"Knowledge is powerful, be careful how you use it!"

This repository is a collection of various materials and tools that I use every day in my work. It contains a lot of useful information gathered in one piece. It is an invaluable source of knowledge for me that I often look back on.

For everyone, really. Here everyone can find their favourite tastes. But to be perfectly honest, it is aimed towards System and Network administrators, DevOps, Pentesters, and Security Researchers.

If you find something which doesn't make sense, or something doesn't seem right, please make a pull request and please add valid and well-reasoned explanations about your changes or comments.

A few simple rules for this project:

• inviting and clear
• not tiring
• useful

These below rules may be better:

• easy to contribute to (Markdown + HTML ...)
• easy to find (simple TOC, maybe it's worth extending them?)

Url marked * is temporary unavailable. Please don't delete it without confirming that it has permanently expired.

Before adding a pull request, please see the contributing guidelines. You should also remember about this:

+ This repository is not meant to contain everything but only good quality stuff.

All suggestions/PR are welcome!

This project exists thanks to all the people who contribute.

GitHub exposes an RSS/Atom feed of the commits, which may also be useful if you want to be kept informed about all changes.

• Add new stuff...
• Add useful shell functions
• Add one-liners for collection tools (eg. CLI Tools)
• Sort order in lists

New items are also added on a regular basis.

Only main chapters:

• CLI Tools
• GUI Tools
• Web Tools
• Systems/Services
• Networks
• Containers/Orchestration
• Manuals/Howtos/Tutorials
• Inspiring Lists
• Blogs/Podcasts/Videos
• Hacking/Penetration Testing
• Your daily knowledge and news
• Other Cheat Sheets
• Shell One-liners
• Shell Tricks
• Shell Functions

   GNU Bash - is an sh-compatible shell that incorporates useful features from the Korn shell and C shell.
   Zsh - is a shell designed for interactive use, although it is also a powerful scripting language.
   tclsh - is a very powerful cross-platform shell, suitable for a huge range of uses.
   bash-it - is a framework for using, developing and maintaining shell scripts and custom commands.
   Oh My ZSH! - is the best framework for managing your Zsh configuration.
   Oh My Fish - the Fishshell framework.
   Starship - the cross-shell prompt written in Rust.
   powerlevel10k - is a fast reimplementation of Powerlevel9k ZSH theme.

   z - tracks the folder you use the most and allow you to jump, without having to type the whole path.
   fzf - is a general-purpose command-line fuzzy finder.
   zsh-autosuggestions - Fish-like autosuggestions for Zsh.
   zsh-syntax-highlighting - Fish shell like syntax highlighting for Zsh.
   Awesome ZSH Plugins - A list of frameworks, plugins, themes and tutorials for ZSH.

   Midnight Commander - is a visual file manager, licensed under GNU General Public License.
   ranger - is a VIM-inspired filemanager for the console.
   nnn - is a tiny, lightning fast, feature-packed file manager.
   screen - is a full-screen window manager that multiplexes a physical terminal.
   tmux - is a terminal multiplexer, lets you switch easily between several programs in one terminal.
   tmux-cssh - is a tool to set comfortable and easy to use functionality tmux-sessions.

   vi - is one of the most common text editors on Unix.
   vim - is a highly configurable text editor.
   emacs - is an extensible, customizable, free/libre text editor, and more.
   micro - is a modern and intuitive terminal-based text editor.
   neovim - is a free open source, powerful, extensible and usable code editor.
   spacemacs - a community-driven Emacs distribution.
   spacevim - a community-driven vim distribution.

   fd - is a simple, fast and user-friendly alternative to find.
   ncdu - is an easy to use, fast disk usage analyzer.

   PuTTY - is an SSH and telnet client, developed originally by Simon Tatham.
   Mosh - is a SSH wrapper designed to keep a SSH session alive over a volatile connection.
   Eternal Terminal - enables mouse-scrolling and tmux commands inside the SSH session.
   nmap - is a free and open source (license) utility for network discovery and security auditing.
   zmap - is a fast single packet network scanner designed for Internet-wide network surveys.
   Rust Scan - to find all open ports faster than Nmap.
   masscan - is the fastest Internet port scanner, spews SYN packets asynchronously.
   pbscan - is a faster and more efficient stateless SYN scanner and banner grabber.
   hping - is a command-line oriented TCP/IP packet assembler/analyzer.
   mtr - is a tool that combines the functionality of the 'traceroute' and 'ping' programs in a single tool.
   mylg - utility which combines the functions of the different network probes in one diagnostic tool.
   netcat - utility which reads and writes data across network connections, using the TCP/IP protocol.
   socat - utility which transfers data between two objects.
   tcpdump - is a powerful command-line packet analyzer.
   tshark - is a tool that allows us to dump and analyze network traffic (wireshark cli).
   Termshark - is a simple terminal user-interface for tshark.
   ngrep - is like GNU grep applied to the network layer.
   netsniff-ng - is a Swiss army knife for your daily Linux network plumbing if you will.
   sockdump - dump unix domain socket traffic.
   stenographer - is a packet capture solution which aims to quickly spool all packets to disk.
   tcpterm - visualize packets in TUI.
   bmon - is a monitoring and debugging tool to capture networking related statistics and prepare them visually.
   iptraf-ng - is a console-based network monitoring program for Linux that displays information about IP traffic.
   vnstat - is a network traffic monitor for Linux and BSD.
   iPerf3 - is a tool for active measurements of the maximum achievable bandwidth on IP networks.
   ethr - is a Network Performance Measurement Tool for TCP, UDP & HTTP.
   Etherate - is a Linux CLI based Ethernet and MPLS traffic testing tool.
   echoip - is a IP address lookup service.
   Nemesis - packet manipulation CLI tool; craft and inject packets of several protocols.
   packetfu - a mid-level packet manipulation library for Ruby.
   Scapy - packet manipulation library; forge, send, decode, capture packets of a wide number of protocols.
   impacket - is a collection of Python classes for working with network protocols.
   ssh-audit - is a tool for SSH server auditing.
   aria2 - is a lightweight multi-protocol & multi-source command-line download utility.
   iptables-tracer - observe the path of packets through the iptables chains.
   inception - a highly configurable tool to check for whatever you like against any number of hosts.
   mRemoteNG - a fork of mRemote, multi-tabbed PuTTy on steroids!

   dnsdiag - is a DNS diagnostics and performance measurement tools.
   fierce - is a DNS reconnaissance tool for locating non-contiguous IP space.
   subfinder - is a subdomain discovery tool that discovers valid subdomains for websites.
   sublist3r - is a fast subdomains enumeration tool for penetration testers.
   amass - is tool that obtains subdomain names by scraping data sources, crawling web archives, and more.
   namebench - provides personalized DNS server recommendations based on your browsing history.
   massdns - is a high-performance DNS stub resolver for bulk lookups and reconnaissance.
   knock - is a tool to enumerate subdomains on a target domain through a wordlist.
   dnsperf - DNS performance testing tools.
   dnscrypt-proxy 2 - a flexible DNS proxy, with support for encrypted DNS protocols.
   dnsdbq - API client providing access to passive DNS database systems.
   grimd - fast dns proxy, built to black-hole internet advertisements and malware servers.
   dnstwist - detect typosquatters, phishing attacks, fraud, and brand impersonation.

   curl - is a command line tool and library for transferring data with URLs.
   kurly - is an alternative to the widely popular curl program, written in Golang.
   HTTPie - is an user-friendly HTTP client.
   wuzz - is an interactive cli tool for HTTP inspection.
   h2spec - is a conformance testing tool for HTTP/2 implementation.
   h2t - is a simple tool to help sysadmins to hardening their websites.
   htrace.sh - is a simple Swiss Army knife for http/https troubleshooting and profiling.
   httpstat - is a tool that visualizes curl statistics in a way of beauty and clarity.
   httplab - is an interactive web server.
   Lynx - is a text browser for the World Wide Web.
   Browsh - is a fully interactive, real-time, and modern text-based browser.
   HeadlessBrowsers - a list of (almost) all headless web browsers in existence.
   ab - is a single-threaded command line tool for measuring the performance of HTTP web servers.
   siege - is an http load testing and benchmarking utility.
   wrk - is a modern HTTP benchmarking tool capable of generating significant load.
   wrk2 - is a constant throughput, correct latency recording variant of wrk.
   vegeta - is a constant throughput, correct latency recording variant of wrk.
   bombardier - is a fast cross-platform HTTP benchmarking tool written in Go.
   gobench - http/https load testing and benchmarking tool.
   hey - HTTP load generator, ApacheBench (ab) replacement, formerly known as rakyll/boom.
   boom - is a script you can use to quickly smoke-test your web app deployment.
   SlowHTTPTest - is a tool that simulates some Application Layer Denial of Service attacks by prolonging HTTP.
   gobuster - is a free and open source directory/file & DNS busting tool written in Go.
   ssllabs-scan - command-line reference-implementation client for SSL Labs APIs.
   http-observatory - Mozilla HTTP Observatory cli version.
   Hurl - is a command line tool to run and test HTTP requests with plain text.

   openssl - is a robust, commercial-grade, and full-featured toolkit for the TLS and SSL protocols.
   gnutls-cli - client program to set up a TLS connection to some other computer.
   sslyze - fast and powerful SSL/TLS server scanning library.
   sslscan - tests SSL/TLS enabled services to discover supported cipher suites.
   testssl.sh - testing TLS/SSL encryption anywhere on any port.
   cipherscan - a very simple way to find out which SSL ciphersuites are supported by a target.
   spiped - is a utility for creating symmetrically encrypted and authenticated pipes between socket addresses.
   Certbot - is EFF's tool to obtain certs from Let's Encrypt and (optionally) auto-enable HTTPS on your server.
   mkcert - simple zero-config tool to make locally trusted development certificates with any names you'd like.
   certstrap - tools to bootstrap CAs, certificate requests, and signed certificates.
   Sublert - is a security and reconnaissance tool to automatically monitor new subdomains.
   mkchain - open source tool to help you build a valid SSL certificate chain.
   ssl-cert-check - SSL Certification Expiration Checker.

   SELinux - provides a flexible Mandatory Access Control (MAC) system built into the Linux kernel.
   AppArmor - proactively protects the operating system and applications from external or internal threats.
   grapheneX - Automated System Hardening Framework.
   DevSec Hardening Framework - Security + DevOps: Automatic Server Hardening.

   ossec - actively monitoring all aspects of system activity with file integrity monitoring.
   auditd - provides a way to track security-relevant information on your system.
   Tiger - is a security tool that can be use both as a security audit and intrusion detection system.
   Lynis - battle-tested security tool for systems running Linux, macOS, or Unix-based operating system.
   LinEnum - scripted Local Linux Enumeration & Privilege Escalation Checks.
   Rkhunter - scanner tool for Linux systems that scans backdoors, rootkits and local exploits on your systems.
   PE-sieve - is a light-weight tool that helps to detect malware running on the system.
   PEASS - privilege escalation tools for Windows and Linux/Unix and MacOS.

   strace - diagnostic, debugging and instructional userspace utility for Linux.
   DTrace - is a performance analysis and troubleshooting tool.
   ltrace - is a library call tracer, used to trace calls made by programs to library functions.
   ptrace-burrito - is a friendly wrapper around ptrace.
   perf-tools - performance analysis tools based on Linux perf_events (aka perf) and ftrace.
   bpftrace - high-level tracing language for Linux eBPF.
   sysdig - system exploration and troubleshooting tool with first class support for containers.
   Valgrind - is an instrumentation framework for building dynamic analysis tools.
   gperftools - high-performance multi-threaded malloc() implementation, plus some performance analysis tools.
   glances - cross-platform system monitoring tool written in Python.
   htop - interactive text-mode process viewer for Unix systems. It aims to be a better 'top'.
   bashtop - Linux resource monitor written in pure Bash.
   nmon - a single executable for performance monitoring and data analysis.
   atop - ASCII performance monitor. Includes statistics for CPU, memory, disk, swap, network, and processes.
   lsof - displays in its output information about files that are opened by processes.
   FlameGraph - stack trace visualizer.
   lsofgraph - convert Unix lsof output to a graph showing FIFO and UNIX interprocess communication.
   rr - is a lightweight tool for recording, replaying and debugging execution of applications.
   Performance Co-Pilot - a system performance analysis toolkit.
   hexyl - a command-line hex viewer.
   Austin - Python frame stack sampler for CPython.

   angle-grinder - slice and dice log files on the command line.
   lnav - log file navigator with search and automatic refresh.
   GoAccess - real-time web log analyzer and interactive viewer that runs in a terminal.
   ngxtop - real-time metrics for nginx server.

   usql - universal command-line interface for SQL databases.
   pgcli - postgres CLI with autocompletion and syntax highlighting.
   mycli - terminal client for MySQL with autocompletion and syntax highlighting.
   litecli - SQLite CLI with autocompletion and syntax highlighting.
   mssql-cli - SQL Server CLI with autocompletion and syntax highlighting.
   OSQuery - is a SQL powered operating system instrumentation, monitoring, and analytics framework.
   pgsync - sync data from one Postgres database to another.
   iredis - a terminal client for redis with autocompletion and syntax highlighting.
   SchemaCrawler - generates an E-R diagram of your database.

