openresolv-discuss

Hi Fred

On 17/09/2019 11:03, Fred Brennan wrote:
> Greetings,
>
> I apologize if this has been discussed before; there is no way to check as the
> archives are down.

Archives are up here:
https://roy.marples.name/archives/openresolv-discuss/

> I use Arch Linux, the bundled `resolvconf` command is openresolv. I was trying
> to do something I thought simple, add the nameserver 127.3.2.1 (yes it's
> valid) to the top of the list, such that we receive:
>
> # Generated by resolvconf
> domain bbrouter
> nameserver 127.3.2.1
> nameserver 8.8.8.8
> nameserver 8.8.4.4
> nameserver 1.1.1.1
>
> However, it seemed that no matter what I set `name_servers` to be, I would
> receive:
>
> # Generated by resolvconf
> domain bbrouter
> nameserver 127.3.2.1
>
> The documentation proved hopeless. After 20 minutes of trying, I read the
> script itself (`vim `which resolvconf``), and came across a group of lines
> which mystified me:
>
>                          for l in $local_nameservers; do
>                                  case "$stripped_line" in
>                                  $l)
>                                          islocal=true
>                                          break
>                                          ;;
>                                  esac
>                          done
>
> So...if the nameserver matches 127.*, this causes no other nameservers to be
> added after!! This is seemingly documented nowhere. The resolvconf.conf
> manpage does not mention this "feature". Neither does the resolvconf manpage.

resolvconf.conf(5): LIBC_OPTIONS

     resolv_conf_local_only

     If a local name server is configured then the default is just to
     specify that and ignore all other entries as they will be
     configured for the local name server.  Set this to NO to also
     list non-local nameservers.  This will give you working DNS even
     if the local nameserver stops functioning at the expense of
     duplicated server queries.

> With the actual script contents in mind, this solves the problem:
>
> local_nameservers=""
> prepend_nameservers="127.3.2.1"
>
> I do not understand why fallback nameservers are ignored when a local
> nameserver is on the list, or why by default 127.* is a showstopper. I assume
> you have good reasons for this. This behavior however should be documented.
>
> Please consider documenting this side effect of local_nameservers.

Hopefully the snippet I posted from the man page is sufficent 
documentation for you and explains why it's the default.
If not, please consider submitting a patch for the man pages.

Roy