theHarvester is a command-line tool included in Kali Linux that acts as a wrapper for a variety of search engines and is used to find email accounts, subdomain names, virtual hosts, open ports / banners, and employee names related to a domain from different public sources (such as search engines and PGP key servers). In recent versions, the authors added the capability of doing DNS brute force, reverse IP resolution, and Top-Level Domain (TLD) expansion.
In the following example, theharvester is used to gather information about zonetransfer.me:
