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Updating DNS With Dynamic IP Addresses After a Router Reboot/Power Outage

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Updating DNS With Dynamic IP Addresses After a Router Reboot/Power Outage

About a year ago I wrote an article named Why I Cancelled my DynDNS Service and How I Replaced It with an IBM i Application.  

This article was how I wrote a few web service calls using GoDaddy APIs to check my current IP address and update them automatically if needed.  

Now that it is summer, thunderstorms are giving us power outages now and then.  While my IBM i and router are on a UPS (and also backed up with a generator) when the power flickers or goes out, it does cause a disconnect from our ISP which 99% of the time will result in an IP address refresh (yes, we're using a dynamic IP address... it's a long story).

What I noticed was while I was at home and this happened, even though I have a continuous job checking and updating my IP address ever couple hours I would need to go to my home office and call the program manually to get things reset so our website would still be available.  But what I also found is that I don't always have access to my office.  

So, because our local network is still available after a power outage, I wrote a small web service I can call from any PC, laptop or even mobile device to update our DNS from the comfort of where ever I happen to be. 

     H DFTACTGRP(*NO) BNDDIR('ERPGSDK')
      ****************************************************************
      * This is called CHECKDNSWS because if you call CHECKDNS it will try
      *  to call this program instead of the one in the GODADDY library.
      ****************************************************************
      ****************************************************************
      * Prototypes                                                   *
      ****************************************************************
      /COPY QCOPYSRC,P.ERPGSDK
      /COPY QCOPYSRC,P.LIBL
      *
     D CHECKDNS        PR                  EXTPGM
      ****************************************************************
     D i               S             10i 0
      ****************************************************************
      /free

       #pushlib('GODADDY');
       #pushlib('MAILTOOLBV');

       CHECKDNS();

       #poplib('GODADDY');
       #poplib('MAILTOOLBV');

       exsr $Return;
       //-------------------------------------------------------------/
       // Return                                                      /
       //-------------------------------------------------------------/
       begsr $Return;

         #startup();
         #writeTemplate('stdhtmlheader.erpg');
         #loadTemplate('message.erpg');
         #replaceData('/%msg%/':'CHECKDNS Called.');
         #writeSection();
         #cleanup();

         *INLR = *on;
         return;

       endsr;
      /end-free

So, as you can see, this program uses a GODADDY package that we created as well as the eRPG SDK.  We simply call the CHECKDNS program and return a message saying it has been called.  If the IP addresses are updated the IBM i sends an email and lets me know and things should be back to normal!  I simply made a bookmark that points to http://mylocalip/webservice/checkdns (which actually is routed to a program named CHECKDNSWS in my CGI library) and is available on any Chrome browser that I use, even my Pixel smartphone.

In fact, the program is so simple, I don't know why I didn't do this earlier, and all while not wearing a face covering!  Stay safe everyone!

 


Last edited 08/16/2020 at 12:00:28




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