PATH="/usr/local/sbin:/usr/local/bin:/bin:/sbin:/usr/bin:/usr/sbin"
export PATH
. need_root
iptables -L -n |
perl -ne '
	if (/^DROP\s+all\s+--\s+(\S+)\s+0\.0\.0\.0\/0\s*$/) {
		my $ip = $1;
		my $hostname = `ip_to_hostname $ip`;  # THIS SUCKS!
		chomp $hostname;
		print "$ip\t$hostname\n";
	}
'