Checking IP's against spammer database

[Jeff]

There is a good free RBL that checks users against a database of known forum spammers. You can check a users IP against it before allowing them to do anything on your site. Here is some example PHP code:

function blacklisted($ip) 
{
    $dnsbl_check=array("dnsbl.tornevall.org");

    if($ip){
        $rip=implode('.',array_reverse(explode(".",$ip)));
        foreach($dnsbl_check as $val){
            if(checkdnsrr($rip.'.'.$val.'.','A'))
                return $rip.'.'.$val;
        }
    }

    return false;
}

Basically just pass the IP to this function and if it comes back as true, then the IP is listed.

Enjoy!