   Nipe - script to make Tor Network your default gateway.
   multitor - a tool that lets you create multiple TOR instances with a load-balancing.

   Irssi - is a free open source terminal based IRC client.
   WeeChat - is an extremely extensible and lightweight IRC client.

   taskwarrior - task management system, todo list

   sysadmin-util - tools for Linux/Unix sysadmins.
   incron - is an inode-based filesystem notification technology.
   lsyncd - synchronizes local directories with remote targets (Live Syncing Daemon).
   GRV - is a terminal based interface for viewing Git repositories.
   Tig - text-mode interface for Git.
   tldr - simplified and community-driven man pages.
   archiver - easily create and extract .zip, .tar, .tar.gz, .tar.bz2, .tar.xz, .tar.lz4, .tar.sz, and .rar.
   commander.js - minimal CLI creator in JavaScript.
   gron - make JSON greppable!
   bed - binary editor written in Go.

   Guake - is a dropdown terminal made for the GNOME desktop environment.
   Terminator - is based on GNOME Terminal, useful features for sysadmins and other users.
   Kitty - is a GPU based terminal emulator that supports smooth scrolling and images.
   Alacritty - is a fast, cross-platform, OpenGL terminal emulator.

   Wireshark - is the world’s foremost and widely-used network protocol analyzer.
   Ettercap - is a comprehensive network monitor tool.
   EtherApe - is a graphical network monitoring solution.
   Packet Sender - is a networking utility for packet generation and built-in UDP/TCP/SSL client and servers.
   Ostinato - is a packet crafter and traffic generator.
   JMeter™ - open source software to load test functional behavior and measure performance.
   locust - scalable user load testing tool written in Python.

   TOR Browser - protect your privacy and defend yourself against network surveillance and traffic analysis.

   KeePassXC - store your passwords safely and auto-type them into your everyday websites and apps.
   Bitwarden - open source password manager with built-in sync.
   Vaultwarden - unofficial Bitwarden compatible server written in Rust.

   HexChat - is an IRC client based on XChat.
   Pidgin - is an easy to use and free chat client used by millions.

   Signal - is an encrypted communications app.
   Wire - secure messaging, file sharing, voice calls and video conferences.
   TorChat - decentralized anonymous instant messenger on top of Tor Hidden Services.
   Matrix - an open network for secure, decentralized, real-time communication.

   Sublime Text - is a lightweight, cross-platform code editor known for its speed, ease of use.
   Visual Studio Code - an open-source and free source code editor developed by Microsoft.
   Atom - a hackable text editor for the 21st Century.

   SSL/TLS Capabilities of Your Browser - test your browser's SSL implementation.
   Can I use - provides up-to-date browser support tables for support of front-end web technologies.
   Panopticlick 3.0 - is your browser safe against tracking?
   Privacy Analyzer - see what data is exposed from your browser.
   Web Browser Security - it's all about Web Browser fingerprinting.
   How's My SSL? - help a web server developer learn what real world TLS clients were capable of.
   sslClientInfo - client test (incl TLSv1.3 information).

   SSLLabs Server Test - performs a deep analysis of the configuration of any SSL web server.
   SSLLabs Server Test (DEV) - performs a deep analysis of the configuration of any SSL web server.
   ImmuniWeb® SSLScan - test SSL/TLS (PCI DSS, HIPAA and NIST).
   SSL Check - scan your website for non-secure content.
   SSL Scanner - analyze website security.
   CryptCheck - test your TLS server configuration (e.g. ciphers).
   urlscan.io - service to scan and analyse websites.
   Report URI - monitoring security policies like CSP and HPKP.
   CSP Evaluator - allows developers and security experts to check if a Content Security Policy.
   Useless CSP - public list about CSP in some big players (might make them care a bit more).
   Why No HTTPS? - top 100 websites by Alexa rank not automatically redirecting insecure requests.
   TLS Cipher Suite Search- cipher suite search engine.
   cipherli.st - strong ciphers for Apache, Nginx, Lighttpd, and more.*
   dhtool - public Diffie-Hellman parameter service/tool.
   badssl.com - memorable site for testing clients against bad SSL configs.
   tlsfun.de - registered for various tests regarding the TLS/SSL protocol.
   CAA Record Helper - generate a CAA policy.
   Common CA Database - repository of information about CAs, and their root and intermediate certificates.
   CERTSTREAM - real-time certificate transparency log update stream.
   crt.sh - discovers certificates by continually monitoring all of the publicly known CT.
   Hardenize - deploy the security standards.
   Cipher suite compatibility - test TLS cipher suite compatibility.
   urlvoid - this service helps you detect potentially malicious websites.
   security.txt - a proposed standard (generator) which allows websites to define security policies.
   ssl-config-generator - help you follow the Mozilla Server Side TLS configuration guidelines.
   TLScan - pure python, SSL/TLS protocol and cipher scanner/enumerator.

   Security Headers - analyse the HTTP response headers (with rating system to the results).
   Observatory by Mozilla - set of tools to analyze your website.
   webhint - is a linting tool that will help you with your site's accessibility, speed, security, and more.

   ViewDNS - one source for free DNS related tools and information.
   DNSLookup - is an advanced DNS lookup tool.
   DNSlytics - online DNS investigation tool.
   DNS Spy - monitor, validate and verify your DNS configurations.
   Zonemaster - helps you to control how your DNS works.
   Leaf DNS - comprehensive DNS tester.
   Find subdomains online - find subdomains for security assessment penetration test.
   DNSdumpster - dns recon & research, find & lookup dns records.
   DNS Table online - search for DNS records by domain, IP, CIDR, ISP.
   intoDNS - DNS and mail server health checker.
   DNS Bajaj - check the delegation of your domain.
   BuddyDNS Delegation LAB - check, trace and visualize delegation of your domain.
   dnssec-debugger - DS or DNSKEY records validator.
   PTRarchive.com - this site is responsible for the safekeeping of historical reverse DNS records.
   xip.io - wildcard DNS for everyone.
   nip.io - dead simple wildcard DNS for any IP Address.
   dnslookup (ceipam) - one of the best DNS propagation checker (and not only).
   What's My DNS - DNS propagation checking tool.
   DNSGrep - quickly searching large DNS datasets.

   smtp-tls-checker - check an email domain for SMTP TLS support.
   MX Toolbox - all of your MX record, DNS, blacklist and SMTP diagnostics in one integrated tool.
   Secure Email - complete email test tools for email technicians.
   blacklistalert - checks to see if your domain is on a Real Time Spam Blacklist.
   MultiRBL - complete IP check for sending Mailservers.
   DKIM SPF & Spam Assassin Validator - checks mail authentication and scores messages with Spam Assassin.

   URL Encode/Decode - tool from above to either encode or decode a string of text.
   Uncoder - the online translator for search queries on log data.
   Regex101 - online regex tester and debugger: PHP, PCRE, Python, Golang and JavaScript.
   RegExr - online tool to learn, build, & test Regular Expressions (RegEx / RegExp).
   RegEx Testing - online regex testing tool.
   RegEx Pal - online regex testing tool + other tools.
   The Cyber Swiss Army Knife - a web app for encryption, encoding, compression and data analysis.

   Netcraft - detailed report about the site, helping you to make informed choices about their integrity.*
   RIPE NCC Atlas - a global, open, distributed Internet measurement platform.
   Robtex - uses various sources to gather public information about IP numbers, domain names, host names, etc.
   Security Trails - APIs for Security Companies, Researchers and Teams.
   Online Curl - curl test, analyze HTTP Response Headers.
   Online Tools for Developers - HTTP API tools, testers, encoders, converters, formatters, and other tools.
   Ping.eu - online Ping, Traceroute, DNS lookup, WHOIS and others.
   Network-Tools - network tools for webmasters, IT technicians & geeks.
   BGPview - search for any ASN, IP, Prefix or Resource name.
   Is BGP safe yet? - check BGP (RPKI) security of ISPs and other major Internet players.
   Riseup - provides online communication tools for people and groups working on liberatory social change.
   VirusTotal - analyze suspicious files and URLs to detect types of malware.

   privacyguides.org - provides knowledge and tools to protect your privacy against global mass surveillance.
   DNS Privacy Test Servers - DNS privacy recursive servers list (with a 'no logging' policy).

   ShellCheck - finds bugs in your shell scripts.
   explainshell - get interactive help texts for shell commands.
   jsbin - live pastebin for HTML, CSS & JavaScript, and more.
   CodeSandbox - online code editor for web application development.
   PHP Sandbox - test your PHP code with this code tester.
   Repl.it - an instant IDE to learn, build, collaborate, and host all in one place.
   vclFiddle - is an online tool for experimenting with the Varnish Cache VCL.
   Haskell Dockerfile Linter - a smarter Dockerfile linter that helps you build best practice Docker images.

   GTmetrix - analyze your site’s speed and make it faster.
   Sucuri loadtimetester - test here the performance of any of your sites from across the globe.
   Pingdom Tools - analyze your site’s speed around the world.
   PingMe.io - run website latency tests across multiple geographic regions.
   PageSpeed Insights - analyze your site’s speed and make it faster.
   web.dev - helps developers like you learn and apply the web's modern capabilities to your own sites and apps.
   Lighthouse - automated auditing, performance metrics, and best practices for the web.

   Censys - platform that helps information security practitioners discover, monitor, and analyze devices.
   Shodan - the world's first search engine for Internet-connected devices.
   Shodan 2000 - this tool looks for randomly generated data from Shodan.
   GreyNoise - mass scanner such as Shodan and Censys.
   ZoomEye - search engine for cyberspace that lets the user find specific network components.
   netograph - tools to monitor and understand deep structure of the web.
   FOFA - is a cyberspace search engine.
   onyphe - is a search engine for open-source and cyber threat intelligence data collected.
   IntelligenceX - is a search engine and data archive.
   binaryedge - it scan the entire internet space and create real-time threat intelligence streams and reports.
   Spyse - Internet assets registry: networks, threats, web objects, etc.
   wigle - is a submission-based catalog of wireless networks. All the networks. Found by Everyone.
   PublicWWW - find any alphanumeric snippet, signature or keyword in the web pages HTML, JS and CSS code.
   IntelTechniques - this repository contains hundreds of online search utilities.
   hunter - lets you find email addresses in seconds and connect with the people that matter for your business.
   GhostProject? - search by full email address or username.
   databreaches - was my email affected by data breach?
   We Leak Info - world's fastest and largest data breach search engine.
   Pulsedive - scans of malicious URLs, IPs, and domains, including port scans and web requests.
   Buckets by Grayhatwarfar - database with public search for Open Amazon S3 Buckets and their contents.
   Vigilante.pw - the breached database directory.
   builtwith - find out what websites are built with.
   NerdyData - search the web's source code for technologies, across millions of sites.
   zorexeye - search for sites, images, apps, softwares & more.
   Mamont's open FTP Index - if a target has an open FTP site with accessible content it will be listed here.
   OSINT Framework - focused on gathering information from free tools or resources.
   maltiverse - is a service oriented to cybersecurity analysts.
   Leaked Source - is a collaboration of data found online in the form of a lookup.
   We Leak Info - to help everyday individuals secure their online life, avoiding getting hacked.
   pipl - is the place to find the person behind the email address, social username or phone number.
   abuse.ch - is operated by a random swiss guy fighting malware for non-profit.
   malc0de - malware search engine.
   Cybercrime Tracker - monitors and tracks various malware families that are used to perpetrate cyber crimes.
   shhgit - find GitHub secrets in real time.
   searchcode - helping you find real world examples of functions, API's and libraries.
   Insecam - the world biggest directory of online surveillance security cameras.
   index-of - contains great stuff like: security, hacking, reverse engineering, cryptography, programming etc.
   Rapid7 Labs Open Data - is a great resources of datasets from Project Sonar.
   Common Response Headers - the largest database of HTTP response headers.
   InQuest Labs - InQuest Labs is an open, interactive, and API driven data portal for security researchers.

   thispersondoesnotexist - generate fake faces in one click - endless possibilities.
   AI Generated Photos - 100.000 AI generated faces.
   fakenamegenerator - your randomly generated identity.
   Intigriti Redirector - open redirect/SSRF payload generator.

   have i been pwned? - check if you have an account that has been compromised in a data breach.
   dehashed - is a hacked database search engine.
   Leaked Source - is a collaboration of data found online in the form of a lookup.

