<form action="1.php" method="post">
<input type="submit" name='submit' value='submit' />
</form>
<?php
$url = 'http://abc.com/';

$post_fields = 'action=add&post=123';
$reffer = 'http://abc.com/';
$agent = 'Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/20100101 Firefox/17.0';

$ch = curl_init();
curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookie.txt');
curl_setopt($ch, CURLOPT_COOKIEFILE, "cookie.txt";
curl_setopt($ch, CURLOPT_REFERER, $reffer);
curl_setopt($ch, CURLOPT_USERAGENT, $agent);
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

curl_exec($ch);
if($_POST['submit'])
{
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_REFERER, $reffer);
curl_setopt($ch, CURLOPT_USERAGENT, $agent);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_fields);
$result = curl_exec($ch);
curl_close($ch);

echo $result;
}
?>