Simple DNS Lookup – Simple DNS Lookup for a domain to find out MX Record information / A Record information and server details.
What Is My IP – This is a simple tool to find your public IP Address
Who Is – Simple tool to find out who and where a domain is hosted
SSL Cert Checker – This is a great tool to check if a cert is valid and has a proper chain of ownership. Using this tool to make sure a cert chain is legit is very important.
SSL FingerPrint Checker – Great took to make sure a cert fingerprint is legit and real.
Networking Assistant – Free Password Generator and Subnet Calculator
Nmap – Free Security Scanner, Port Scanner, & Network Exploration Tool
Angry IP Scanner – The original IP scanner for Windows, Mac, and Linux. Fast, friendly, extensible, free and open-source. Scans addresses and ports in any range and exports.
Metasploit – A collaboration between the open-source community and Rapid7. Metasploit Framework is free.
Wireshark – Wireshark is a free and open-source packet analyzer.
Crackstation – CrackStation uses massive pre-computed lookup tables to crack password hashes. (see how strong your password is)
SQRL – Free replacement for usernames, passwords, reminders, one-time-code authenticators . . . and everything else.
Free TFTP Server – Easily push OS images, firmware, and configuration updates, backup configuration files, and transfer files up to 4GB.