Environmental variables in Perl

I would like to grab a visitors IP and hostname (for security purposes) from a HTML form and write it to a file within a perl script.

I've sorted the writing to the file bit but just cannot get the ip or hostname.

$ip = $ENV{'REMOTE_ADDR'};
$n = `nslookup $ip | grep Name`; chop($n);
$host = substr($n, rindex($n, " ")+1);

if ($host eq "") {
$host=$ENV{'REMOTE_ADDR'};
}

$ip is the IP address and $host is the Host address. If $ip cannot resolve to $host, $host = $ip so $host won't give you a blank value.