Dynamic IP changed overnight - how do I automate updating my Public IP across all servers?

GJSchaller · August 31, 2023, 7:42pm

Exit 0 seems to work for me - I am not getting the notifications after the first run.

I’ll need my home IP to change, to see if it runs again and everything updates. Hopefully, it will!

Ilia · September 1, 2023, 12:31pm

It should really just work! Please let us know if you have any issues with it.

It is also discussed here:

github.com/virtualmin/virtualmin-gpl

Feature Request/Change: Dynamic IP Update Tool

opened 06:09PM - 31 Aug 23 UTC

ksihota

Based on a discussion in the forums https://forum.virtualmin.com/t/dynamic-ip-c…hanged-overnight-how-do-i-automate-updating-my-public-ip-across-all-servers/122364 I thought I would add this in here. This has to do with how the Dynamic IP Update is currently working which does not appear to make sense to me. Maybe I am misunderstanding the real purpose of this tool or can't get beyond my own case use and perspective. My assumption was that the tool makes it easy to internally change IPs when the main IP is dynamic and may change over time. These are the options DynDNS - use the built in script if you subscribe to their service. Don't Update - only make internal changes to virtual server ips Run External Script - use your own script to update external host records My expectation was that the tool would provide the old and new Ips, would initiate a change to all internal IPS when active and would only trigger a script when the IP actually changed. I also thought that by filling in some of the other fields like username, password, and Hostname that these variable would also be available to the user provided script. From what I can tell this does not appear to be how the tool works. The discussion includes this comment from me as I try to explain my understanding. ___________________________________________________________________________________________ I was looking at the Dynamic IP Update tool in Virtualmin as a way to trigger the process but GJSchaller reports that it is being called every 5 minutes regardless of an IP change or not. I misunderstood the use of the tool. I was expecting that it was monitoring the IP in use, in the background, and when the IP changed it would provide the old IP the new IP and a few other variables listed in the dialog and that information could be used in an exteranl script. At the same time, if it was set to Active, it would go ahead and change the internal IPs listed for each virtual server and update Webmins IP settings. I was going on the help info provided (in the dialog) but couldn’t find any more detailed info until Illia gave me the information on the Virtualmin commands. ![image](https://github.com/virtualmin/virtualmin-gpl/assets/29150649/eaca7c80-21c7-4074-87aa-ec2f865dd864) Since it only has DynDNS listed (I don’t use them) I figured that running an external script allowed me to define a script that altered my Registrar’s Host records myself. My reasoning was that DynDNS was a service already supported, but if you used something else you would create your own script to interact with your host records meaning that Webmin/Virtualmin would not have to create a bunch of different scripts for all the different dynamic DNS providers. Since I already had a script made, I assumed I could call my python script (the one that interacts with my registrar) and use several variables passed from this Dynamic IP Update tool to my script. It would simplify my setup in a couple of ways. It would not require me to use a cron job to monitor my IP and it would save me from actually storing the current and changed IPs on my system in a file (that my script checks for a change to initiate the host record change.) It would also automatically update the the virtual servers within webmin/virtualmin to the new IP, eliminating the warning message I get in Webmin and the need for me to manually change the IPs for my virtual servers. Apparently that’s not how this Dynamic IP Update tool works. From this thread it appears it will run a script using a virtualmin command that will update the internal IPs for any virtual server. Not sure why it works that way. Looks like you can get it to run any command line command simply by adding it into a scripts and that it will run every 5 minutes. I can do that with a cron job. I’m not sure why the command virtualmin modify-all-ips --default-old-ip --detect-new-ip has to be added as the external script since it should be one of the purposes of this function in the first place. In my way of thinking the process should be: 1. Monitor IP for changes and begin the process when it happens 2. Send the new IP of the server to the DNS provider to change the host records (DynDNS or External script or Skip) 3. Change all the internal (virtual server, webmin etc.) ips to the new IP 4. Log changes 5. Send a report indicating success or failure

ksihota · September 2, 2023, 3:41am

Please Report back with any results.

I have rewritten my python script and have moved it all to the shell script and used the New IP and Hostname command Parameters $1 and $2 to hopefully update my DNS Host Records at my Registrar.

I will have to wait for an IP change as well before I will know if I did it correctly.

