Skip to main content
Cactus
  • Home
  • Start Here
  • Tools
    • All tools

    • Links & messages
    • Check a Link
    • Check a QR Code
    • Check an Email
    • Scam Text Checker
    • Batch Check

    • Site & domain security
    • SSL/TLS Check
    • Email Auth
    • Security Headers
    • Look-alike Domains
    • Certificate Search
    • IP Reputation

    • Your accounts
    • Password Check
  • Resources
    • I've Been Scammed
    • Scam of the Week
    • Learn
    • Security Glossary
    • Our Mission
    • How it works
    • Comparisons
  • Safe Software
Buy me a coffee
EN | FR

← Back to the glossary

Firewall

A barrier - software or hardware - that controls which network traffic is allowed in or out of your device or network, blocking unwanted connections.

Related terms

  • HTTPS
  • Identity theft
  • Malware
  • Multi-factor authentication (MFA)
  • Passphrase
  • Password manager
Cactus

Free, bilingual security tools to help you spot scams and stay safe online.

☕ Buy me a coffee

About

  • Our Mission
  • How it works
  • Comparisons
  • Trust & Security
  • Status
  • API

Resources

  • All tools
  • Start Here
  • Learn
  • Security Glossary
  • Scam of the Week
  • Safe Software
  • I've Been Scammed
  • Link checker widget
  • Newsletter

Legal

  • Privacy
  • Terms
  • Acceptable Use
© 2026 - Cactus Security