   CVE Mitre - list of publicly known cybersecurity vulnerabilities.
   CVE Details - CVE security vulnerability advanced database.
   Exploit DB - CVE compliant archive of public exploits and corresponding vulnerable software.
   0day.today - exploits market provides you the possibility to buy/sell zero-day exploits.
   sploitus - the exploit and tools database.
   cxsecurity - free vulnerability database.
   Vulncode-DB - is a database for vulnerabilities and their corresponding source code if available.
   cveapi - free API for CVE data.

   ImmuniWeb® Mobile App Scanner - test security and privacy of mobile apps (iOS & Android).
   Quixxi - free Mobile App Vulnerability Scanner for Android & iOS.
   Ostorlab - analyzes mobile application to identify vulnerabilities and potential weaknesses.

   Startpage - the world's most private search engine.
   searX - a privacy-respecting, hackable metasearch engine.
   darksearch - the 1st real Dark Web search engine.
   Qwant - the search engine that respects your privacy.
   DuckDuckGo - the search engine that doesn't track you.
   Swisscows - privacy safe web search
   Disconnect - the search engine that anonymizes your searches.
   MetaGer - the search engine that uses anonymous proxy and hidden Tor branches.

   CounterMail - online email service, designed to provide maximum security and privacy.
   Mail2Tor - is a Tor Hidden Service that allows anyone to send and receive emails anonymously.
   Tutanota - is the world's most secure email service and amazingly easy to use.
   Protonmail - is the world's largest secure email service, developed by CERN and MIT scientists.
   Startmail - private & encrypted email made easy.

   Keybase - it's open source and powered by public-key cryptography.

   SKS OpenPGP Key server - services for the SKS keyservers used by OpenPGP.

   Slackware - the most "Unix-like" Linux distribution.
   OpenBSD - multi-platform 4.4BSD-based UNIX-like operating system.
   HardenedBSD - HardenedBSD aims to implement innovative exploit mitigation and security solutions.
   Kali Linux - Linux distribution used for Penetration Testing, Ethical Hacking and network security assessments.
   Parrot Security OS - cyber security GNU/Linux environment.
   Backbox Linux - penetration test and security assessment oriented Ubuntu-based Linux distribution.
   BlackArch - is an Arch Linux-based penetration testing distribution for penetration testers.
   Pentoo - is a security-focused livecd based on Gentoo.
   Security Onion - Linux distro for intrusion detection, enterprise security monitoring, and log management.
   Tails - is a live system that aims to preserve your privacy and anonymity.
   vedetta - OpenBSD router boilerplate.
   Qubes OS - is a security-oriented OS that uses Xen-based virtualization.

   Varnish Cache - HTTP accelerator designed for content-heavy dynamic web sites.
   Nginx - open source web and reverse proxy server that is similar to Apache, but very light weight.
   OpenResty - is a dynamic web platform based on NGINX and LuaJIT.
   Tengine - a distribution of Nginx with some advanced features.
   Caddy Server - is an open source, HTTP/2-enabled web server with HTTPS by default.
   HAProxy - the reliable, high performance TCP/HTTP load balancer.

   Unbound - validating, recursive, and caching DNS resolver (with TLS).
   Knot Resolver - caching full resolver implementation, including both a resolver library and a daemon.
   PowerDNS - is an open source authoritative DNS server, written in C++ and licensed under the GPL.

   3proxy - tiny free proxy server.

   Emerald Onion - is a 501(c)(3) nonprofit organization and transit internet service provider (ISP).
   pi-hole - the Pi-hole® is a DNS sinkhole that protects your devices from unwanted content.
   maltrail - malicious traffic detection system.
   security_monkey - monitors AWS, GCP, OpenStack, and GitHub orgs for assets and their changes over time.
   firecracker - secure and fast microVMs for serverless computing.
   streisand - sets up a new server running your choice of WireGuard, OpenSSH, OpenVPN, and more.

   CapAnalysis - web visual tool to analyze large amounts of captured network traffic (PCAP analyzer).
   netbox - IP address management (IPAM) and data center infrastructure management (DCIM) tool.

   NRE Labs - learn automation by doing it. Right now, right here, in your browser.

   LBNL's Network Research Group - home page of the Network Research Group (NRG).

   gvisor - container runtime sandbox.
   ctop - top-like interface for container metrics.

   Moby - a collaborative project for the container ecosystem to assemble container-based system.
   Traefik - open source reverse proxy/load balancer provides easier integration with Docker and Let's encrypt.
   kong - The Cloud-Native API Gateway.
   rancher - complete container management platform.
   portainer - making Docker management easy.
   nginx-proxy - automated nginx proxy for Docker containers using docker-gen.
   bunkerized-nginx - nginx docker image "secure by default".

   docker-bench-security - checks for dozens of common best-practices around deploying Docker.
   trivy - vulnerability scanner for containers, suitable for CI.
   Harbor - cloud native registry project that stores, signs, and scans content.
   Houdini - hundreds of offensive and useful docker images for network intrusion.

   docker-cheat-sheet - a quick reference cheat sheet on Docker.
   awesome-docker - a curated list of Docker resources and projects.
   docker_practice - learn and understand Docker technologies, with real DevOps practice!
   labs - is a collection of tutorials for learning how to use Docker with various tools.
   dockerfiles - various Dockerfiles I use on the desktop and on servers.
   kubernetes-the-hard-way - bootstrap Kubernetes the hard way on Google Cloud Platform. No scripts.
   kubernetes-the-easy-way - bootstrap Kubernetes the easy way on Google Cloud Platform. No scripts.
   cheatsheet-kubernetes-A4 - Kubernetes CheatSheets in A4.
   k8s-security - kubernetes security notes and best practices.
   kubernetes-production-best-practices - checklists with best-practices for production-ready Kubernetes.
   kubernetes-production-best-practices - kubernetes security - best practice guide.
   kubernetes-failure-stories - is a compilation of public failure/horror stories related to Kubernetes.

   pure-bash-bible - is a collection of pure bash alternatives to external processes.
   pure-sh-bible - is a collection of pure POSIX sh alternatives to external processes.
   bash-guide - is a guide to learn bash.
   bash-handbook - for those who wanna learn Bash.
   The Bash Hackers Wiki - hold documentation of any kind about GNU Bash.
   Shell & Utilities - describes the commands offered to application programs by POSIX-conformant systems.
   the-art-of-command-line - master the command line, in one page.
   Shell Style Guide - a shell style guide for Google-originated open-source projects.

   Vim Cheat Sheet - great multi language vim guide.

   Awesome Python - a curated list of awesome Python frameworks, libraries, software and resources.
   python-cheatsheet - comprehensive Python cheatsheet.
   pythoncheatsheet.org - basic reference for beginner and advanced developers.

   F’Awk Yeah! - advanced sed and awk usage (Parsing for Pentesters 3).

   nixCraft - linux and unix tutorials for new and seasoned sysadmin.
   TecMint - the ideal Linux blog for Sysadmins & Geeks.
   Omnisecu - free Networking, System Administration and Security tutorials.
   linux-cheat - Linux tutorials and cheatsheets. Minimal examples. Mostly user-land CLI utilities.
   linuxupskillchallenge - learn the skills required to sysadmin.
   Unix Toolbox - Unix/Linux/BSD commands and tasks which are useful for IT work or for advanced users.
   Linux Kernel Teaching - is a collection of lectures and labs Linux kernel topics.
   htop explained - explanation of everything you can see in htop/top on Linux.
   Linux Guide and Hints - tutorials on system administration in Fedora and CentOS.
   strace-little-book - a little book which introduces strace.
   linux-tracing-workshop - examples and hands-on labs for Linux tracing tools workshops.
   http2-explained - a detailed document explaining and documenting HTTP/2.
   http3-explained - a document describing the HTTP/3 and QUIC protocols.
   HTTP/2 in Action - an excellent introduction to the new HTTP/2 standard.
   Let's code a TCP/IP stack - great stuff to learn network and system programming at a deeper level.
   Nginx Admin's Handbook - how to improve NGINX performance, security and other important things.
   nginxconfig.io - NGINX config generator on steroids.
   openssh guideline - is to help operational teams with the configuration of OpenSSH server and client.
   SSH Handshake Explained - is a relatively brief description of the SSH handshake.
   ISC's Knowledgebase - you'll find some general information about BIND 9, ISC DHCP, and Kea DHCP.
   PacketLife.net - a place to record notes while studying for Cisco's CCNP certification.

   AD-Attack-Defense - attack and defend active directory using modern post exploitation activity.

   The System Design Primer - learn how to design large-scale systems.
   Awesome Scalability - best practices in building High Scalability, High Availability, High Stability, and more.
   Web Architecture 101 - the basic architecture concepts.

   CIS Benchmarks - secure configuration settings for over 100 technologies, available as a free PDF.
   Security Harden CentOS 7 - this walks you through the steps required to security harden CentOS.
   CentOS 7 Server Hardening Guide - great guide for hardening CentOS; familiar with OpenSCAP.
   awesome-security-hardening - is a collection of security hardening guides, tools and other resources.
   The Practical Linux Hardening Guide - provides a high-level overview of hardening GNU/Linux systems.
   Linux Hardening Guide - how to harden Linux as much as possible for security and privacy.

   Hacking Articles - LRaj Chandel's Security & Hacking Blog.
   AWS security tools - make your AWS cloud environment more secure.
   Rawsec's CyberSecurity Inventory - an inventory of tools and resources about CyberSecurity.
   The Illustrated TLS Connection - every byte of a TLS connection explained and reproduced.
   SSL Research - SSL and TLS Deployment Best Practices by SSL Labs.
   SELinux Game - learn SELinux by doing. Solve Puzzles, show skillz.
   Certificates and PKI - everything you should know about certificates and PKI but are too afraid to ask.
   The Art of Subdomain Enumeration - a reference for subdomain enumeration techniques.
   Quitting Google - the comprehensive guide to quitting Google.

   OWASP - worldwide not-for-profit charitable organization focused on improving the security of software.
   OWASP ASVS 3.0.1 - OWASP Application Security Verification Standard Project.
   OWASP ASVS 3.0.1 Web App - simple web app that helps developers understand the ASVS requirements.
   OWASP ASVS 4.0 - is a list of application security requirements or tests.
   OWASP Testing Guide v4 - includes a "best practice" penetration testing framework.
   OWASP Dev Guide - this is the development version of the OWASP Developer Guide.
   OWASP WSTG - is a comprehensive open source guide to testing the security of web apps.
   OWASP API Security Project - focuses specifically on the top ten vulnerabilities in API security.
   Mozilla Web Security - help operational teams with creating secure web applications.
   security-bulletins - security bulletins that relate to Netflix Open Source.
   API-Security-Checklist - security countermeasures when designing, testing, and releasing your API.
   Enable CORS - enable cross-origin resource sharing.
   Application Security Wiki - is an initiative to provide all application security related resources at one place.
   Weird Proxies - reverse proxy related attacks; it is a result of analysis of various proxies.
   Webshells - great series about malicious payloads.
   Practical Web Cache Poisoning - show you how to compromise websites by using esoteric web features.
   Hidden directories and files - as a source of sensitive information about web application.
   Explosive blog - great blog about cybersec and pentests.
   Security Cookies - this paper will take a close look at cookie security.
   APISecurityBestPractices - help you keep secrets (API keys, db credentials, certificates) out of source code.

   LZone Cheat Sheets - all cheat sheets.
   Dan’s Cheat Sheets’s - massive cheat sheets documentation.
   Rico's cheatsheets - this is a modest collection of cheatsheets.
   DevDocs API - combines multiple API documentations in a fast, organized, and searchable interface.
   cheat.sh - the only cheat sheet you need.
   gnulinux.guru - collection of cheat sheets about bash, vim and networking.
   Web Skills - visual overview of useful skills to learn as a web developer.

   free-programming-books - list of free learning resources in many languages.

