<?php
$url = 'http://phpforum.ru/index.php?act=Login&CODE=01&Cookiedata=1';
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)");
curl_setopt($ch, CURLOPT_POST,1);
curl_setopt($ch, CURLOPT_POSTFIELDS,"UserName=login&PassWord=password&CookieDate=1&Privacy=1");
$html = curl_exec($ch);
echo $html;
curl_close($ch);
?>

$user_cookie_file = $_SERVER['DOCUMENT_ROOT'].'/cookies.txt';
curl_setopt($ch, CURLOPT_COOKIEFILE, $user_cookie_file);
curl_setopt($ch, CURLOPT_COOKIEJAR,  $user_cookie_file);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);

curl_setopt($ch, CURLOPT_COOKIESESSION, TRUE);

$url = "http://site.ru/index.php?act=Login&CODE=01";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$url); // set url to post to
curl_setopt($ch, CURLOPT_FAILONERROR, 1);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);// allow redirects
curl_setopt($ch, CURLOPT_COOKIESESSION, TRUE);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1); // return into a variable
curl_setopt($ch, CURLOPT_TIMEOUT, 50); // times out after 4s
curl_setopt($ch, CURLOPT_POST, 1); // set POST method
curl_setopt($ch, CURLOPT_POSTFIELDS, "url=LOGIN&refer=http://site.ru/&UserName=LOGIN&PassWord=PASS&CookieDate=1&submit=submit"); // add POST fields
curl_setopt ($ch, CURLOPT_COOKIEFILE, '1.txt'); // вроде откуда брать
curl_setopt ($ch, CURLOPT_COOKIEJAR, '1.txt'); // вроде куда сохранять
$result = curl_exec($ch); // run the whole process

preg_match_all('~Set-Cookie: ([^\r\n]*)[\r\n]~i',$result,$mass);
$all_cookie_string = implode(" ", $mass[1]);
curl_setopt($ch, CURLOPT_COOKIE, $all_cookie_string);
$url = "http://site.ru/index.php";
curl_setopt($ch, CURLOPT_URL,$url); // set url to post to
$result = curl_exec($ch);
curl_close($ch);