How to Build a Secure Serverless Port Scanner in Node.js (and Prevent SSRF)

Every network engineer and systems developer needs to verify connection ports. Whether you're debugging why a remote database connection is failing, checking if an SSH daemon is running, or auditing active firewall rules, programmatically checking TCP ports is a core developer task. However, writing a port scanner in Node.js comes with a massive, critical security risk: Server-Side Request Forgery (SSRF). If you allow users to pass a host parameter directly into a network socket connection, a