$text = '127.0.0.1';

if (preg_match('/^([0-9]|[0-9][0-9]|[01][0-9][0-9]|2[0-4][
0-9]|25[0-5])(\.([0-9]|[0-9][0-9]|[01][0-9][0-9]|2[0-4]
[0-9]|25[0-5])){3}$/', $text))
{
echo "Address is ok!"
}