If multiple users are behind the same firewall they will share the external IP address of that firewall.
So it can be that multiple users share the same IP address.
How about adding a unique ID for each user in the database that saves the user credentials?
The unique ID would be used to identify the user + password combination.
Very good point!
I intend to have a database, and each user will have a unique ID. But when you enter a program cold it has no idea who you are and has no way to identify you other than the IP address. If the user clicks on a link that takes them to another program, there either has to be a way to pass an identifier to that new program or else they have to log in again on the new page. If I can pass just a username then I can use that user name to look them up in the database and get whatever information I had them enter at registration and any permissions they may be granted on the site. But if I can't pass anything from one program to the next the database does no good in this case. You could put the users IP address into the database, but IP addresses are not always static, especially with cell phones. Plus if their name starts with a Z you would have to read through the entire database before you would find it, slowing down your web page.
How can the program tell who just came online on the page (other than their IP address) unless there's a way to pass some kind of identifier to that program?
I see your point about multiple people sharing the IP address. I'm sure my wife and I both have the same IP address because we're both using the same router. Maybe I just have to design my site around having to sign in every time you want to post something. And hopefully in the future Carl will be able to add the CommandLine$ function which is really all you would need for this kind of thing. That would be the perfect command for this because it's already part of most of the popular BASIC dialects.
The only time my users will need credentials is when they're posting something to the site. In the mean time they'll just have to get used to doing all their posting in one session and then surfing the site without their credentials. If they wanted to send someone a message or something they would just have to log in again. I'm not crazy about it, but this I can work around.