   CTF Series : Vulnerable Machines - the steps below could be followed to find vulnerabilities and exploits.
   50M_CTF_Writeup - $50 million CTF from Hackerone - writeup.
   ctf-tasks - an archive of low-level CTF challenges developed over the years.
   How to start RE/malware analysis? - collection of some hints and useful links for the beginners.
   The C10K problem - it's time for web servers to handle ten thousand clients simultaneously, don't you think?
   How 1500 bytes became the MTU of the internet - great story about the Maximum Transmission Unit.
   poor man's profiler - like dtrace's don't really provide methods to see what programs are blocking on.
   HTTPS on Stack Overflow - this is the story of a long journey regarding the implementation of SSL.
   Julia's Drawings - some drawings about programming and unix world, zines about systems & debugging tools.
   Hash collisions - this great repository is focused on hash collisions exploitation.
   sha256-animation - animation of the SHA-256 hash function in your terminal.
   sha256algorithm - sha256 algorithm explained online step by step visually.
   BGP Meets Cat - after 3072 hours of manipulating BGP, Job Snijders has succeeded in drawing a Nyancat.
   bgp-battleships - playing battleships over BGP.
   What happens when... - you type google.com into your browser and press enter?
   how-web-works - based on the 'What happens when...' repository.
   HTTPS in the real world - great tutorial explain how HTTPS works in the real world.
   Gitlab and NFS bug - how we spent two weeks hunting an NFS bug in the Linux kernel.
   Gitlab melts down - postmortem on the database outage of January 31 2017 with the lessons we learned.
   How To Become A Hacker - if you want to be a hacker, keep reading.
   Operation Costs in CPU - should help to estimate costs of certain operations in CPU clocks.
   Let's Build a Simple Database - writing a sqlite clone from scratch in C.
   simple-computer - great resource to understand how computers work under the hood.
   The story of "Have I been pwned?" - working with 154 million records on Azure Table Storage.
   TOP500 Supercomputers - shows the 500 most powerful commercially available computer systems.
   How to build a 8 GPU password cracker - hours of frustration like desktop components do.
   CERN Data Centre - 3D visualizations of the CERN computing environments (and more).
   How fucked is my database - evaluate how fucked your database is with this handy website.
   Linux Troubleshooting 101 , 2016 Edition - everything is a DNS Problem...
   Five Whys - you know what the problem is, but you cannot solve it?
   Maersk, me & notPetya - how did ransomware successfully hijack hundreds of domain controllers?
   howhttps.works - how HTTPS works ...in a comic!
   howdns.works - a fun and colorful explanation of how DNS works.
   POSTGRESQLCO.NF - your postgresql.conf documentation and recommendations.

   Awesome Sysadmin - amazingly awesome open source sysadmin resources.
   Awesome Shell - awesome command-line frameworks, toolkits, guides and gizmos.
   Command-line-text-processing - finding text to search and replace, sorting to beautifying, and more.
   Awesome Pcaptools - collection of tools developed by other researchers to process network traces.
   awesome-ebpf - a curated list of awesome projects related to eBPF.
   Linux Network Performance - where some of the network sysctl variables fit into the Linux/Kernel network flow.
   Awesome Postgres - list of awesome PostgreSQL software, libraries, tools and resources.
   quick-SQL-cheatsheet - a quick reminder of all SQL queries and examples on how to use them.
   Awesome-Selfhosted - list of Free Software network services and web applications which can be hosted locally.
   List of applications - huge list of apps sorted by category, as a reference for those looking for packages.
   CS-Interview-Knowledge-Map - build the best interview map.
   DevOps-Guide - DevOps Guide from basic to advanced with Interview Questions and Notes.
   FreeBSD Journal - it is a great list of periodical magazines about FreeBSD and other important things.
   devops-interview-questions - contains interview questions on various DevOps and SRE related topics.

   Web Developer Roadmap - roadmaps, articles and resources to help you choose your path, learn and improve.
   Front-End-Checklist - the perfect Front-End Checklist for modern websites and meticulous developers.
   Front-End-Performance-Checklist - Front-End Performance Checklist that runs faster than the others.
   Python's Magic Methods - what are magic methods? They're everything in object-oriented Python.
   wtfpython - a collection of surprising Python snippets and lesser-known features.
   js-dev-reads - a list of books and articles for the discerning web developer to read.
   Commit messages guide - a guide to understand the importance of commit messages.

   Awesome Web Security - a curated list of Web Security materials and resources.
   awesome-cyber-skills - a curated list of hacking environments where you can train your cyber skills.
   awesome-devsecops - an authoritative list of awesome devsecops tools.
   awesome-osint - is a curated list of amazingly awesome OSINT.
   HolyTips - tips and tutorials on Bug Bounty Hunting and Web App Security.
   awesome-threat-intelligence - a curated list of Awesome Threat Intelligence resources.
   Red-Teaming-Toolkit - a collection of open source and commercial tools that aid in red team operations.
   awesome-burp-extensions - a curated list of amazingly awesome Burp Extensions.
   Free Security eBooks - list of a Free Security and Hacking eBooks.
   Hacking-Security-Ebooks - top 100 Hacking & Security E-Books.
   privacy-respecting - curated list of privacy respecting services and software.
   reverse-engineering - list of awesome reverse engineering resources.
   linux-re-101 - a collection of resources for linux reverse engineering.
   reverseengineering-reading-list - a list of Reverse Engineering articles, books, and papers.
   Awesome-WAF - a curated list of awesome web-app firewall (WAF) stuff.
   awesome-shodan-queries - interesting, funny, and depressing search queries to plug into shodan.io.
   RobotsDisallowed - a curated list of the most common and most interesting robots.txt disallowed directories.
   HackingNeuralNetworks - is a small course on exploiting and defending neural networks.
   wildcard-certificates - why you probably shouldn't use a wildcard certificate.
   Don't use VPN services - which is what every third-party "VPN provider" does.
   awesome-yara - a curated list of awesome YARA rules, tools, and people.
   macOS-Security-and-Privacy-Guide - guide to securing and improving privacy on macOS.
   macos_security - macOS Security Compliance Project.
   awesome-sec-talks - is a collected list of awesome security talks.
   Movies for Hackers - list of movies every hacker & cyberpunk must watch.
   Cryptography_1 - materials used whilst taking Prof. Dan Boneh Stanford Crypto course.
   Crypton - library to learn and practice Offensive and Defensive Cryptography.

   Cheatography - over 3,000 free cheat sheets, revision aids and quick references.
   awesome-static-analysis - static analysis tools for all programming languages.
   computer-science - path to a free self-taught education in Computer Science.
   post-mortems - is a collection of postmortems (config errors, hardware failures, and more).
   build-your-own-x - build your own (insert technology here).
   Project-Based-Tutorials-in-C - is a curated list of project-based tutorials in C.
   The-Documentation-Compendium - various README templates & tips on writing high-quality documentation.
   awesome-python-applications - free software that works great, and also happens to be open-source Python.
   awesome-public-datasets - a topic-centric list of HQ open datasets.
   machine-learning-algorithms - a curated list of all machine learning algorithms and concepts.

   Varnish for PHP developers - very interesting presentation of Varnish by Mattias Geniar.
   A Netflix Guide to Microservices - talks about the chaotic and vibrant world of microservices at Netflix.

   Comparing C to machine lang - compare a simple C app with the compiled machine code of that program.

   Brendan Gregg's Blog - is an industry expert in computing performance and cloud computing.
   Gynvael "GynDream" Coldwind - is a IT security engineer at Google.
   Michał "lcamtuf" Zalewski - white hat hacker, computer security expert.
   Mattias Geniar - developer, sysadmin, blogger, podcaster and public speaker.
   Nick Craver - software developer and systems administrator for Stack Exchange.
   Scott Helme - security researcher, speaker and founder of securityheaders.com and report-uri.com.
   Brian Krebs - The Washington Post and now an Independent investigative journalist.
   Bruce Schneier - is an internationally renowned security technologist, called a "security guru".
   Chrissy Morgan - advocate of practical learning, Chrissy also takes part in bug bounty programs.
   Andy Gill - is a hacker at heart who works as a senior penetration tester.
   Daniel Miessler - cybersecurity expert and writer.
   Samy Kamkar - is an American privacy and security researcher, computer hacker.
   Javvad Malik - is a security advocate at AlienVault, a blogger event speaker and industry commentator.
   Graham Cluley - public speaker and independent computer security analyst.
   Kacper Szurek - detection engineer at ESET.
   Troy Hunt - web security expert known for public education and outreach on security topics.
   raymii.org - sysadmin specializing in building high availability cloud environments.
   Robert Penz - IT security expert.

   Linux Audit - the Linux security blog about auditing, hardening and compliance by Michael Boelen.
   Linux Security Expert - trainings, howtos, checklists, security tools, and more.
   The Grymoire - collection of useful incantations for wizards, be you computer wizards, magicians, or whatever.
   Secjuice - is the only non-profit, independent and volunteer led publication in the information security space.
   Decipher - security news that informs and inspires.

   Tenable Podcast - conversations and interviews related to Cyber Exposure, and more.
   Sophos - threat news room, giving you news, opinion, advice and research on computer security issues.
   Tripwire State of Security - blog featuring the latest news, trends and insights on current security issues.
   Malwarebytes Labs Blog - security blog aims to provide insider news about cybersecurity.
   TrustedSec - latest news, and trends about cybersecurity.
   PortSwigger Web Security Blog - about web app security vulns and top tips from our team of web security.
   AT&T Cybersecurity blog - news on emerging threats and practical advice to simplify threat detection.
   Thycotic - where CISOs and IT Admins come to learn about industry trends, IT security, and more.

   Risky Business - is a weekly information security podcast featuring news and in-depth interviews.
   Cyber, by Motherboard - stories, and focus on the ideas about cybersecurity.
   Tenable Podcast - conversations and interviews related to Cyber Exposure, and more.
   Cybercrime Investigations - podcast by Geoff White about cybercrimes.
   The many hats club - featuring stories from a wide range of Infosec people (Whitehat, Greyhat and Blackhat).
   Darknet Diaries - true stories from the dark side of the Internet.
   OSINTCurious Webcasts - is the investigative curiosity that helps people be successful in OSINT.
   Security Weekly - the latest information security and hacking news.

   rev3rse security - offensive, binary exploitation, web app security, hardening, red team, blue team.
   LiveOverflow - a lot more advanced topics than what is typically offered in paid online courses - but for free.
   J4vv4D - the important information regarding our internet security.
   CyberTalks - talks, interviews, and article about cybersecurity.

   @blackroomsec - a white-hat hacker/pentester. Intergalactic Minesweeper Champion 1990.
   @MarcoCiappelli - Co-Founder @ITSPmagazine, at the intersection of IT security and society.
   @binitamshah - Linux Evangelist. Malwares. Kernel Dev. Security Enthusiast.
   @joe_carson - an InfoSec Professional and Tech Geek.
   @mikko - CRO at F-Secure, Reverse Engineer, TED Speaker, Supervillain.
   @esrtweet - often referred to as ESR, is an American software developer, and open-source software advocate.
   @gynvael - security researcher/programmer, @DragonSectorCTF founder/player, technical streamer.
   @x0rz - Security Researcher & Cyber Observer.
   @hasherezade - programmer, malware analyst. Author of PEbear, PEsieve, libPeConv.
   @TinkerSec - tinkerer, cypherpunk, hacker.
   @alisaesage - independent hacker and researcher.
   @SwiftOnSecurity - systems security, industrial safety, sysadmin, author of decentsecurity.com.
   @dakami - is one of just seven people with the authority to restore the DNS root keys.
   @samykamkar - is a famous "grey hat" hacker, security researcher, creator of the MySpace "Samy" worm.
   @securityweekly - founder & CTO of Security Weekly podcast network.
   @jack_daniel - @SecurityBSides co-founder.
   @thegrugq - Security Researcher.
   @matthew_d_green - a cryptographer and professor at Johns Hopkins University.

   @haveibeenpwned - check if you have an account that has been compromised in a data breach.
   @bugcrowd - trusted by more of the Fortune 500 than any other crowdsourced security platform.
   @Malwarebytes - most trusted security company. Unmatched threat visibility.
   @sansforensics - the world's leading Digital Forensics and Incident Response provider.
   @attcyber - AT&T Cybersecurity’s Edge-to-Edge technologies provide threat intelligence, and more.
   @TheManyHatsClub - an information security focused podcast and group of individuals from all walks of life.
   @hedgehogsec - Hedgehog Cyber. Gibraltar and Manchester's top boutique information security firm.
   @NCSC - the National Cyber Security Centre. Helping to make the UK the safest place to live and work online.
   @Synacktiv - IT security experts.

   How to Do Things at ARL - how to configure modems, scan images, record CD-ROMs, and other.*

   Diffie-Hellman Key Exchange (short version) - how Diffie-Hellman Key Exchange worked.

