This is not to promote hacking or fraud but Linux best suites security check or vulnerability test for your websites, network or organization. Here are top 10 Linux distributions available for penetration testing and can be downloaded freely. More tools can be installed if you wish to from respective repositories.

Source: http://gtbensmagazine.com/2018/06/19/top-10-best-linux-os-for-penetration-testing-security-or-hacking/