Using RNDC to control remote access to my BIND server

Paul Kosinski bind at
Sat Apr 24 00:10:52 UTC 2021

A couple of years ago, I tried using nsupdate to modify a dynamic (DHCP) IP address for my very simple domain. It worked, except that it totally messed up the organization of the zone file. Since the file only has 44 active lines (which are organized logically), I maintain it by hand. After nsupdate made the one line change, the zone file became unmaintainable.

Was this a bug in nsupdate, or does nobody try to understand their zone files.

P.S. Now I use $INCLUDE and just overwrite the included file with the new A record (using a simple bash script via an encrypted connection).

On Fri, 23 Apr 2021 12:21:22 +0200
Anand Buddhdev <anandb at> wrote:

> Hi Greg,
> You don't need to SSH into a remote server to do dynamic DNS updates!
> The "nsupdate" tool can send the dynamic DNS updates directly to your
> remote server over the DNS protocol.
> You appear to be confused about what the various tools do, so here's a
> summary:
> 1. ssh is used to log into a remote server, get a shell, and run
> operating system commands.
> 2. rndc is for controlling a running BIND server. It can be used to
> check the status of BIND, reload it, etc.
> 3. nsupdate is for modifying a zone directly (whether on the local
> machine, or some remote machine) using the dynamic DNS protocol.
> Having read your message, it seems that you need to use "nsupdate". You
> don't need "ssh" or "rndc" for this.
> Regards,
> Anand
> On 23/04/2021 11:50, Greg Donohoe wrote:
> > Thank you for the suggestions. I am looking into those now.
> > Yes we can run nsupdate again on the remote server but I would still need
> > to connect to the remote server to do this.
> > We were thinking of using SSH to the remote server but we want to explore
> > any other option rather than SSH for the secure connection.
> > I was thinking that it may be possible to use RNDC or some other tool to
> > update the remote BIND server zone files (either by modifying the zone file
> > that is already there or replacing the zone file with the new one I created
> > locally).
> > RNDC looks like it is a non starter for what I want but nsdiff may be a
> > good option.  

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