   Sandcat Browser - a penetration-oriented browser with plenty of advanced functionality already built in.
   Metasploit - tool and framework for pentesting system, web and many more.
   Burp Suite - tool for testing web app security, intercepting proxy to replay, inject, scan and fuzz.
   OWASP Zed Attack Proxy - intercepting proxy to replay, inject, scan and fuzz HTTP requests.
   w3af - is a Web Application Attack and Audit Framework.
   mitmproxy - an interactive TLS-capable intercepting HTTP proxy for penetration testers.
   Nikto2 - web server scanner which performs comprehensive tests against web servers for multiple items.
   sqlmap - tool that automates the process of detecting and exploiting SQL injection flaws.
   Recon-ng - is a full-featured Web Reconnaissance framework written in Python.
   AutoRecon - is a network reconnaissance tool which performs automated enumeration of services.
   Faraday - an Integrated Multiuser Pentest Environment.
   Photon - incredibly fast crawler designed for OSINT.
   XSStrike - most advanced XSS detection suite.
   Sn1per - automated pentest framework for offensive security experts.
   vuls - is an agent-less vulnerability scanner for Linux, FreeBSD, and other.
   tsunami - is a general purpose network security scanner with an extensible plugin system.
   aquatone - a tool for domain flyovers.
   BillCipher - information gathering tool for a website or IP address.
   WhatWaf - detect and bypass web application firewalls and protection systems.
   Corsy - CORS misconfiguration scanner.
   Raccoon - is a high performance offensive security tool for reconnaissance and vulnerability scanning.
   dirhunt - find web directories without bruteforce.
   John The Ripper - is a fast password cracker, currently available for many flavors of Unix, Windows, and other.
   hashcat - world's fastest and most advanced password recovery utility.
   p0f - is a tool to identify the players behind any incidental TCP/IP communications.
   ssh_scan - a prototype SSH configuration and policy scanner.
   LeakLooker - find open databases - powered by Binaryedge.io
   exploitdb - searchable archive from The Exploit Database.
   getsploit - is a command line utility for searching and downloading exploits.
   ctf-tools - some setup scripts for security research tools.
   pwntools - CTF framework and exploit development library.
   security-tools - collection of small security tools created mostly in Python. CTFs, pentests and so on.
   pentestpackage - is a package of Pentest scripts.
   python-pentest-tools - python tools for penetration testers.
   fuzzdb - dictionary of attack patterns and primitives for black-box application fault injection.
   AFL - is a free software fuzzer maintained by Google.
   AFL++ - is AFL with community patches.
   syzkaller - is an unsupervised, coverage-guided kernel fuzzer.
   pwndbg - exploit development and reverse engineering with GDB made easy.
   GDB PEDA - Python Exploit Development Assistance for GDB.
   IDA - multi-processor disassembler and debugger useful for reverse engineering malware.
   radare2 - framework for reverse-engineering and analyzing binaries.
   routersploit - exploitation framework for embedded devices.
   Ghidra - is a software reverse engineering (SRE) framework.
   Cutter - is an SRE platform integrating Ghidra's decompiler.
   Vulnreport - open-source pentesting management and automation platform by Salesforce Product Security.
   Mentalist - is a graphical tool for custom wordlist generation.
   archerysec - vulnerability assessment and management helps to perform scans and manage vulnerabilities.
   Osmedeus - fully automated offensive security tool for reconnaissance and vulnerability scanning.
   beef - the browser exploitation framework project.
   AutoSploit - automated mass exploiter.
   SUDO_KILLER - is a tool to identify and exploit sudo rules' misconfigurations and vulnerabilities.
   yara - the pattern matching swiss knife.
   mimikatz - a little tool to play with Windows security.
   sherlock - hunt down social media accounts by username across social networks.
   OWASP Threat Dragon - is a tool used to create threat model diagrams and to record possible threats.

   PTES - the penetration testing execution standard.
   Pentests MindMap - amazing mind map with vulnerable apps and systems.
   WebApps Security Tests MindMap - incredible mind map for WebApps security tests.
   Brute XSS - master the art of Cross Site Scripting.
   XSS cheat sheet - contains many vectors that can help you bypass WAFs and filters.
   Offensive Security Bookmarks - security bookmarks collection, all things that author need to pass OSCP.
   Awesome Pentest Cheat Sheets - collection of the cheat sheets useful for pentesting.
   Awesome Hacking by HackWithGithub - awesome lists for hackers, pentesters and security researchers.
   Awesome Hacking by carpedm20 - a curated list of awesome hacking tutorials, tools and resources.
   Awesome Hacking Resources - collection of hacking/penetration testing resources to make you better.
   Awesome Pentest - collection of awesome penetration testing resources, tools and other shiny things.
   Awesome-Hacking-Tools - is a curated list of awesome Hacking Tools.
   Hacking Cheat Sheet - author hacking and pentesting notes.
   blackhat-arsenal-tools - official Black Hat arsenal security tools repository.
   Penetration Testing and WebApp Cheat Sheets - the complete list of Infosec related cheat sheets.
   Cyber Security Resources - includes thousands of cybersecurity-related references and resources.
   Pentest Bookmarks - there are a LOT of pentesting blogs.
   Cheatsheet-God - Penetration Testing Reference Bank - OSCP/PTP & PTX Cheatsheet.
   ThreatHunter-Playbook - to aid the development of techniques and hypothesis for hunting campaigns.
   Beginner-Network-Pentesting - notes for beginner network pentesting course.
   OSCPRepo - is a list of resources that author have been gathering in preparation for the OSCP.
   PayloadsAllTheThings - a list of useful payloads and bypass for Web Application Security and Pentest/CTF.
   payloads - git all the Payloads! A collection of web attack payloads.
   command-injection-payload-list - command injection payload list.
   Awesome Shodan Search Queries - great search queries to plug into Shodan.
   AwesomeXSS - is a collection of Awesome XSS resources.
   php-webshells - common php webshells.
   Pentesting Tools Cheat Sheet - a quick reference high level overview for typical penetration testing.
   OWASP Cheat Sheet Series - is a collection of high value information on specific application security topics.
   OWASP dependency-check - is an open source solution the OWASP Top 10 2013 entry.
   OWASP ProActive Controls - OWASP Top 10 Proactive Controls 2018.
   PENTESTING-BIBLE - hacking & penetration testing & red team & cyber security resources.
   pentest-wiki - is a free online security knowledge library for pentesters/researchers.
   DEF CON Media Server - great stuff from DEFCON.
   Awesome Malware Analysis - a curated list of awesome malware analysis tools and resources.
   SQL Injection Cheat Sheet - detailed technical stuff about the many different variants of the SQL Injection.
   Entersoft Knowledge Base - great and detailed reference about vulnerabilities.
   HTML5 Security Cheatsheet - a collection of HTML5 related XSS attack vectors.
   XSS String Encoder - for generating XSS code to check your input validation filters against XSS.
   GTFOBins - list of Unix binaries that can be exploited by an attacker to bypass local security restrictions.
   Guifre Ruiz Notes - collection of security, system, network and pentest cheatsheets.
   SSRF Tips - a collection of SSRF Tips.
   shell-storm repo CTF - great archive of CTFs.
   ctf - CTF (Capture The Flag) writeups, code snippets, notes, scripts.
   My-CTF-Web-Challenges - collection of CTF Web challenges.
   MSTG - The Mobile Security Testing Guide (MSTG) is a comprehensive manual for mobile app security testing.
   Internal-Pentest-Playbook - notes on the most common things for an Internal Network Penetration Test.
   KeyHacks - shows quick ways in which API keys leaked by a bug bounty program can be checked.
   securitum/research - various Proof of Concepts of security research performed by Securitum.
   public-pentesting-reports - is a list of public pentest reports released by several consulting security groups.
   awesome-bug-bounty - is a comprehensive curated list of available Bug Bounty.
   bug-bounty-reference - is a list of bug bounty write-ups.
   Awesome-Bugbounty-Writeups - is a curated list of bugbounty writeups.
   Bug bounty writeups - list of bug bounty writeups (2012-2020).
   hackso.me - a great journey into security.

   PHP-backdoors - a collection of PHP backdoors. For educational or testing purposes only.

   Weakpass - for any kind of bruteforce find wordlists or unleash the power of them all at once!
   Hashes.org - is a free online hash resolving service incorporating many unparalleled techniques.
   SecLists - collection of multiple types of lists used during security assessments, collected in one place.
   Probable-Wordlists - sorted by probability originally created for password generation and testing.
   skullsecurity passwords - password dictionaries and leaked passwords repository.
   Polish PREMIUM Dictionary - official dictionary created by the team on the forum bezpieka.org.* ¹
   statistically-likely-usernames - wordlists for creating statistically likely username lists.

   YesWeHack - bug bounty platform with infosec jobs.
   Openbugbounty - allows any security researcher reporting a vulnerability on any website.
   hackerone - global hacker community to surface the most relevant security issues.
   bugcrowd - crowdsourced cybersecurity for the enterprise.
   Crowdshield - crowdsourced security & bug bounty management.
   Synack - crowdsourced security & bug bounty programs, crowd security intelligence platform, and more.
   Hacktrophy - bug bounty platform.

   OWASP-VWAD - comprehensive and well maintained registry of all known vulnerable web applications.
   DVWA - PHP/MySQL web application that is damn vulnerable.
   metasploitable2 - vulnerable web application amongst security researchers.
   metasploitable3 - is a VM that is built from the ground up with a large amount of security vulnerabilities.
   DSVW - is a deliberately vulnerable web application written in under 100 lines of code.
   OWASP Mutillidae II - free, open source, deliberately vulnerable web-application.
   OWASP Juice Shop Project - the most bug-free vulnerable application in existence.
   OWASP Node js Goat Project - OWASP Top 10 security risks apply to web apps developed using Node.js.
   juicy-ctf - run Capture the Flags and Security Trainings with OWASP Juice Shop.
   SecurityShepherd - web and mobile application security training platform.
   Security Ninjas - open source application security training program.
   hackazon - a modern vulnerable web app.
   dvna - damn vulnerable NodeJS application.
   django-DefectDojo - is an open-source application vulnerability correlation and security orchestration tool.
   Google Gruyere - web application exploits and defenses.
   Bodhi - is a playground focused on learning the exploitation of client-side web vulnerabilities.
   Websploit - single vm lab with the purpose of combining several vulnerable appliations in one environment.
   vulhub - pre-built Vulnerable Environments based on docker-compose.
   CloudGoat 2 - the new & improved "Vulnerable by Design" AWS deployment tool.
   secDevLabs - is a laboratory for learning secure web development in a practical manner.
   CORS-vulnerable-Lab - sample vulnerable code and its exploit code.
   RootTheBox - a Game of Hackers (CTF Scoreboard & Game Manager).
   KONTRA - application security training (OWASP Top Web & Api).

   Offensive Security - true performance-based penetration testing training for over a decade.
   Hack The Box - online platform allowing you to test your penetration testing skills.
   Hacking-Lab - online ethical hacking, computer network and security challenge platform.
   pwnable.kr - non-commercial wargame site which provides various pwn challenges.
   Pwnable.tw - is a wargame site for hackers to test and expand their binary exploiting skills.
   picoCTF - is a free computer security game targeted at middle and high school students.
   CTFlearn - is an online platform built to help ethical hackers learn and practice their cybersecurity knowledge.
   ctftime - CTF archive and a place, where you can get some another CTF-related info.
   Silesia Security Lab - high quality security testing services.
   Practical Pentest Labs - pentest lab, take your Hacking skills to the next level.
   Root Me - the fast, easy, and affordable way to train your hacking skills.
   rozwal.to - a great platform to train your pentesting skills.
   TryHackMe - learning Cyber Security made easy.
   hackxor - is a realistic web application hacking game, designed to help players of all abilities develop their skills.
   Hack Yourself First - it's full of nasty app sec holes.
   OverTheWire - can help you to learn and practice security concepts in the form of fun-filled games.
   Wizard Labs - is an online Penetration Testing Lab.
   PentesterLab - provides vulnerable systems that can be used to test and understand vulnerabilities.
   RingZer0 - tons of challenges designed to test and improve your hacking skills.
   try2hack - several security-oriented challenges for your entertainment.
   Ubeeri - preconfigured lab environments.
   Pentestit - emulate IT infrastructures of real companies for legal pen testing and improving pentest skills.
   Microcorruption - reversal challenges done in the web interface.
   Crackmes - download crackmes to help improve your reverse engineering skills.
   DomGoat - DOM XSS security learning and practicing platform.
   Stereotyped Challenges - upgrade your web hacking techniques today!
   Vulnhub - allows anyone to gain practical 'hands-on' experience in digital security.
   W3Challs - is a penetration testing training platform, which offers various computer challenges.
   RingZer0 CTF - offers you tons of challenges designed to test and improve your hacking skills.
   Hack.me - a platform where you can build, host and share vulnerable web apps for educational purposes.
   HackThis! - discover how hacks, dumps and defacements are performed and secure your website.
   Enigma Group WebApp Training - these challenges cover the exploits listed in the OWASP Top 10 Project.
   Reverse Engineering Challenges - challenges, exercises, problems and tasks - by level, by type, and more.
   0x00sec - the home of the Hacker - Malware, Reverse Engineering, and Computer Science.
   We Chall - there are exist a lots of different challenge types.
   Hacker Gateway - is the go-to place for hackers who want to test their skills.
   Hacker101 - is a free class for web security.
   contained.af - a stupid game for learning about containers, capabilities, and syscalls.
   flAWS challenge! - a series of levels you'll learn about common mistakes and gotchas when using AWS.
   CyberSec WTF - provides web hacking challenges derived from bounty write-ups.
   CTF Challenge - CTF Web App challenges.
   gCTF - most of the challenges used in the Google CTF 2017.
   Hack This Site - is a free, safe and legal training ground for hackers.
   Attack & Defense - is a browser-based cloud labs.
   Cryptohack - a fun platform for learning modern cryptography.
   Cryptopals - the cryptopals crypto challenges.
   LabEx - hands-on labs and challenges for cyber security.

   fbctf - platform to host Capture the Flag competitions.
   ctfscoreboard - scoreboard for Capture The Flag competitions.

