domínio

http://serverfault.com/questions/398535/iptables-rule-to-block-all-web-…

http://blog.nintechnet.com/how-to-block-w00tw00t-at-isc-sans-dfind-and-…

dig @8.8.8.8 _spf.google.com txt

dig @8.8.8.8 _netblocks.google.com txt