Security Sheets
In-depth guides to protect your digital life
Developer pick: Best Free IP Geolocation API (2026) — a source-verified roundup of 7 free IP APIs.
Curl What Is My IP: One-Liners, JSON Output, and Every Endpoint Compared (2026)
Run "curl hackmyip.com" to print your public IP in the terminal, then see every major command-line IP endpoint compared — ifconfig.me, icanhazip, ipify, Amazon, ident.me and more, each checked July 2026 — plus JSON output, IPv4 vs IPv6 behavior, and DNS-based lookups with dig.
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Free IP API With No Key: The Keyless Options Compared (2026)
A no-fluff comparison of the free IP geolocation APIs that need no API key — HackMyIP, ip-api.com, ipwho.is, geojs.io and more — by free-tier limit, HTTPS-on-free, and commercial-use terms, each checked July 2026. Plus how to use the free keyless HackMyIP API over plain HTTPS GET.
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A curl IP Geolocation One-Liner (No API Key)
Get IP geolocation from one curl command — your own IP or any IP — with no API key. Copy-paste one-liners for the terminal, plus how to parse the city and country with jq.
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What Is My User Agent? (Browser and curl)
Your User-Agent is the string your browser or HTTP client sends to identify itself. See what yours says, why curl and a browser differ, and how to check it from the terminal or the browser.
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How I Made My Privacy Site Recommendable by ChatGPT (and Got Merged into public-apis the Same Week)
A 6-file playbook for making any site discoverable to AI agents. Real code, real GA numbers from hackmyip.com, including how a one-line PR to public-apis (437k stars) compounded with the LLM-readiness work.
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What Can Someone Do With Your IP Address? (2026)
With your IP address someone can find your approximate city and ISP, launch a DDoS attack, or scan for open ports — but they cannot hack your accounts, read your browsing history, or pinpoint your home. The honest can-vs-cannot breakdown, with a quick-reference table and no fear-mongering.
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Is Your VPN Actually Working? 5 Tests to Find Out
Five practical tests to verify your VPN is truly protecting your privacy and not leaking your real IP address.
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Browser Fingerprinting: How Sites Track You Without Cookies
Understand how browser fingerprinting works, why it is harder to block than cookies, and how to reduce your digital fingerprint.
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How to Change Your IP Address (5 Methods)
Five practical methods to change your IP address for privacy, security, or troubleshooting purposes.
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Public vs Private IP: What Is the Difference?
Understand the difference between public and private IP addresses, how NAT works, and why both matter for your network.
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DNS Leak: The Silent Privacy Killer
What DNS leaks are, how they expose your browsing history even with a VPN, and how to fix them.
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WebRTC Leak: How Your VPN Gets Bypassed
How WebRTC leaks expose your real IP address even when using a VPN, and how to prevent them in every browser.
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What Are Open Ports and Why Should You Care?
Learn what open ports are, how attackers exploit them, and how to secure your network by closing unnecessary ports.
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Your ISP Knows Everything: Here Is What They See
Everything your Internet Service Provider can see about your online activity and how to limit their surveillance.
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WiFi Security Checklist: Is Your Home Network Safe?
A comprehensive checklist to secure your home WiFi network against common attacks and vulnerabilities.
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VPN vs Proxy: Which One Actually Protects You?
Understand the real differences between VPNs and proxies, and find out which one actually secures your traffic.
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7 Ways Websites Track You Online
Discover the seven most common tracking techniques websites use to follow you across the internet, and what you can do about each one.
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Tor Browser: How It Works and When to Use It
Learn how the Tor network routes your traffic through multiple relays for anonymity, and when Tor is the right tool for the job.
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What Is a VPN and How Does It Work?
A straightforward explanation of how VPNs work, what they protect, and what they do not, with no marketing fluff.
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Static vs Dynamic IP: Which One Do You Have?
Learn the difference between static and dynamic IP addresses, how to find out which type you have, and why it matters.