   Bugcrowd University - open source education content for the researcher community.
   OSCPRepo - a list of resources and scripts that I have been gathering in preparation for the OSCP.
   OWASP Top 10: Real-World Examples - test your web apps with real-world examples (two-part series).
   phrack.org - an awesome collection of articles from several respected hackers and other thinkers.
   Practical-Ethical-Hacking-Resources - compilation of resources from TCM's Udemy Course.

   Feedly - organize, read and share what matters to you.
   Inoreader - similar to feedly with a support for filtering what you fetch from rss.

   #hackerspaces - hackerspace IRC channels.

   The Hacker News - leading news source dedicated to promoting awareness for security experts and hackers.
   Latest Hacking News - provides the latest hacking news, exploits and vulnerabilities for ethical hackers.
   Security Newsletter - security news as a weekly digest (email notifications).
   Google Online Security Blog - the latest news and insights from Google on security and safety on the Internet.
   Qualys Blog - expert network security guidance and news.
   DARKReading - connecting the Information Security Community.
   Darknet - latest hacking tools, hacker news, cybersecurity best practices, ethical hacking & pen-testing.
   publiclyDisclosed - public disclosure watcher who keeps you up to date about the recently disclosed bugs.
   Reddit - Hacking - a subreddit dedicated to hacking and hackers.
   Packet Storm - information security services, news, files, tools, exploits, advisories and whitepapers.
   Sekurak - about security, penetration tests, vulnerabilities and many others (PL/EN).
   nf.sec - basic aspects and mechanisms of Linux operating system security (PL).

   Changelog - is a community of hackers; news & podcasts for developers and hackers.

   Unbound DNS Tutorial - a validating, recursive, and caching DNS server.
   Knot Resolver on Fedora - how to get faster and more secure DNS resolution with Knot Resolver on Fedora.
   DNS-over-HTTPS - tutorial to setup your own DNS-over-HTTPS (DoH) server.
   dns-over-https - a cartoon intro to DNS over HTTPS.
   DNS-over-TLS - following to your DoH server, setup your DNS-over-TLS (DoT) server.
   DNS Servers - how (and why) i run my own DNS Servers.

   OpenSSL Certificate Authority - build your own certificate authority (CA) using the OpenSSL tools.
   step-ca Certificate Authority - build your own certificate authority (CA) using open source step-ca.

   os-tutorial - how to create an OS from scratch.
   Write your Own Virtual Machine - how to write your own virtual machine (VM).
   x86 Bare Metal Examples - dozens of minimal operating systems to learn x86 system programming.
   simple-computer - the scott CPU from "But How Do It Know?" by J. Clark Scott.
   littleosbook - the little book about OS development.

In Firefox's address bar, you can limit results by typing special characters before or after your term:

• ^ - for matches in your browsing history
• * - for matches in your bookmarks.
• % - for matches in your currently open tabs.
• # - for matches in page titles.
• @ - for matches in web addresses.

• chrome://chrome-urls - list of all commands
• chrome://flags - enable experiments and development features
• chrome://interstitials - errors and warnings
• chrome://net-internals - network internals (events, dns, cache)
• chrome://network-errors - network errors
• chrome://net-export - start logging future network activity to a file
• chrome://safe-browsing - safe browsing options
• chrome://user-actions - record all user actions
• chrome://restart - restart chrome
• chrome://dino - ERR_INTERNET_DISCONNECTED...
• cache:<website-address> - view the cached version of the web page

IP addresses can be shortened by dropping the zeroes:

http://1.0.0.1 → http://1.1
http://127.0.0.1 → http://127.1
http://192.168.0.1 → http://192.168.1

http://0xC0A80001 or http://3232235521 → 192.168.0.1
http://192.168.257 → 192.168.1.1
http://192.168.516 → 192.168.2.4

This bypasses WAF filters for SSRF, open-redirect, etc where any IP as input gets blacklisted.

For more information please see How to Obscure Any URL and Magic IP Address Shortcuts.

Hashing

plaintext ➡️ hash
hash ⛔ plaintext

Symmetric encryption

plaintext ➡️ 🔑 ➡️ ciphertext
plaintext ⬅️ 🔑 ⬅️ ciphertext
(:key: shared key)

Asymmetric encryption

plaintext ➡️ 🔑 ➡️ ciphertext
plaintext ⬅️ 〽️ ⬅️ ciphertext
(:key: public key, :part_alternation_mark: private key)

Encoding

text ➡️ encoded
text ⬅️ encoded

• terminal
• busybox
• mount
• fuser
• lsof
• ps
• top
• vmstat
• iostat
• strace
• kill
• find
• diff
• vimdiff
• tail
• cpulimit
• pwdx
• tr
• chmod
• who
• last
• screen
• script
• du
• inotifywait
• openssl
• secure-delete
• dd
• gpg
• system-other
• curl
• httpie
• ssh
• linux-dev
• tcpdump
• tcpick
• ngrep
• hping3
• nmap
• netcat
• socat
• p0f
• gnutls-cli
• netstat
• rsync
• host
• dig
• certbot
• network-other
• git
• awk
• sed
• grep
• perl

exec $SHELL -l

disown -a && exit

kill -9 $$
unset HISTFILE && exit

true && echo success
false || echo failed

some_command > >(/bin/cmd_for_stdout) 2> >(/bin/cmd_for_stderr)

(some_command 2>&1 1>&3 | tee errorlog ) 3>&1 1>&2 | tee stdoutlog

history | \
awk '{CMD[$2]++;count++;}END { for (a in CMD)print CMD[a] " " CMD[a]/count*100 "% " a;}' | \
grep -v "./" | \
column -c3 -s " " -t | \
sort -nr | nl |  head -n 20

function sterile() {

  history | awk '$2 != "history" { $1=""; print $0 }' | egrep -vi "\
curl\b+.*(-E|--cert)\b+.*\b*|\
curl\b+.*--pass\b+.*\b*|\
curl\b+.*(-U|--proxy-user).*:.*\b*|\
curl\b+.*(-u|--user).*:.*\b*
.*(-H|--header).*(token|auth.*)\b+.*|\
wget\b+.*--.*password\b+.*\b*|\
http.?://.+:.+@.*\
" > $HOME/histbuff; history -r $HOME/histbuff;

}

export PROMPT_COMMAND="sterile"

Look also: A naive utility to censor credentials in command history.

cp filename{,.orig}

>filename

rm !(*.foo|*.bar|*.baz)

# cat  >filename ... - overwrite the file
# cat >>filename ... - append to a file
cat > filename << __EOF__
data data data
__EOF__

vim scp://user@host//etc/fstab

mkd() { mkdir -p "$@" && cd "$@"; }

rename 'y/A-Z/a-z/' *

printf "%`tput cols`s" | tr ' ' '#'

history | cut -c 8-
fc -l -n 1 | sed 's/^\s*//'

cat > /etc/profile << __EOF__
_after_logout() {

  username=$(whoami)

  for _pid in $(ps afx | grep sshd | grep "$username" | awk '{print $1}') ; do

    kill -9 $_pid

  done

}
trap _after_logout EXIT
__EOF__

for ((i=1; i<=10; i+=2)) ; do echo $i ; done
# alternative: seq 1 2 10

for ((i=5; i<=10; ++i)) ; do printf '%02d\n' $i ; done
# alternative: seq -w 5 10

for i in {1..10} ; do echo $i ; done

unset MAIL; export MAILCHECK=1; export MAILPATH='$FILE_TO_WATCH?$MESSAGE'

busybox httpd -p $PORT -h $HOME [-c httpd.conf]

mount -t tmpfs tmpfs /mnt -o size=64M

• -t - filesystem type
• -o - mount options

mount -o remount,rw /

fuser /var/log/daemon.log
fuser -v /home/supervisor

fuser -ki filename

• -i - interactive option

fuser -k -HUP filename

• --list-signals - list available signal names

fuser -v 53/udp

fuser -mv /var/www

lsof -P -i -n

lsof -i tcp:443

lsof -Pan -i tcp -i udp

lsof -i -P | grep -i "listen"

lsof -Pnl -i

lsof -Pni4 | grep LISTEN | column -t

lsof -c "process"

lsof -u username -a +D /etc

lsof / | \
awk '{ if($7 > 1048576) print $7/1048576 "MB" " " $9 " " $1 }' | \
sort -n -u | tail | column -t

lsof -p <PID> | grep cwd

ps awwfux | less -S

ps hax -o user | sort | uniq -c | sort -r

ps -lfC nginx

find / -mmin 60 -type f

find / -type f -size +20M

find -type f -exec md5sum '{}' ';' | sort | uniq --all-repeated=separate -w 33

cd /var/www/site && find . -type f -exec chmod 766 {} \;
cd /var/www/site && find . -type f -exec chmod 664 {} +

cd /var/www/site && find . -type d -exec chmod g+x {} \;
cd /var/www/site && find . -type d -exec chmod g+rwx {} +

# User:
find . -user <username> -print
find /etc -type f -user <username> -name "*.conf"

# Group:
find /opt -group <group>
find /etc -type f -group <group> -iname "*.conf"

# User:
find . \! -user <username> -print

# Group:
find . \! -group <group>

# User
find . -user <username> -perm -u+rw # -rw-r--r--
find /home -user $(whoami) -perm 777 # -rwxrwxrwx

# Group:
find /home -type d -group <group> -perm 755 # -rwxr-xr-x

find . -type f -mtime +60 -delete

find . -depth  -type d  -empty -exec rmdir {} \;

find </path/to/dir> -xdev -samefile filename

find . -type f -exec stat --format '%Y :%y %n' "{}" \; | sort -nr | cut -d: -f2- | head

find . -not -path '*/\.git*' -type f -print0 | xargs -0 sed -i 's/foo/bar/g'

find . -depth -name '*test*' -execdir bash -c 'mv -v "$1" "${1//foo/bar}"' _ {} \;

find / \( -perm -4000 -o -perm -2000 \) -type f -exec ls -la {} \;

top -p $(pgrep -d , <str>)

• <str> - process containing string (eg. nginx, worker)

vmstat 2 20 -t -w

• 2 - number of times with a defined time interval (delay)
• 20 - each execution of the command (count)
• -t - show timestamp
• -w - wide output
• -S M - output of the fields in megabytes instead of kilobytes

vmstat 5 -w

vmstat -D

vmstat -s

vmstat -m

iostat 2 10 -t -m

• 2 - number of times with a defined time interval (delay)
• 10 - each execution of the command (count)
• -t - show timestamp
• -m - fields in megabytes (-k - in kilobytes, default)

iostat 2 10 -t -m -c

iostat 2 10 -t -m -d

iostat -N

# 1)
strace -f -p $(pidof glusterfsd)

# 2)
strace -f $(pidof php-fpm | sed 's/\([0-9]*\)/\-p \1/g')

timeout 30 strace $(< /var/run/zabbix/zabbix_agentd.pid)

ps auxw | grep '[a]pache' | awk '{print " -p " $2}' | \
xargs strace -o /tmp/strace-apache-proc.out

ps auxw | grep '[i]init_policy' | awk '{print " -p " $2}' | \
xargs strace -f -e trace=network -T -s 10000

strace -f -e trace=bind nc -l 80

strace -f -e trace=network nc -lu 80

kill -9 $(lsof -i :<port> | awk '{l=$2} END {print l}')

diff <(cd directory1 && find | sort) <(cd directory2 && find | sort)

diff <(cat /etc/passwd) <(cut -f2 /etc/passwd)

vimdiff file1 file2

vimdiff <(jq -S . A.json) <(jq -S . B.json)

d(){ vimdiff <(f $1) <(f $2);};f(){ hexdump -C $1 | cut -d' ' -f3- | tr -s ' ';}; d ~/bin1 ~/bin2

Save diffchar @ ~/.vim/plugins

Click F7 to switch between diff modes

Usefull vimdiff commands:

• qa to exit all windows
• :vertical resize 70 to resize window
• set window width Ctrl+W [N columns]+(Shift+)<\>

tail -f file | while read ; do echo "$(date +%T.%N) $REPLY" ; done

tail -10000 access_log | awk '{print $1}' | sort | uniq -c | sort -n | tail

tail -n 100 -f /path/to/logfile | grep "HTTP/[1-2].[0-1]\" [5]"

cd /
tar -czvpf /mnt/system$(date +%d%m%Y%s).tgz --directory=/ \
--exclude=proc/* --exclude=sys/* --exclude=dev/* --exclude=mnt/* .

