- Always do your work on special dedicated machine or virtualization environment and don't forget about VPN!
- Don't hack the systems or applications without explicit permission. Except Russia.- Kali Linux - Kali Linux. Special OS for offensive security specialists.
- Parrot Security - Parrot Security OS.OS for security specialists.
- Tails – Live OS aimed at preserving privacy and anonymity.
- ArchStrike – Arch GNU/Linux repository for security professionals and enthusiasts.
- BlackArch – Arch GNU/Linux-based distribution with best Hacking Tools for penetration testers and security researchers.
- Network Security Toolkit – Fedora-based bootable live operating system designed to provide easy access to best-of-breed open source network security applications.
- Pentoo – Security-focused live CD based on Gentoo.
- BackBox – Ubuntu-based distribution for penetration tests and security assessments.
- Fedora Security Labs – Provides a safe test environment to work on security auditing, forensics, system rescue and teaching security testing methodologies.
- AttifyOS – GNU/Linux distribution focused on tools useful during Internet of Things (IoT) security assessments.
- https://book.hacktricks.xyz/ - site for hacking tricks and articles.
- https://tryhackme.com/dashboard - some free trainings and skill improving environment.
- https://www.hackthebox.com/ - huge site for trainings.
- https://github.com/cytopia/docker-dvwa - docker-based training box.
- https://www.torproject.org/ - secure and anonymous web browser.