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HTTPS Explained: Why That Padlock Matters
Understand what HTTPS actually does, how TLS encryption works, and why the padlock icon in your browser is more important than you think.
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Incognito Mode: What It Actually Hides (and What It Does Not)
The truth about private browsing mode: what it protects, what it ignores, and why you are not as invisible as you think.
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Two-Factor Authentication: Your Best Defense Against Getting Owned
Why two-factor authentication is the single most effective thing you can do for account security, and which 2FA methods to use.
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How to Spot a Phishing Attack Before It Spots You
Learn the telltale signs of phishing emails, fake websites, and social engineering attacks so you never take the bait.
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Password Security: Why P@ssw0rd123 Will Not Save You
The reality of password security in 2024: why common tricks fail, how passwords get cracked, and what actually works.
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Best Free VPN Alternatives in 2026
Comparing the best free VPN options, their limitations, and when you should pay for a premium VPN instead.
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How to Check if Your VPN Is Working on iPhone
Step-by-step guide to verify your VPN connection on iPhone and iPad. Test for IP leaks, DNS leaks, and WebRTC leaks on iOS.
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What Is an IP Address? Everything You Need to Know
A complete beginner guide to IP addresses: what they are, how they work, IPv4 vs IPv6, public vs private, and why your IP matters.
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5 Ways to Hide Your IP Address in 2026
Five proven methods to hide your IP address for privacy, security, and anonymity. From VPNs to Tor to smart DNS.
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Internet Speed Test: How It Works and What the Numbers Mean
Understand download speed, upload speed, latency, and jitter. Learn what affects your speed test results and how to improve them.
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How to Find Your IP Address on iPhone (iOS 17/18)
Step-by-step guide to finding your public and private IP address on any iPhone or iPad. Three fast methods explained.
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How to Find Your IP Address on Windows 10 & 11
Find your public and private IP address on Windows using Settings, Command Prompt, or PowerShell. Quick step-by-step guide.
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How to Find Your IP Address on Mac (macOS)
Find your public and private IP address on Mac using System Settings, Terminal, or the quickest online method.
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How to Find Your IP Address on Android
Find your public and private IP address on any Android phone. Quick guide for Samsung, Pixel, and all Android devices.
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How to Find Your Router IP Address (Default Gateway)
Find your router IP address on Windows, Mac, iPhone, and Android. Access your router admin panel to change settings.
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IPv4 vs IPv6: What Is the Difference and Why It Matters
Understand the differences between IPv4 and IPv6 addresses, why IPv6 exists, and how to check which version you are using.
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Have I Been Hacked? 7 Warning Signs and What to Do
How to tell if your accounts have been compromised. Learn the warning signs of a hacked account and the steps to take immediately.
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Best DNS Servers 2026: Speed, Privacy and Security Compared
Compare the best DNS servers of 2026: Cloudflare 1.1.1.1, Google 8.8.8.8, Quad9, AdGuard DNS, NextDNS, ControlD, Mullvad and DNS4EU — IPs and logging policies verified against each provider's docs, plus a live latency test you run from your own browser.
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Can You Be Tracked With a VPN? The Honest Answer
Find out if a VPN really makes you anonymous online. What VPNs protect against, what they don't, and how you can still be tracked.
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How to Check If Someone Is Using Your WiFi
Find out who is connected to your WiFi network. Detect unauthorized devices and secure your home network from intruders.
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Email Breach Check: How to Know If Your Data Was Leaked
Learn how to check if your email was exposed in a data breach, what data may have been stolen, and how to protect yourself after a breach.
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How to Find Someone's IP Address (5 Legal Methods)
Learn how to find someone's IP address using legal methods. Email headers, website analytics, chat apps, and more — with privacy considerations.
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Is Tor Browser Safe? What It Hides and What It Doesn't
Is Tor Browser safe to use? Learn what Tor actually protects, its limitations, and how to use it properly for privacy.