cd /
tar cvpf /backup/snapshot-$(date +%d%m%Y%s).tgz --directory=/ \
--exclude=proc/* --exclude=sys/* --exclude=dev/* \
--exclude=mnt/* --exclude=tmp/* --use-compress-program=pigz .

dump -y -u -f /backup/system$(date +%d%m%Y%s).lzo /

cd /
restore -rf /backup/system$(date +%d%m%Y%s).lzo

cpulimit -p pid -l 50

pwdx <pid>

taskset -c 0 <command>

tr : '\n' <<<$PATH

chmod -R -x+X *

# 1:
cp /bin/ls chmod.01
cp /bin/chmod chmod.01
./chmod.01 700 file

# 2:
/bin/busybox chmod 0700 /bin/chmod

# 3:
setfacl --set u::rwx,g::---,o::--- /bin/chmod

who -b

[[ $(who -m | awk '{ print $1 }') == $(whoami) ]] || echo "You are su-ed to $(whoami)"

(last -x -f $(ls -1t /var/log/wtmp* | head -2 | tail -1); last -x -f /var/log/wtmp) | \
grep -A1 reboot | head -2 | grep -q shutdown && echo "Expected reboot" || echo "Panic reboot"

screen -d -m <command>

screen -r -d <pid>

### Record session
# 1)
script -t 2>~/session.time -a ~/session.log

# 2)
script --timing=session.time session.log

### Replay session
scriptreplay --timing=session.time session.log

du | \
sort -r -n | \
awk '{split("K M G",v); s=1; while($1>1024){$1/=1024; s++} print int($1)" "v[s]"\t"$2}' | \
head -n 20

while true ; do inotifywait -r -e MODIFY dir/ && ls dir/ ; done;

echo | openssl s_client -connect google.com:443 -showcerts

echo | openssl s_client -connect google.com:443 -showcerts -tlsextdebug -status

echo | openssl s_client -showcerts -servername google.com -connect google.com:443

openssl s_client -tls1_2 -connect google.com:443

openssl s_client -cipher 'AES128-SHA' -connect google.com:443

_host="example.com"

cat > req.in << __EOF__
HEAD / HTTP/1.1
Host: $_host
Connection: close
__EOF__

openssl s_client -connect ${_host}:443 -tls1_3 -sess_out session.pem -ign_eof < req.in
openssl s_client -connect ${_host}:443 -tls1_3 -sess_in session.pem -early_data req.in

# _len: 2048, 4096
( _fd="private.key" ; _len="2048" ; \
openssl genrsa -out ${_fd} ${_len} )

# _ciph: aes128, aes256
# _len: 2048, 4096
( _ciph="aes128" ; _fd="private.key" ; _len="2048" ; \
openssl genrsa -${_ciph} -out ${_fd} ${_len} )

( _fd="private.key" ; _fd_unp="private_unp.key" ; \
openssl rsa -in ${_fd} -out ${_fd_unp} )

# _ciph: aes128, aes256
( _ciph="aes128" ; _fd="private.key" ; _fd_pass="private_pass.key" ; \
openssl rsa -${_ciph} -in ${_fd} -out ${_fd_pass}

( _fd="private.key" ; \
openssl rsa -check -in ${_fd} )

( _fd="private.key" ; _fd_pub="public.key" ; \
openssl rsa -pubout -in ${_fd} -out ${_fd_pub} )

( _fd="private.key" ; _fd_csr="request.csr" ; _len="2048" ; \
openssl req -out ${_fd_csr} -new -newkey rsa:${_len} -nodes -keyout ${_fd} )

( _fd="private.key" ; _fd_csr="request.csr" ; \
openssl req -out ${_fd_csr} -new -key ${_fd} )

Where private.key is the existing private key. As you can see you do not generate this CSR from your certificate (public key). Also you do not generate the "same" CSR, just a new one to request a new certificate.

( _fd="private.key" ; _fd_csr="request.csr" ; _fd_crt="cert.crt" ; \
openssl x509 -x509toreq -in ${_fd_crt} -out ${_fd_csr} -signkey ${_fd} )

( _fd="private.key" ; _fd_csr="request.csr" ; \
openssl req -new -sha256 -key ${_fd} -out ${_fd_csr} \
-config <(
cat << __EOF__
[req]
default_bits        = 2048
default_md          = sha256
prompt              = no
distinguished_name  = dn
req_extensions      = req_ext

[ dn ]
C   = "<two-letter ISO abbreviation for your country>"
ST  = "<state or province where your organisation is legally located>"
L   = "<city where your organisation is legally located>"
O   = "<legal name of your organisation>"
OU  = "<section of the organisation>"
CN  = "<fully qualified domain name>"

[ req_ext ]
subjectAltName = @alt_names

[ alt_names ]
DNS.1 = <fully qualified domain name>
DNS.2 = <next domain>
DNS.3 = <next domain>
__EOF__
))

Other values in [ dn ]:

countryName            = "DE"                     # C=
stateOrProvinceName    = "Hessen"                 # ST=
localityName           = "Keller"                 # L=
postalCode             = "424242"                 # L/postalcode=
postalAddress          = "Keller"                 # L/postaladdress=
streetAddress          = "Crater 1621"            # L/street=
organizationName       = "apfelboymschule"        # O=
organizationalUnitName = "IT Department"          # OU=
commonName             = "example.com"            # CN=
emailAddress           = "[email protected]"  # CN/emailAddress=

Example of oids (you'll probably also have to make OpenSSL know about the new fields required for EV by adding the following under [new_oids]):

[req]
...
oid_section         = new_oids

[ new_oids ]
postalCode = 2.5.4.17
streetAddress = 2.5.4.9

Full example:

( _fd="private.key" ; _fd_csr="request.csr" ; \
openssl req -new -sha256 -key ${_fd} -out ${_fd_csr} \
-config <(
cat << __EOF__
[req]
default_bits        = 2048
default_md          = sha256
prompt              = no
distinguished_name  = dn
req_extensions      = req_ext
oid_section         = new_oids

[ new_oids ]
serialNumber = 2.5.4.5
streetAddress = 2.5.4.9
postalCode = 2.5.4.17
businessCategory = 2.5.4.15

[ dn ]
serialNumber=00001111
businessCategory=Private Organization
jurisdictionC=DE
C=DE
ST=Hessen
L=Keller
postalCode=424242
streetAddress=Crater 1621
O=AV Company
OU=IT
CN=example.com

[ req_ext ]
subjectAltName = @alt_names

[ alt_names ]
DNS.1 = example.com
__EOF__
))

For more information please look at these great explanations:

• RFC 5280
• How to create multidomain certificates using config files
• Generate a multi domains certificate using config files
• Your OpenSSL CSR command is out of date
• OpenSSL example configuration file
• Object Identifiers (OIDs)
• openssl objects.txt

openssl ecparam -list_curves

( _fd="private.key" ; \
openssl ec -in ${_fd} -noout -text )

# For x25519 only extracting public key
( _fd="private.key" ; _fd_pub="public.key" ; \
openssl pkey -in ${_fd} -pubout -out ${_fd_pub} )

# _curve: prime256v1, secp521r1, secp384r1
( _fd="private.key" ; _curve="prime256v1" ; \
openssl ecparam -out ${_fd} -name ${_curve} -genkey )

# _curve: X25519
( _fd="private.key" ; _curve="x25519" ; \
openssl genpkey -algorithm ${_curve} -out ${_fd} )

# _curve: prime256v1, secp521r1, secp384r1
( _fd="domain.com.key" ; _fd_csr="domain.com.csr" ; _curve="prime256v1" ; \
openssl ecparam -out ${_fd} -name ${_curve} -genkey ; \
openssl req -new -key ${_fd} -out ${_fd_csr} -sha256 )

# _len: 2048, 4096
( _fd="domain.key" ; _fd_out="domain.crt" ; _len="2048" ; _days="365" ; \
openssl req -newkey rsa:${_len} -nodes \
-keyout ${_fd} -x509 -days ${_days} -out ${_fd_out} )

# _len: 2048, 4096
( _fd="domain.key" ; _fd_out="domain.crt" ; _days="365" ; \
openssl req -key ${_fd} -nodes \
-x509 -days ${_days} -out ${_fd_out} )

# _len: 2048, 4096
( _fd="domain.key" ; _fd_csr="domain.csr" ; _fd_out="domain.crt" ; _days="365" ; \
openssl x509 -signkey ${_fd} -nodes \
-in ${_fd_csr} -req -days ${_days} -out ${_fd_out} )

( _dh_size="2048" ; \
openssl dhparam -out /etc/nginx/ssl/dhparam_${_dh_size}.pem "$_dh_size" )

openssl pkeyparam -in dhparam.pem -text

( _fd_pfx="cert.pfx" ; _fd_key="key.pem" ; \
openssl pkcs12 -in ${_fd_pfx} -nocerts -nodes -out ${_fd_key} )

( _fd_pfx="cert.pfx" ; _fd_pem="key_certs.pem" ; \
openssl pkcs12 -in ${_fd_pfx} -nodes -out ${_fd_pem} )

# PKCS#7 file doesn't include private keys.
( _fd_p7b="cert.p7b" ; _fd_pem="cert.pem" ; \
openssl pkcs7 -inform DER -outform PEM -in ${_fd_p7b} -print_certs > ${_fd_pem})
# or:
openssl pkcs7 -print_certs -in -in ${_fd_p7b} -out ${_fd_pem})

( _fd_der="cert.crt" ; _fd_pem="cert.pem" ; \
openssl x509 -in ${_fd_der} -inform der -outform pem -out ${_fd_pem} )

( _fd_der="cert.crt" ; _fd_pem="cert.pem" ; \
openssl x509 -in ${_fd_pem} -outform der -out ${_fd_der} )

( _fd="private.key" ; \
openssl rsa -noout -text -in ${_fd} )

# 1)
( _fd="public.key" ; \
openssl pkey -noout -text -pubin -in ${_fd} )

# 2)
( _fd="private.key" ; \
openssl rsa -inform PEM -noout -in ${_fd} &> /dev/null ; \
if [ $? = 0 ] ; then echo -en "OK\n" ; fi )

( _fd="certificate.crt" ; # format: pem, cer, crt \
openssl x509 -noout -text -in ${_fd} )

( _fd_csr="request.csr" ; \
openssl req -text -noout -in ${_fd_csr} )

(openssl rsa -noout -modulus -in private.key | openssl md5 ; \
openssl x509 -noout -modulus -in certificate.crt | openssl md5) | uniq

(openssl rsa -noout -modulus -in private.key | openssl md5 ; \
openssl req -noout -modulus -in request.csr | openssl md5) | uniq

shred -vfuz -n 10 file
shred --verbose --random-source=/dev/urandom -n 1 /dev/sda

scrub -p dod /dev/sda
scrub -p dod -r file

badblocks -s -w -t random -v /dev/sda
badblocks -c 10240 -s -w -t random -v /dev/sda

srm -vz /tmp/file
sfill -vz /local
sdmem -v
swapoff /dev/sda5 && sswap -vz /dev/sda5

dd <dd_params> status=progress
watch --interval 5 killall -USR1 dd

echo "string" | dd of=filename

gpg --export --armor "<username>" > username.pkey

• --export - export all keys from all keyrings or specific key
• -a|--armor - create ASCII armored output

gpg -e -r "<username>" dump.sql

• -e|--encrypt - encrypt data
• -r|--recipient - encrypt for specific

gpg -o dump.sql -d dump.sql.gpg

• -o|--output - use as output file
• -d|--decrypt - decrypt data (default)

gpg --keyserver hkp://keyserver.ubuntu.com --search-keys "<username>"

• --keyserver - set specific key server
• --search-keys - search for keys on a key server

gpg --batch --list-packets archive.gpg
gpg2 --batch --list-packets archive.gpg

exec /sbin/init 6

exec /sbin/init

readlink -f /proc/<PID>/cwd

readlink -f /proc/<PID>/exe

curl -Iks https://www.google.com

• -I - show response headers only
• -k - insecure connection when using ssl
• -s - silent mode (not display body)

curl -Iks --location -X GET -A "x-agent" https://www.google.com

• --location - follow redirects
• -X - set method
• -A - set user-agent

curl -Iks --location -X GET -A "x-agent" --proxy http://127.0.0.1:16379 https://www.google.com

