[Logician]

I'm not sure if it will work, but give it a try:

PHP Code:

$unregisteredhost=@gethostbyaddr($ipaddress);
if (strlen($unregisteredhost)>1  AND $postusername=='Unregistered')
{
$postusername=$unregisteredhost;
}
else if ($ipaddress AND $postusername=='Unregistered')
{
$postusername=$ipaddress;
}