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How to Tell If Your Router Has Been Hacked (8 Warning Signs)
Learn the warning signs of a hacked router, how to check if your router is compromised, and steps to fix and prevent router hacking.
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Is My IP Blacklisted? How to Check and Fix It
Check if your IP address is on a spam blacklist. Learn why IPs get blacklisted and how to remove yours from blacklists.
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Free Privacy API: IP Lookup, Email Breach Check, VPN Detection (No Key)
Use the free HackMyIP API for IP geolocation, email breach checking, VPN detection, and privacy scoring. No API key required. JSON responses with CORS.
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Have I Been Pwned Alternatives: What Still Works in 2026
Every major Have I Been Pwned alternative verified in July 2026: which breach checkers are still free, what each one searches, and which tools shut down.
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What Does Incognito Mode Actually Hide? The Full Truth
Incognito mode hides less than you think. Learn what private browsing actually protects, what it does not, and how to get real privacy online.
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How to Check If Your VPN Is Actually Working (4 Quick Tests)
Is your VPN really protecting you? Run these 4 quick tests to verify your IP is hidden, DNS is not leaking, and WebRTC is not exposing your real address.
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What Is My IP Address and Why Does It Matter? Complete Guide
Learn what an IP address is, how to find yours, what it reveals about you, and how to protect it. The complete beginner guide to IP addresses.
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Free Dark Web Monitoring: How to Check If Your Data Is Exposed
Learn how to monitor the dark web for your personal data for free. Check if your email, passwords, or personal information have been leaked in data breaches.
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How to Create a Strong Password in 2026 (Complete Guide)
Learn how to create a strong password that hackers cannot crack. Step-by-step guide with examples, best practices, and free tools to test your password strength.
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Do You Need a Password Manager? The Complete Guide
Everything you need to know about password managers: how they work, whether they are safe, free vs paid options, and how to choose the right one for you.
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The 50 Most Common Passwords in 2026 (And Why They Are Dangerous)
See the most common passwords people still use in 2026. Learn why these passwords get cracked instantly and how to replace them with secure alternatives.
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Two-Factor Authentication (2FA): What It Is and Why You Need It
A complete guide to two-factor authentication. Learn what 2FA is, how it works, which types are most secure, and how to enable it on your accounts today.
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How Password Strength Checkers Work (And Can You Trust Them?)
Learn how password strength checkers measure your password security. Understand the algorithms, scoring systems, and whether it is safe to type your password into them.
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Is My Phone Hacked? 10 Warning Signs and How to Fix It
Learn the 10 warning signs that your phone may be hacked, from battery drain to strange texts. Step-by-step guide to check and fix a compromised phone.
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What Is a Data Breach? How It Happens and How to Protect Yourself
Understand what a data breach is, how companies get hacked, what data gets exposed, and the practical steps you can take to protect yourself right now.
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How to Stop Being Tracked Online: Complete Privacy Guide
A complete guide to stopping online tracking. Learn how websites, advertisers, and ISPs track you and the practical tools to protect your privacy.
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What Is Your Digital Footprint and Why Should You Care?
Learn what a digital footprint is, how it is created, why it matters for your privacy and security, and practical steps to reduce and manage it.
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How to Check If an Email Is Safe Before Opening It
Learn how to identify phishing emails, check suspicious senders, and verify if an email is safe. Practical steps to protect yourself from email scams.
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Best Free VPNs in 2026: Which Ones Are Actually Safe?
A honest look at free VPN services in 2026. Learn which ones protect your privacy and which ones sell your data.
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How to Check If Your Phone Is Hacked (10 Warning Signs)
Learn the 10 warning signs that your phone may be compromised and what to do about it immediately.
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VPN Speed vs Security: How to Get Both in 2026
Learn how to optimize your VPN for both speed and security. Understand protocols, server selection, and configuration tips.
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How to Stop Websites from Tracking You Online
Practical steps to reduce online tracking from advertisers, data brokers, and websites in 2026.
