Learn

How localhost tunnels work and what they expose, and why dev servers turn away addresses they don't know. Explained from the code, with sources.

• What is a localhost tunnel, and is it safe?

  A tunnel gives one port on your computer a public address, over a connection your computer opens. How it works, and what it does and doesn't expose.

• Why dev servers block unknown hosts

  Vite, Next.js, Django and Rails turn away addresses they don't know, to stop DNS rebinding. How the attack works, the CVEs behind it, and the safe fixes.

For step-by-step help with a task, see the guides.