Having email addresses belonging to the target system/organization can prove to be useful during further phases of penetration testing. theHarvester helps us gather various email addresses belonging to our target system/organization. It uses various online sources for gathering this information. The following screenshot shows various parameters of theHarvester:

root@kali:~# theharvester -d demo.testfire.net -l 20 -b google -h output.html

The preceding syntax would execute theharvester on the domain demo.testfire.net and look for up to 20 email IDs using Google as the search engine and then store the output in the output.html file.