php curl指定远端IP

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, '');
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Host: '));
$response = curl_exec($ch);
if (curl_errno($ch) != 0) {
    echo curl_error($ch);
} else {
    echo $response;
}
curl_close($ch);