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Public WiFi Dangers: How Hackers Steal Your Data at Coffee Shops
Learn how attackers exploit public WiFi networks and what you can do to stay safe on shared connections.
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Credential Stuffing: Why Reusing Passwords Gets You Hacked
Understand how credential stuffing attacks work and why password reuse is the biggest security mistake you can make.
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SIM Swap Attacks: How Hackers Steal Your Phone Number
Learn how SIM swap attacks work, why they bypass SMS-based security, and how to protect your phone number from being stolen.
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Dark Web Monitoring: How to Check If Your Data Is Exposed
Learn how dark web monitoring works and how to check if your personal data is being sold on underground markets.
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IP Address Security: What Hackers Can Do With Your IP
Understand the real security risks of IP address exposure and practical steps to protect yourself.
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How to Spot Phishing Emails and Fake Websites
Learn to identify phishing attempts with practical examples of fake emails, spoofed websites, and social engineering tactics.
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HackMyIP vs WhatIsMyIPAddress: Full Comparison (2026)
Detailed comparison of HackMyIP and WhatIsMyIPAddress.com. Features, tools, privacy, speed, and which one is better for checking your IP.
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HackMyIP vs IPLeak.net: Which Finds More Leaks? (2026)
Comparing HackMyIP and IPLeak.net for VPN leak testing. DNS leaks, WebRTC leaks, fingerprinting, and which tool catches more.
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HackMyIP vs BrowserLeaks.com: Fingerprinting Comparison (2026)
Comparing HackMyIP and BrowserLeaks for browser fingerprint testing. Canvas, WebGL, fonts, screen, and privacy analysis.
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HackMyIP vs DNSLeakTest.com: DNS Testing Comparison (2026)
Comparing HackMyIP and DNSLeakTest.com for DNS leak detection. Standard test, extended test, and additional privacy features.
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What Is a MAC Address? (And Can Websites See It?)
A MAC address is your device hardware ID. Learn what it is, how to find it, and whether websites or your ISP can track you with it.
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How Accurate Is IP Geolocation? How It Works and Why It Is Often Wrong
IP geolocation gets your country right over 99 percent of the time but misses your city far more often than marketing pages admit. How the databases are built, what the vendors themselves publish about accuracy, why your IP maps to the wrong place, and how to get it corrected.
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Static vs Dynamic IP: What Is the Difference and Which Do You Have?
Static IPs never change; dynamic IPs rotate. Learn the difference, how to tell which you have, and when you actually need a static IP.
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What Is a Default Gateway? (And How to Find Yours)
Your default gateway is the door between your device and the internet, usually your router. Learn what it is, why it is often 192.168.x.1, and how to find it.
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MAC Address vs IP Address: What Is the Difference?
MAC addresses identify hardware; IP addresses identify network location. Learn the difference, how they work together, and which one reveals you online.
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What Is a Subnet Mask? (And How to Read One)
A subnet mask splits an IP address into network and host parts. Learn what 255.255.255.0 means, how it maps to CIDR like /24, and how to calculate one.
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What Is a Firewall? How It Works
A firewall filters network traffic by rules on IP, port, and protocol. Learn how firewalls work, stateful vs stateless, hardware vs software, and whether you need one.
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What Is NAT (Network Address Translation)?
NAT lets many devices share one public IP address. Learn how NAT works, the difference between NAT and PAT, why your device has a private IP, and how NAT relates to a firewall.
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What Is DNS over HTTPS (DoH)?
DNS over HTTPS encrypts your DNS queries so no one on the network can read or tamper with them. Learn how DoH works, DoH vs DoT, what port it uses, and how to enable it.
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What Is an ASN (Autonomous System Number)?
An ASN identifies a network on the internet for BGP routing. Learn what an autonomous system number is, who assigns them, 16-bit vs 32-bit ASNs, and how to find the ASN for any IP.