• --proxy [socks5://|http://] - set proxy server

curl -o file.pdf -C - https://example.com/Aiju2goo0Ja2.pdf

• -o - write output to file
• -C - resume the transfer

curl ipinfo.io
curl ipinfo.io/ip
curl icanhazip.com
curl ifconfig.me/ip ; echo

# URL sequence substitution with a dummy query string:
curl -ks https://example.com/?[1-20]

# With shell 'for' loop:
for i in {1..20} ; do curl -ks https://example.com/ ; done

### Set domains and external dns servers.
_domain_list=(google.com) ; _dns_list=("8.8.8.8" "1.1.1.1")

for _domain in "${_domain_list[@]}" ; do

  printf '=%.0s' {1..48}

  echo

  printf "[\\e[1;32m+\\e[m] resolve: %s\\n" "$_domain"

  for _dns in "${_dns_list[@]}" ; do

    # Resolve domain.
    host "${_domain}" "${_dns}"

    echo

  done

  for _proto in http https ; do

    printf "[\\e[1;32m+\\e[m] trace + headers: %s://%s\\n" "$_proto" "$_domain"

    # Get trace and http headers.
    curl -Iks -A "x-agent" --location "${_proto}://${_domain}"

    echo

  done

done

unset _domain_list _dns_list

http -p Hh https://www.google.com

• -p - print request and response headers
  • H - request headers
  • B - request body
  • h - response headers
  • b - response body

http -p Hh https://www.google.com --follow --verify no

• -F, --follow - follow redirects
• --verify no - skip SSL verification

http -p Hh https://www.google.com --follow --verify no \
--proxy http:http://127.0.0.1:16379

• --proxy [http:] - set proxy server

# Supported escape sequences:
~.  - terminate connection (and any multiplexed sessions)
~B  - send a BREAK to the remote system
~C  - open a command line
~R  - Request rekey (SSH protocol 2 only)
~^Z - suspend ssh
~#  - list forwarded connections
~&  - background ssh (when waiting for connections to terminate)
~?  - this message
~~  - send the escape character by typing it twice

ssh user@host cat /path/to/remotefile | diff /path/to/localfile -

ssh -t reachable_host ssh unreachable_host

cat > cmd.txt << __EOF__
cat /etc/hosts
__EOF__

ssh host -l user $(<cmd.txt)

ssh-keygen -y -f ~/.ssh/id_rsa

ssh-keygen -l -f .ssh/known_hosts

ssh -o PreferredAuthentications=password -o PubkeyAuthentication=no user@remote_host

ssh -o PreferredAuthentications=publickey -o PubkeyAuthentication=yes -i id_rsa user@remote_host

function _ssh_sesslog() {

  _sesdir="<path/to/session/logs>"

  mkdir -p "${_sesdir}" && \
  ssh $@ 2>&1 | tee -a "${_sesdir}/$(date +%Y%m%d).log"

}

# Alias:
alias ssh='_ssh_sesslog'

### Delete all of ssh-agent's keys.
function _scl() {

  /usr/bin/keychain --clear

}

### Add key to keychain.
function _scg() {

  /usr/bin/keychain /path/to/private-key
  source "$HOME/.keychain/$HOSTNAME-sh"

}

ssh -tt user@host bash

Example 1:

# Forwarding our local 2250 port to nmap.org:443 from localhost through localhost
host1> ssh -L 2250:nmap.org:443 localhost

# Connect to the service:
host1> curl -Iks --location -X GET https://localhost:2250

Example 2:

# Forwarding our local 9051 port to db.d.x:5432 from localhost through node.d.y
host1> ssh -nNT -L 9051:db.d.x:5432 node.d.y

# Connect to the service:
host1> psql -U db_user -d db_dev -p 9051 -h localhost

• -n - redirects stdin from /dev/null
• -N - do not execute a remote command
• -T - disable pseudo-terminal allocation

# Forwarding our local 9051 port to db.d.x:5432 from host2 through node.d.y
host1> ssh -nNT -R 9051:db.d.x:5432 node.d.y

# Connect to the service:
host2> psql -U postgres -d postgres -p 8000 -h localhost

timeout 1 bash -c "</dev/<proto>/<host>/<port>" >/dev/null 2>&1 ; echo $?

• <proto - set protocol (tcp/udp)
• <host> - set remote host
• <port> - set destination port

exec 5<>/dev/tcp/<host>/<port>; cat <&5 & cat >&5; exec 5>&-

tcpdump -ne -i eth0 -Q in host 192.168.252.1 and port 443

• -n - don't convert addresses (-nn will not resolve hostnames or ports)
• -e - print the link-level headers
• -i [iface|any] - set interface
• -Q|-D [in|out|inout] - choose send/receive direction (-D - for old tcpdump versions)
• host [ip|hostname] - set host, also [host not]
• [and|or] - set logic
• port [1-65535] - set port number, also [port not]

tcpdump -ne -i eth0 -Q in host 192.168.252.1 and port 443 -c 5 -w tcpdump.pcap

• -c [num] - capture only num number of packets
• -w [filename] - write packets to file, -r [filename] - reading from file

tcpdump -nei eth0 icmp

tcpdump -nei eth0 tcp port 22 -vv -X | egrep "TCP|UDP"

tcpdump -i eth0 -A -s0 port 443

tcpdump -i eth0 port 80 -X | sed -n -e '/username/,/=ldap/ p'

tcpdump -i eth0  port http -l -A | egrep -i \
'pass=|pwd=|log=|login=|user=|username=|pw=|passw=|passwd=|password=|pass:|user:|username:|password:|login:|pass |user ' \
--color=auto --line-buffered -B20

tcpdump -ei eth0 -nn -A -s1500 -l | grep "User-Agent:"

tcpdump -ei eth0 -s 0 -A -vv \
'tcp[((tcp[12:1] & 0xf0) >> 2):4] = 0x47455420' or 'tcp[((tcp[12:1] & 0xf0) >> 2):4] = 0x504f5354'

or simply:

tcpdump -ei eth0 -s 0 -v -n -l | egrep -i "POST /|GET /|Host:"

tcpdump -ei eth0 -w /tmp/capture-%H.pcap -G 3600 -C 200

• -G <num> - pcap will be created every <num> seconds
• -C <size> - close the current pcap and open a new one if is larger than <size>

tcpdump -ei enp0s25 -nnn -t -c 200 | cut -f 1,2,3,4 -d '.' | sort | uniq -c | sort -nr | head -n 20

tcpdump -nei eth0 'not (src net (10 or 172.16/12 or 192.168/16) and dst net (10 or 172.16/12 or 192.168/16))'

while true ; do tcpick -a -C -r dump.pcap ; sleep 2 ; clear ; done

ngrep -d eth0 "www.domain.com" port 443

• -d [iface|any] - set interface
• [domain] - set hostname
• port [1-65535] - set port number

ngrep -d eth0 "www.domain.com" src host 10.240.20.2 and port 443

• (host [ip|hostname]) - filter by ip or hostname
• (port [1-65535]) - filter by port number

ngrep -d eth0 -qt -O ngrep.pcap "www.domain.com" port 443

• -q - quiet mode (only payloads)
• -t - added timestamps
• -O [filename] - save output to file, -I [filename] - reading from file

ngrep -d eth0 -qt 'HTTP' 'tcp'

• HTTP - show http headers
• tcp|udp - set protocol
• [src|dst] host [ip|hostname] - set direction for specific node

ngrep -l -q -d eth0 -i "User-Agent: curl*"

• -l - stdout line buffered
• -i - case-insensitive search

hping3 -V -p 80 -s 5050 <scan_type> www.google.com

• -V|--verbose - verbose mode
• -p|--destport - set destination port
• -s|--baseport - set source port
• <scan_type> - set scan type
  • -F|--fin - set FIN flag, port open if no reply
  • -S|--syn - set SYN flag
  • -P|--push - set PUSH flag
  • -A|--ack - set ACK flag (use when ping is blocked, RST response back if the port is open)
  • -U|--urg - set URG flag
  • -Y|--ymas - set Y unused flag (0x80 - nullscan), port open if no reply
  • -M 0 -UPF - set TCP sequence number and scan type (URG+PUSH+FIN), port open if no reply

hping3 -V -c 1 -1 -C 8 www.google.com

• -c [num] - packet count
• -1 - set ICMP mode
• -C|--icmptype [icmp-num] - set icmp type (default icmp-echo = 8)

hping3 -V -c 1000000 -d 120 -S -w 64 -p 80 --flood --rand-source <remote_host>

• --flood - sent packets as fast as possible (don't show replies)
• --rand-source - random source address mode
• -d --data - data size
• -w|--win - winsize (default 64)

nmap -sP 192.168.0.0/24

nmap -F --open 192.168.0.0/24

nmap -p 1-65535 -sV -sS -T4 192.168.0.0/24

nmap -p80,443 192.168.0.0/24 -oG - | nikto.pl -h -

# Set variables:
_hosts="192.168.250.10"
_ports="80,443"

# Set Nmap NSE scripts stack:
_nmap_nse_scripts="+dns-brute,\
                   +http-auth-finder,\
                   +http-chrono,\
                   +http-cookie-flags,\
                   +http-cors,\
                   +http-cross-domain-policy,\
                   +http-csrf,\
                   +http-dombased-xss,\
                   +http-enum,\
                   +http-errors,\
                   +http-git,\
                   +http-grep,\
                   +http-internal-ip-disclosure,\
                   +http-jsonp-detection,\
                   +http-malware-host,\
                   +http-methods,\
                   +http-passwd,\
                   +http-phpself-xss,\
                   +http-php-version,\
                   +http-robots.txt,\
                   +http-sitemap-generator,\
                   +http-shellshock,\
                   +http-stored-xss,\
                   +http-title,\
                   +http-unsafe-output-escaping,\
                   +http-useragent-tester,\
                   +http-vhosts,\
                   +http-waf-detect,\
                   +http-waf-fingerprint,\
                   +http-xssed,\
                   +traceroute-geolocation.nse,\
                   +ssl-enum-ciphers,\
                   +whois-domain,\
                   +whois-ip"

# Set Nmap NSE script params:
_nmap_nse_scripts_args="dns-brute.domain=${_hosts},http-cross-domain-policy.domain-lookup=true,"
_nmap_nse_scripts_args+="http-waf-detect.aggro,http-waf-detect.detectBodyChanges,"
_nmap_nse_scripts_args+="http-waf-fingerprint.intensive=1"

# Perform scan:
nmap --script="$_nmap_nse_scripts" --script-args="$_nmap_nse_scripts_args" -p "$_ports" "$_hosts"

nc -kl 5000

• -l - listen for an incoming connection
• -k - listening after client has disconnected
• >filename.out - save receive data to file (optional)

nc 192.168.0.1 5051 < filename.in

• < filename.in - send data to remote host

nc -vz 10.240.30.3 5000

• -v - verbose output
• -z - scan for listening daemons

nc -vzu 10.240.30.3 1-65535

• -u - scan only udp ports

server> nc -l 5000 | tar xzvfp -
client> tar czvfp - /path/to/dir | nc 10.240.30.3 5000

# 1)
server> nc -l 5000 -e /bin/bash
client> nc 10.240.30.3 5000

# 2)
server> rm -f /tmp/f; mkfifo /tmp/f
server> cat /tmp/f | /bin/bash -i 2>&1 | nc -l 127.0.0.1 5000 > /tmp/f
client> nc 10.240.30.3 5000

while true ; do nc -l 5000 | tar -xvf - ; done

while true ; do nc -l -p 1500 -c 'echo -e "HTTP/1.1 200 OK\n\n $(date)"' ; done

Restarts web server after each request - remove while condition for only single connection.

cat > index.html << __EOF__
<!doctype html>
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
        <title></title>
        <meta name="description" content="">
        <meta name="viewport" content="width=device-width, initial-scale=1">
    </head>
    <body>

    <p>

      Hello! It's a site.

    </p>

    </body>
</html>
__EOF__

server> while : ; do \
(echo -ne "HTTP/1.1 200 OK\r\nContent-Length: $(wc -c <index.html)\r\n\r\n" ; cat index.html;) | \
nc -l -p 5000 \
; done

• -p - port number

#!/usr/bin/env bash

if [[ $# != 2 ]] ; then
  printf "%s\\n" \
         "usage: ./nc-proxy listen-port bk_host:bk_port"
fi

_listen_port="$1"
_bk_host=$(echo "$2" | cut -d ":" -f1)
_bk_port=$(echo "$2" | cut -d ":" -f2)

printf "  lport: %s\\nbk_host: %s\\nbk_port: %s\\n\\n" \
       "$_listen_port" "$_bk_host" "$_bk_port"

_tmp=$(mktemp -d)
_back="$_tmp/pipe.back"
_sent="$_tmp/pipe.sent"
_recv="$_tmp/pipe.recv"

trap 'rm -rf "$_tmp"' EXIT

mkfifo -m 0600 "$_back" "$_sent" "$_recv"

sed "s/^/=> /" <"$_sent" &
sed "s/^/<=  /" <"$_recv" &

nc -l -p "$_listen_port" <"$_back" | \
tee "$_sent" | \
nc "$_bk_host" "$_bk_port" | \
tee "$_recv" >"$_back"