Restriction based on IP ranges - php

Question

I am building an admin panel. and I want to block certain IP ranges. I'm testing this on my localhost wamp server but ir doesn't seem to redirect me.
<?php
if($_SERVER['REMOTE_ADDR'] == '127.0.0..*')
header("Location: http://google.com");
else
echo "Hai";
?>
Any input is appreciated.

Answer 1

Is sufficient to use string comparison
if (strncmp('127.0.0.', $_SERVER['REMOTE_ADDR'], 8) === 0)
header("Location: http://google.com");
else
echo "Hai";
Update: Taken from the comments of inits answer
Suppose i want to block any IP coming from this range: 192.168.0.1-255. What would be the best solution for it ? Thanks.
Then just make the same string comparison against this block
if (strncmp('192.168.0.', $_SERVER['REMOTE_ADDR'], 10) === 0)
header("Location: http://google.com");
else
echo "Hai";
If you want to test the remote address against both blocks at once, you will probably put them together into one expression. This time we need a different approach
if (in_array(substr($_SERVER['REMOTE_ADDR'], 0, strrpos($_SERVER['REMOTE_ADDR'], '.')), array('127.0.0', '192.168.0'))) {
header("Location: http://google.com");
else
echo "Hai";
The substr()-part takes the IP until the last .. We can just try to find this string in a set (-> array) of IP-prefixes.

Answer 2

$ip0 = ip2long("127.0.0.1");
$ip1 = ip2long("127.0.0.254");
$ip = ip2long($_SERVER['REMOTE_ADDR']);
if ($ip0 <= $ip && $ip <= $ip1) {
echo long2ip($ip) . " is inside range " . long2ip($ip0) . "-" . long2ip($ip1);
}
else {
echo long2ip($ip) . " is outside range " . long2ip($ip0) . "-" . long2ip($ip1);
}

Answer 3

This would be a better approach, using regualr expression:
// returns true for IPs 127.0.0.0-255
if (preg_match("'^127[.]0[.]0[.][0-9]+'",$_SERVER['REMOTE_ADDR']))
{
header("Location: http://google.com");
}
else
{
echo "Hai";
}
EDIT: Fine, take it to another level, maybe not the most effective, but easier to configure:
$mask = "192.168.1.1-255";
$ip = explode(".",$_SERVER['REMOTE_ADDR']);
$in = 0;
foreach (explode(".",$mask) as $k => $v)
{
if (preg_match("'^([0-9]+)-([0-9]+)$'",$v,$n))
{
if ($ip[$k] >= $n[1] && $ip[$k] <= $n[2]) $in++;
}
elseif (preg_match("'^[0-9]+$'",$v,$n))
{
if ($ip[$k] == $n[0]) $in++;
}
}
if ($in == 4)
{
header("Location: http://google.com");
}
else
{
echo "Hai";
}

Answer 4

Here is my solution to the problem of just allowing some fixed IPs and some IP ranges:
$ClientIP = $_SERVER['REMOTE_ADDR'];
$First3PartsOfIP = substr($ClientIP, 0, strrpos($ClientIP, '.'));
$AllowedIPs = ['127.0.0.1'];
$AllowedFirst3Parts = ['172.20.8', '172.21.13'];
if (!in_array($ClientIP, $AllowedIPs) && !in_array($First3PartsOfIP, $AllowedFirst3Parts)) {
//echo "Your IP: $ClientIP<br />";
die("Access Denied!");
}