<?php

function iptonumber($ip)
{
    if ($ip == '') {
        return 0;
    } else {
        $ips = split ('\.', $ip);
        return ($ips[3] + $ips[2] * 256 + $ips[1] * 256 * 256 + $ips[0] * 256 * 256 * 256);
    }
}
//low end of the range to block
$low = iptonumber('1.101.11.111');

//high end of the range to block
$high = iptonumber('1.101.11.11');

$ip = $_SERVER['REMOTE_ADDR'];

$ip = iptonumber($ip);

if($ip >= $low && $ip <= $high){

header('Location: http://domain.com');
}
?>