Debian recommendation) rather than a FQDN. That would match the names used in /etc/hosts and everything would work. For a system defaulting to localhost: root@localhost:~# postconf -d myhostname myhostname = localhost.localdomain root@localhost:~# postconf -d mydomain mydomain = localdomain To set correct domains I always set myhostname explicitly to the FQDN in the Postfix main.cf configuration. Setting just myorigin = /etc/mailname (a Debian specific patch) doesn't really set all of the names correctly for a standalone system. root@localhost:~# postconf -d myorigin myorigin = $myhostname AFAICS the defaults of setting localhost.localdomain both in /etc/hosts and in the Postfix config cause the complete loop to be correct and work for the simple standalone unconnected case. It will get localhost.localdomain in both places and the virtual circuit is valid throughout. Local delivery at least works without errors. Of course someone setting up a full mail server will need to assign a valid hostname and a valid domain name. That connects everything correctly too. The "interesting" case is when there is a local hostname that isn't "localhost" but no valid domain has been set. That should never happen on a system trying to be a valid mail server. But it obviously does get set up by users just installing the system and trying to do the best they can with the information they have at the time. That feels like a corner case to me. One that should be discouraged. Having some extra description at installation time to help avoid it would be a good thing in my opinion. It would avoid the cases where 'hostname -f' returns a name without any dots which confuses software written that insists there must be dots in there. Bob
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