Can servers block curl requests?

Question

I am working on ZOHO API and trying to update the record using cURL. I tried different cURL variations, but it always returns "false". But when I call the same URL using a browser, it works.

Is there any way they can block cURL requests? Is there any other way I can call that URL using a POST or maybe a GET request?

The cURL code I have tried is as below:

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HEADER, 0);
$data = curl_exec($ch);
curl_close($ch);

Answer 1

Many web servers want to block HTTP requests forged by something else than a browser, to prevent bots abuses. If you want to simulate/pretend your request from a browser, you at least have to:

1. Pass the exact same headers than your browsers (use ie Firebug to get them)

   curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
   

2. Change the user agent (name of the browser)

   curl_setopt($ch, CURLOPT_USERAGENT, $agent);
   

3. Enable cookies (for eg redirection and session handling)

   curl_setopt ($ch, CURLOPT_COOKIEJAR, $file);
   curl_setopt ($ch, CURLOPT_RETURNTRANSFER, true);
   

4. Add referers

   curl_setopt($curl, CURLOPT_REFERER, 'http://www.google.com');
   curl_setopt($curl, CURLOPT_AUTOREFERER, true);
   

And pray you haven't missed anything!