Your port number isn't a secret—it's a trivia question any scanner answers in seconds. Here's what actually protects your systems.
Every open port runs code that parses untrusted input—and parsing is where vulnerabilities live. Here's how to find what's listening and shut down what you don't need.
Open, closed, or filtered—every port tells a story. Here's how to read it using command-line tools on any operating system, plus how to test your own servers from the outside world.
Port knocking hides services behind a secret sequence of connection attempts. Critics call it security theater. But an attacker can't exploit what they can't reach—and that's not obscurity, it's geometry.
Every device on the Internet is being scanned constantly. Understanding how port scanning works—TCP, SYN, and UDP techniques—helps you see your network the way attackers do.
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