I've read a lot about .htaccess rules, checking headers, using encryption etc.. but I haven't found exactly the answer I'm after. I know that assuming the server is set up right, you can't access my precious PHP scripts with AJAX. I tried checking if an access variable was defined which disallowed address bar access but also blocked my AJAX requests.
If I have some PHP scripts that I use for AJAX calls, is there a way that I can prevent address bar access, PHP POST (cURL etc) as well as AJAX from outside my domain (assumed via cross-domain access restrictions) ?
There is NO way absolutely to safely/reliably identify which part of the browser the request comes from -- address bar, AJAX. There's a way to identify what is sending though browser/curl/etc via User-Agent header (but not reliably)
A quick but a lot less reliable solution would be to check for the following header. Most browsers attach it with AJAX calls. Be sure to thoroughly look into it, and implement.
NOTE: Do not trust the client if the resource is cruicial. You are better off implementing some other means of access filtering. Remember, any one can fake headers!