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What Is Port Forwarding? How It Works
Port forwarding tells your router to send traffic on a specific port to one device behind it. Learn how port forwarding works, whether it is safe, and how it differs from port triggering.
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What Is a Proxy Server? How It Works
A proxy server is an intermediary that forwards your requests to the internet. Learn how proxy servers work, the difference between forward, reverse, and transparent proxies, and proxy vs VPN.
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What Is DHCP (Dynamic Host Configuration Protocol)?
DHCP automatically assigns an IP address and network settings to every device that joins a network. Learn how DHCP works, the DORA process, what a lease is, and DHCP vs a static IP.
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What Is BGP (Border Gateway Protocol)?
BGP is the routing protocol that holds the internet together by exchanging routes between networks. Learn how BGP works, BGP vs ASN, iBGP vs eBGP, and what BGP hijacking is.
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What Is a CDN (Content Delivery Network)?
A CDN is a network of servers that delivers websites from a location near each visitor. Learn how a CDN works, edge servers, CDN vs web host, and whether a CDN changes your IP.
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What Is a DNS Resolver? Recursive vs Authoritative
A DNS resolver turns a domain name into an IP address on your behalf. Learn recursive vs authoritative resolvers, the DNS resolution chain, caching and TTL, and public resolvers like 1.1.1.1.
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What Is a Router? How Home and Network Routers Work
A router forwards data between networks and is the hub of your home network. Learn what a router does, router vs modem, LAN vs WAN, the role of NAT and DHCP, and the default gateway.
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What Is a DDoS Attack? How It Works and How It Is Stopped
A DDoS attack floods a service with traffic from many sources to take it offline. Learn DoS vs DDoS, botnets, the three attack types, amplification, and how DDoS attacks are mitigated.
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TCP vs UDP: What Is the Difference?
TCP is reliable and ordered; UDP is fast and connectionless. Learn the difference between TCP and UDP, the three-way handshake, which is faster, what each is used for, and how ports work.
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What Is a UUID? Versions, Format, and How They Work
A UUID is a 128-bit Universally Unique Identifier. Learn the 8-4-4-4-12 format, what UUID versions 1, 4, and 7 mean, how to read the version and variant, and the nil and max UUIDs.
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What Is a Network Packet? Headers, Payload and Routing
A network packet is a small unit of data that travels across a network. Learn what a packet is, header vs payload, encapsulation, MTU and fragmentation, and how packets route hop by hop.
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What Is CGNAT (Carrier-Grade NAT)? Why You Share a Public IP
CGNAT lets your ISP share one public IPv4 address across many customers. Learn what the 100.64.0.0/10 range means, how to tell if you are behind CGNAT, why port forwarding breaks, and how to get a real public IP.
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IPv6 Privacy Extensions: Why Your IPv6 Address Keeps Changing
IPv6 privacy extensions give your device a rotating temporary address instead of one tied to your hardware. Learn why your IPv6 address changes, how SLAAC and EUI-64 once exposed your MAC, and how RFC 8981 fixes it.
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What Is APIPA (169.254.x.x)? The "No Internet" IP Address
A 169.254.x.x address means your device self-assigned an IPv4 link-local address because DHCP failed. Learn what APIPA is, why it means no internet, the 169.254.0.0/16 range, and how to fix it.
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What Is the Loopback Address (127.0.0.1 and localhost)?
The loopback address lets a computer send network traffic to itself. Learn what 127.0.0.1 and localhost mean, why the whole 127.0.0.0/8 range is loopback, the IPv6 ::1 address, and why developers use it.
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How to Read Email Headers (and Trace Where an Email Came From)
Learn how to open raw email headers in Gmail, Outlook and Apple Mail, read the Received chain from the bottom up, find the originating server and IP, and check SPF, DKIM and DMARC results.
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SPF, DKIM and DMARC Explained (How Email Authentication Works)
A plain-English guide to the three email authentication standards. Learn what SPF, DKIM and DMARC each prove, how they differ, and how to read an Authentication-Results header for pass or fail.
