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Detecting IPv6 Access to a Website

Tue, 01/20/2009 - 11:06 — marcelo

Yesterday I was in need of detecting when a web site or page is accessed via either IPv6 or IPv4. I wrote two rather simplistic PHP functions that so far seem to be up to the job. They just look for an ocurrence of the symbol ":" in the "REMOTE_ADDR" server variable. Here they are:

<?php
$ip = $_SERVER['REMOTE_ADDR'];
function is_ipv4($ip = "")
{
    if (substr_count($ip,":") > 0 && substr_count($ip,".") == 0){
        return false;
    } else {
        return true;
    }
}
return is_ipv4($ip);
?>
  
<?php
$ip = $_SERVER['REMOTE_ADDR'];
function is_ipv6($ip = "")
{
    if (substr_count($ip,":") > 0 && substr_count($ip,".") == 0){
        return true;
    } else {
        return false;
    }
}
return is_ipv6($ip);
?>

 Both functions can be used in Drupal to hide / show a block when accesed via IPv6 or IPv4.