This script automatically changes the allowed IP on Webmin, depending on the dynamic IP assigned to the machine you are connecting from.
It is available in PowerShell and Bash Shell.
If you connect to your Webmin/Virtualmin instance remotely (for example on a VPS) from a dynamic IP or changing VPN, this script is for you.
On Webmin, you can decide to allow connections only from selected ip numbers or hostnames. This is a great security feature, however useless if you have a dynamic IP, like most people do, or if you use a random VPN machine to connect.
Previously, to make use of this feature you'd have to subscribe to a DDNS service such as Dynu or NoIP, have them associate a given hostname to your current IP number, and set up Webmin to only allow that particular hostname.
This is a solution replete with problems, as it relies on one company's good will to provide you with this free service for times to come. Furthermore, most likely it means allowing their app to always run in the background on your machine, in order to monitor your IP changes.
Not anymore.
- It will discover your IP number against a free IP service such as Icanhazip or ipify;
- Connect to your remote server, retrieve the
/etc/webim/miniserv.conffile Webmin uses for settings; - Check whether the
allow=line already contains your current IP number (if yes, exit the script); - If not, modify it so that the IP number is current (it will append the current IP to the list, if multiple IPs/Hostnames are allowed, removing the previous dynamic IP number);
- Restart Webmin.
On Windows, this script connects to your server via SSH using Plink (part of the Putty package). Therefore, it requires you to:
- Have Putty present on your machine;
- Customize the script, providing the path to the Plink executable (if not in
$PATH, or the script directory); - If you want the script to send a system notification when the IP has been changed, you need to make sure the BurntToast extension to PowerShell is installed.
- To run a PowerShell script on Windows, you need to set Execution Policy in PowerShell, using this command:
Set-ExecutionPolicy RemoteSignedas Administrator.
Furthermore, whether you are on Windows or Linux, you will have to customize the script, providing:
- Path to the
miniserv.conffile (usually/etc/webmin/miniserv.conf) - IP number/hostname of remote server
- username (user shoud have write privileges to
miniserv.conf) - SSH port (usually
22) - Host Key public fingerprint (in the
key-type:host-keyformat; can be retrieved via SSH or from within Webmin SSH server settings. The host public key honestly is not always necessary, once it is saved in the SSH cache. I've found this to be a requirement only under Windows, and probably only the first time the script runs.)
Most importantly, it is essential that you have a running SSH agent (such as Pageant under Windows, also included in Putty) with the respective SSH-RSA key loaded for the user1. (I assume you don't want to write down sensitive credentials inside this script.)
- Download the script
- Place it wherever is convenient for you (best kept in its own folder, as it will create a small file when in use)
- Set up a cron/scheduled task to run this script in the background whenever you deem necessary (it could run every half hour, once a day, it could be ran only when connecting to the internet, etc.)
- Alternatively, you could run the script manually whenever you are about to connect to Webmin.
The script is "portable". It will write one necessary file into its own directory (this file can be shared between the PowerShell and Bash scripts), and will look for icons for the notifications within the same directory. By keeping all the files in their own folder, the script can work from any machine.