Frames without frames. AJAH selective insertion

And W3C said Let there be frames, and there was frames, and they were used (and abused) and it was good, and W3C said This is right (we're gonna deprecate them soon) and there was much rejoicing.

Is not new that web developers hate all that's made with frames. They're a burden nobody wants to carry, so confusing, so "nineties", so... well, deprecated, that's it. So you may think I'm just delving into the past. Frames, as we know it, are dissapearing into extinction but, the main idea, more or less, is still needed nowadays.

Real IP Problem and X-Forwarded-For header

Someone has been in a situation like this? I bet it

• We need a way to know whether a user is logged in or not.
• Easy as pie. Go on sessions with him.
• We can't rely on the user's browser to allow cookies.
• Well, we rely on the user's browser to have JavaScript, so why...?
• I said no cookies. Use the IP address.