DomainDog - Reverse Whois lookups from the CLI
For passive asset discovery, discovering domain names can be a valuable intelligence source. With the decline of Whois usage, reverse whois still lives on and can still be queried. DomainDog scrapes viewinfo so you can do lookups from your commandline - perfect for piping into aquatone for bug bounties or wide-scope blackbox penetration tests.
./dog.rb -s "firstname.lastname@example.org"
Easy as that!