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What Is an Email Header? The Anatomy of Every Email
An email header is the metadata block at the top of every message. Learn what From, To, Subject, Message-ID, Received, Return-Path and Reply-To mean, the difference between the envelope and the header, and why headers can be spoofed.
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What Is SSL/TLS and How Does It Work?
How SSL/TLS encrypts the web: the TLS handshake, X.509 certificates and the CA chain of trust, SSL vs TLS naming, why valid TLS does not mean a safe site, and how to check a certificate.
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What Are HTTP Security Headers?
HTTP security headers tell browsers how to behave safely. Learn what Content-Security-Policy, HSTS, X-Frame-Options, X-Content-Type-Options, Referrer-Policy and Permissions-Policy do.
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Content Security Policy (CSP) Explained
A clear guide to Content Security Policy: how CSP works, common directives like default-src and script-src, how it blocks XSS, report-only mode, and common pitfalls.
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Canvas Fingerprinting: How Sites Track You by Drawing Invisible Images
How HTML5 canvas fingerprinting turns hidden text and shapes into a stable device ID that survives clearing cookies and incognito mode, and how to reduce it.
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AudioContext Fingerprinting: Tracking That Does Not Use Your Microphone
How Web Audio API fingerprinting measures tiny differences in how your device processes a synthetic signal to identify you, without ever touching the microphone.
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TLS Fingerprinting (JA3 and JA4): Tracking Below the Browser
How JA3 and JA4 fingerprint your TLS ClientHello to identify your client below the browser, why incognito mode and a VPN do not change it, and who uses it.
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Font Fingerprinting: How Your Installed Fonts Identify You
How websites detect which fonts are installed by measuring text size, why your font set is so identifying, and how the Font Access API and Tor Browser change the picture.
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User-Agent Client Hints Explained: The Replacement for the UA String
What User-Agent Client Hints are, how low-entropy and high-entropy hints differ, and what the shift from the broadcast User-Agent string means for fingerprinting.
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How to Read Traceroute Output: A Hop-by-Hop Guide
Learn how to read traceroute and tracert output: the hop numbers, the three RTT probes, hostnames, and how to find where latency actually jumps on the path.
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Traceroute vs Ping vs MTR: Which Tool to Use When
Ping checks reachability to one host, traceroute maps the full path via TTL, and MTR combines both with per-hop loss over time. Here is when to use each.
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What Is Reverse DNS? PTR Records Explained
Reverse DNS maps an IP back to a hostname using a PTR record in the in-addr.arpa or ip6.arpa zone. Learn who controls it and why mail servers check it.
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Why Is My Traceroute Timing Out? Reading the Star Hops
Traceroute showing asterisks usually means a router is not replying by policy, not a failure. Learn when timeouts are benign and when they signal a real problem.
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Why Is My IP Address Flagged as a Bot or VPN? (2026)
Your IP gets flagged as a bot, VPN, or proxy when it has a poor reputation — usually because it is a shared, datacenter, or recently abused address. Here is why it happens and how to check and fix your IP reputation.
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What Is an IP Reputation Score and How Do You Check It? (2026)
An IP reputation score rates how trustworthy your IP address looks to websites and anti-fraud systems, based on its type, history, and blacklist status. Learn what drives the score and how to check yours for free.
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Why Do Websites Keep Blocking Me or Showing CAPTCHAs? (2026)
Websites block you or show endless CAPTCHAs when your IP address looks risky — usually a VPN, datacenter, shared, or blacklisted IP. Learn the real causes and how to stop the blocks.
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What Is a Privacy Badge? Free Trust Seals for Your Website or README
A privacy badge is a small embeddable image that signals a website or project takes privacy seriously. Learn the difference between trust badges and trust seals, how to add one to a site or GitHub README, and the honest answer on whether badges help SEO.
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