Ubuntu

Yes, but having your public dynamic IP address "change rarely; typically less than once a month" is a non-contractual unique situation which is mostly "a fluke" versus a contractually obligated service. My IP address changes daily or more often, so if I needed a static public IP address, for any reason, I would just pay for it. After all, we get what we pay for. But since you can get a virtual server with a dedicated public IP address as some server farm for as little as $5 to $10 US, it is generally less expensive to host any data or application in a data center (production, development, backup, storage, cloud) and use the "cheap dynamically allocated IP address server" for home where I do not keep to ping or access from outside my LAN.

Since we were discussing "Public ip is not shown in ifconfig - Ubuntu 16.04" and the original poster seeming does not understand basic IP addressing, routing and NAT, then it I think it is safe to assume that if they really need a public IP address then they need to pay for that service from the ISP. Also, in my view (maybe I am wrong) but if they had the skills to create scripts which watched for changing IP addresses on the public side and then updated all their services and mappings to keep it all in sync, they more likely would not be asking such as question and would have known the 192.168.0.0 address block was not publicly routable nor assigned by their ISP.

At least, that is how I read it.

Dear All,
Thank you for your explanatory posts.
I am totally sure that when I cancel my static ip service, I will never ever be able to ping my router remotely.
Normally I can detect the change of ip number when I am out of my network with small scripts but it will not work in my case as my ISP is eager to earn much more money with a greedy attitude.


Kind regards
Boris

I didn't follow the thread to its entirety, so can't tell where you got stuck, but if the approach using a dynamic DNS service doesn't work: I faintly remember to run a tiny cron job on my (internal) server checking for the router's WAN address, and, if changed, send out an e-mail with it. That wouldn't be something to satisfy customers' or public's needs, but it was enough to keep a path open for me to do remote maintenance.

@RudiC......Yes, that would work for you and me BUT it appears that the OP's ISP blocks in-bound traffic for subscribers in its public ip pool. So the ISP won't allow in-bound connections for non-static ip addresses. That seems to be why this issue has arisen.