Name resolution with unqualified names

[Kevin O'Gorman]

On Sat, Nov 25, 2017 at 2:30 AM, Xen <list at xenhideout.nl> wrote:

> Kevin O'Gorman schreef op 25-11-2017 5:10:
>
> 1. I'm not aware of having installed a DNS server.  Camelot is running
> Xubuntu, one other machine is running Ubuntu, two are running a server
> version of Ubuntu.  Perhaps some or all have a DNS server, but it's not
> because of anything I planned, so I don't know much about it.
>
> 2. The means to do the configuration you mention was exactly my question.
> I used to edit /etc/resolv.conf, but it is no longer a file.
>
>   If you can help me with item #2, I'll be very grateful.
>
>
> If one server is always running you can install dnsmasq on it, switch off
> DHCP on the router, create a minimal dnsmasq configuration that I can tell
> you,
>
> Tell dnsmasq to either use the router or some global thing for DNS.
>
> But at that point you:
>
> - are dependent on that server for your entire network
> - may not have an easy interface to see DHCP leases, until you point a
> webserver to its leases file.
>
> So it would be easy enough to configure e.g. lighttpd on port 81 to point
> directly to /var/lib/dnsmasq/lease/dnsmasq.lease
>
> At this point your server does both DNS and DHCP.
>
> Because it does DHCP, it gives itself as the DNS server for your network.
>
> If all your computers have hostnames configured, they will send this
> hostname over DHCP to the dnsmasq server, which will add it to the list of
> hosts it has.
>
> This list is then used for DNS.
>
> The only issue is the .local issue mentioned, but this only happens when
> you use .local explicitly.
>
> As long as you don't use .local explicitly, your ordinary unqualified
> names will still resolve to .local, but the mdns_minimal plugin will not
> stop it.
>
> This is the minimal dnsmasq.conf setup as mentioned:
>
>
> no-resolv
> expand-hosts
> domain-needed
> bogus-priv
>
> server=8.8.8.8        <-- upstream dns server, can be your router
> local=/local/         <-- domain you use for automatic resolving
> auth-zone=local       <-- only adds a SOA record
>
> domain=local,192.168.0.0/24    <- attaches the subnet to the domain
> dhcp-option=option:router,192.168.0.1    <-- configures the gateway
>
> dhcp-range=192.168.0.100,192.168.0.199,12h    <-- configures the dhcp
> range
>
> dhcp-host=hostname,192.168.0.50   <-- configures a static DHCP IP for a
> given hostname
>
> dhcp-host=00:1f:c6:25:10:e8,192.168.0.6,40000s   <-- does the same based
> on MAC address
>
> and adds a timeout.
>
> dhcp-option=option:classless-static-route,10.8.0.0/24,<serverip>    <--
> if you have additional static routes such as VPN
>
>
> that you want all clients to have.
>
> mx-host=server.local,server.local             <-- if you want anything to
> be a mailserver
>
> You can set up an internal mailserver in this way.
>
> You can have emails like kevin at local
>
> Or kevin at camelot.local
>
> Or kevin at camelot
>
> You can add mx records to each individual host so that each individual
> host can now receive emails from other hosts.
>
> "self-mx"
>
> and so on and so on.
>
> But this is all you need with a bit more.
>
> Finding all that to be somewhat less than immediately intelligible, I
anticipated a considerable learning curve.  Another approach occurred to
me.  Since all of the IP numbers are reserved, there's no need to get them
from a DNS server of any kind, or interfere with the organization of
/etc/resolv.conf.

Also: /etc/hosts is still a file, and can hold this information.

Accordingly, I'm working on scripts to gather and distribute the relevant
information in such a way that any future changes can be propagated quickly.

-- 
Kevin O'Gorman
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