Ilia · September 2, 2023, 11:28am

What your Python script is doing exactly? Because VIrtualmin is already performing all IP changes on its side.

xlad · September 2, 2023, 3:22pm

I suppose that takes the old IP and the new IP and change ns on registrar, and @ksihota would like that VItualmin also update its part of domains…

I may be wrong

ksihota · September 2, 2023, 5:12pm

The python script ran on a cron job (I think I had it going every 5 min) and stored a copy of the server’s IP address in a local file. It compared the current IP with the last one saved. If they were the same it would exit. If they were not the same it would update my host records (on my registrar’s server.)
It also read the response back and logged any returned info.

Then I would manually change the IP information on the server for any virtual server that needed it when Webmin indicated the IP change had happened. I seem to recall that all I had to do was select something in Webmin when it warned me. If it didn’t work properly I would change the virtual server info in the apache config file.

Now, my understanding is, by using the Dynamic IP Update tool, Virtualmin will take care of the internal virtual server ip updating, and all I needed to do is to change the host records. Since the 5 min checks are handled by the tool I can skip the cron job.

The new IP is provided as a command parameter ($1) so I can now just send the new IP to the registrar in a script. I therefore changed from python to a shell script and removed all unnecessary code.
Now the new shell script just sends the new IP($1) and the Hostname ($2) to my registrar to change my records.
It still includes a loop to update all the records (sub domains.)
If the script is only run when a new IP is recognized I no longer need to provide a change_of_IP check and the Update_Host_Records will run and complete all the updates.

What I am still unclear on is:
Since the Dynamic IP Update tool is supposed to be taking care of any local IP changes, why is the Virtualmin command:
virtualmin modify-all-ips --default-old-ip --detect-new-ip
needed to be called in the script?
Isn’t that the point of the tool?
Shouldn’t this be called as part of the Dynamic IP Update tool as its basic function or is it only applied when using the dynDNS option and not included when the other two options are used?

I am also not clear as to the use of some of these

If I select Dynamic update enabled (No) I would expect that the tool is disabled?
What does selecting Don’t update any service do?
Isn’t that the same as the first option or are other things happening?

Wouldn’t it also make sense to make these variables available for scripting in case they were useful?

My service requires a password which I just add in the script but it feels strange to me, that the tool provides the option to use this but it only applies to dynDNS?

Like I said in other comments, I am probably only viewing this from my own perspective and not seeing it as other are. I don’t have any experience using dynamic DNS tools and really only have the one simple task to take care of if my dynamic IP changes on my server.
I rely on you experts to do the heavy lifting, and I really appreciate all the hard work and effort you guys put into this to make it easier for the rest of us.
Thanks again for all your help.

Ilia · September 2, 2023, 6:12pm

You don’t need to run it from inside of your custom script, it will be handled by Virtualmin automatically.

xlad · September 2, 2023, 7:11pm

You can always check the code at:

github.com

virtualmin/virtualmin-gpl/blob/master/dynip.pl

#!/usr/local/bin/perl
# Update the configured dynamic DNS service

package virtual_server;
$main::no_acl_check++;
$no_virtualmin_plugins = 1;
require './virtual-server-lib.pl';
&foreign_require("mailboxes");

exit(1) if (!$config{'dynip_service'});

$h = &get_system_hostname();
($svc) = grep { $_->{'name'} eq $config{'dynip_service'} }
	      &list_dynip_services();
$from = &get_global_from_address();

# Check if we need to update
($oldip, $oldwhen) = &get_last_dynip_update($config{'dynip_service'});
$newip = $config{'dynip_auto'} ? &get_external_ip_address()
			       : &get_default_ip();

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and

github.com

virtualmin/virtualmin-gpl/blob/master/dynip-lib.pl

# Functions for updating a dynamic IP address

# list_dynip_services()
# Returns a list of supported dynamic DNS services
sub list_dynip_services
{
return ( { 'name' => 'dyndns',
	   'desc' => $text{'dynip_dyndns'} },
	 { 'name' => 'none',
	   'desc' => $text{'dynip_none'} },
	 { 'name' => 'external',
	   'desc' => $text{'dynip_external'},
	   'external' => 1, },
       );
}

# get_last_dynip_update(service)
# Returns the IP last sent to this dynamic DNS service, and when it was
# sent (if called in an array context)
sub get_last_dynip_update

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