re: How to send a simple message to an IP Address or MAC Add

we have the same concern. I also need to send a message to a mac. ip address but to tell them where to buy wifi credit in order to access the internet. I have a wifi business, PIN code base, users at 500 meters can connect but they can only connect upto the portal where they can enter the wifi credit pid code.

Have you already gotten a software for that? can you share it to me?