:small_orange_diamond: <ahref="https://midnight-commander.org/"><b>Midnight Commander</b></a> - visual file manager, licensed under GNU General Public License.<br>
:small_orange_diamond: <ahref="https://www.gnu.org/software/screen/"><b>screen</b></a> - full-screen window manager that multiplexes a physical terminal.<br>
:small_orange_diamond: <ahref="https://github.com/tmux/tmux/wiki"><b>tmux</b></a> - terminal multiplexer, lets you switch easily between several programs in one terminal.<br>
:small_orange_diamond: <ahref="https://gnutls.org/manual/html_node/gnutls_002dcli-Invocation.html"><b>gnutls-cli</b></a> - client program to set up a TLS connection to some other computer.<br>
:small_orange_diamond: <ahref="http://netcat.sourceforge.net/"><b>netcat</b></a> - networking utility which reads and writes data across network connections, using the TCP/IP protocol.<br>
:small_orange_diamond: <ahref="https://github.com/dbcli/pgcli"><b>pgcli</b></a> - postgres CLI with autocompletion and syntax highlighting.<br>
:small_orange_diamond: <ahref="https://www.ssllabs.com/ssltest/"><b>SSL Server Test</b></a> - free online service performs a deep analysis of the configuration of any SSL web server.<br>
:small_orange_diamond: <ahref="https://dev.ssllabs.com/ssltest/"><b>SSL Server Test (DEV)</b></a> - free online service performs a deep analysis of the configuration of any SSL web server.<br>
:small_orange_diamond: <ahref="https://www.htbridge.com/ssl/"><b>ImmuniWebĀ® SSLScan</b></a> - test SSL/TLS (PCI DSS, HIPAA and NIST).<br>
:small_orange_diamond: <ahref="https://report-uri.com/home/tools"><b>Report URI</b></a> - monitoring security policies like CSP and HPKP.<br>
:small_orange_diamond: <ahref="https://csp-evaluator.withgoogle.com/"><b>CSP Evaluator</b></a> - allows developers and security experts to check if a Content Security Policy.<br>
:small_orange_diamond: <ahref="https://ccadb.org/resources"><b>Common CA Database</b></a> - repository of information about CAs, and their root and intermediate certificates.<br>
:small_orange_diamond: <ahref="https://securityheaders.com/"><b>Security Headers</b></a> - analyse the HTTP response headers (with rating system to the results).<br>
:small_orange_diamond: <ahref="https://observatory.mozilla.org/"><b>Observatory by Mozilla</b></a> - set of tools to analyze your website.<br>
:small_orange_diamond: <ahref="https://mxtoolbox.com/SuperTool.aspx"><b>MX Toolbox</b></a> - all of your MX record, DNS, blacklist and SMTP diagnostics in one integrated tool.<br>
:small_orange_diamond: <ahref="https://censys.io/"><b>Censys</b></a> - platform that helps information security practitioners discover, monitor, and analyze devices.<br>
:small_orange_diamond: <ahref="https://www.shodan.io/"><b>Shodan</b></a> - the world's first search engine for Internet-connected devices.<br>
:small_orange_diamond: <ahref="https://toolbar.netcraft.com/site_report"><b>Netcraft</b></a> - detailed report about the site, helping you to make informed choices about their integrity.<br>
:small_orange_diamond: <ahref="https://www.url-encode-decode.com/"><b>URL Encode/Decode</b></a> - tool from above to either encode or decode a string of text.<br>
:small_orange_diamond: <ahref="https://www.random.org/passwords/"><b>Random.org</b></a> - generate random passwords.<br>
:small_orange_diamond: <ahref="https://gotcha.pw/"><b>Gotcha?</b></a> - list of 1.4 billion accounts circulates around the Internet.<br>
:small_orange_diamond: <ahref="https://haveibeenpwned.com/"><b>have i been pwned?</b></a> - check if you have an account that has been compromised in a data breach.<br>
:small_orange_diamond: <ahref="https://github.com/dylanaraps/pure-bash-bible"><b>pure-bash-bible</b></a> - a collection of pure bash alternatives to external processes.<br>
:small_orange_diamond: <ahref="http://wiki.bash-hackers.org/start"><b>The Bash Hackers Wiki</b></a> - hold documentation of any kind about GNU Bash.<br>
:small_orange_diamond: <ahref="https://www.cyberciti.biz/"><b>nixCraft</b></a> - linux and unix tutorials for new and seasoned sysadmin.<br>
:small_orange_diamond: <ahref="http://www.brendangregg.com/"><b>Brendan Gregg's Blog</b></a> - Brendan Gregg is an industry expert in computing performance and cloud computing.<br>
:small_orange_diamond: <ahref="http://gynvael.coldwind.pl/"><b>Gynvael "GynDream" Coldwind</b></a> - Gynvael is a IT security engineer at Google.<br>
:small_orange_diamond: <ahref="https://ma.ttias.be/"><b>Mattias Geniar</b></a> - developer, Sysadmin, Blogger, Podcaster and Public Speaker.<br>
:small_orange_diamond: <ahref="https://nickcraver.com/"><b>Nick Craver</b></a> - Software Developer and Systems Administrator for Stack Exchange.<br>
:small_orange_diamond: <ahref="https://robert.penz.name/"><b>Robert Penz</b></a> - IT security Expert.<br>
:small_orange_diamond: <ahref="https://scotthelme.co.uk/"><b>Scott Helme</b></a> - Security Researcher, international speaker and founder of securityheaders.com and report-uri.com.<br>
:small_orange_diamond: <ahref="https://security.szurek.pl/"><b>Kacper Szurek</b></a> - Detection Engineer at ESET.<br>
:small_orange_diamond: <ahref="https://www.troyhunt.com/"><b>Troy Hunt</b></a> - Microsoft Regional Director and Microsoft Most Valuable Professional for Developer Security.<br>
:small_orange_diamond: <ahref="https://varnish-cache.org/"><b>Varnish HTTP Cache</b></a> - HTTP accelerator designed for content-heavy dynamic web sites.<br>
:small_orange_diamond: <ahref="https://emeraldonion.org/"><b>Emerald Onion</b></a> - Seattle-based encrypted-transit internet service provider.<br>
:small_orange_diamond: <ahref="https://www.commandlinefu.com/commands/browse"><b>commandlinefu.com</b></a> - command line diamonds, created and voted on by our members.<br>
:small_orange_diamond: <ahref="https://www.openbugbounty.org/"><b>Openbugbounty</b></a> - allows any security researcher reporting a vulnerability on any website.<br>
:small_orange_diamond: <ahref="https://www.hackerone.com/"><b>hackerone</b></a> - global hacker community to surface the most relevant security issues.<br>
:small_orange_diamond: <ahref="https://www.bugcrowd.com/"><b>bugcrowd</b></a> - crowdsourced cybersecurity for the enterprise.<br>
:small_orange_diamond: <ahref="https://www.owasp.org/index.php/OWASP_Juice_Shop_Project"><b>OWASP Juice Shop Project</b></a> - the most bug-free vulnerable application in existence.<br>
:small_orange_diamond: <ahref="https://www.owasp.org/index.php/Category:OWASP_WebGoat_Project"><b>OWASP WebGoat Project</b></a> - insecure web application maintained by OWASP designed to teach web app security.<br>
:small_orange_diamond: <ahref="https://github.com/opendns/Security_Ninjas_AppSec_Training"><b>Security Ninjas</b></a> - open source application security training program.<br>