HTTP headers sent by PHP - php

Question

I am using CURL and file_get_contents to find out the basic difference between a server request for a page and a browser request (organic).
I am requesting for a PHPINFO page both ways and found that it is giving different output in different cases.
For example, when I am using a browser the PHPINFO shows this:
_SERVER["HTTP_CACHE_CONTROL"] no-cache
This info is missing when I am requesting the same page through PHP.
My CURL:
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://www.example.com/phpinfo.php");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:32.0) Gecko/20100101 Firefox/32.0");
curl_setopt($ch, CURLOPT_INTERFACE, $testIP);
$output = curl_exec($ch);
curl_close($ch);
My file_get_contents:
$opts = array(
'socket' => array('bindto' => 'xxx.xx.xx.xx:0'),
'method' => 'GET',
'user_agent ' => "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:32.0) Gecko/20100101 Firefox/32.0", // this doesn't work
'header' => array('Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*\/*;q=0.8')
);
My goal:
To make a PHP request look identical to a browser request.

Answer 1

one of possible ways for server to detect you are a php code not a browser is check your cookie. with php curl request to the server once and inject the cookie you get to your next request.
check here :
http://docstore.mik.ua/orelly/webprog/pcook/ch11_04.htm
one other way that server can understand you are a robot(php code) is check referer http header.
you can learn more here :
http://en.wikipedia.org/wiki/HTTP_referer