VPN & Firewall
Learn how VPNs encrypt your internet traffic and how firewalls protect networks from unauthorized access.
What is a VPN?
A VPN (Virtual Private Network) creates an encrypted "tunnel" between your device and a VPN server. All your internet traffic flows through this tunnel, hiding your activity from your ISP, hackers on public Wi-Fi, and websites tracking your real IP address.
How a VPN Works
- Your device connects to a VPN server.
- Your traffic is encrypted before leaving your device.
- The VPN server decrypts your traffic and sends it to the destination.
- Responses are encrypted by the VPN server and sent back to you.
- Websites see the VPN server's IP, not yours.
When to Use a VPN
- Public Wi-Fi — Cafés, airports, hotels. VPNs protect against eavesdroppers.
- Privacy — Prevent ISPs and advertisers from tracking your browsing.
- Geo-restrictions — Access content that's blocked in your region.
- Remote Work — Securely access company resources from home.
What is a Firewall?
A firewall is a network security device (hardware or software) that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It acts as a barrier between trusted internal networks and untrusted external networks.
Types of Firewalls
- Packet Filtering — Inspects packets and blocks/allows based on IP, port, and protocol rules. Fast but limited.
- Stateful Inspection — Tracks active connections and makes decisions based on the state of the traffic. More intelligent.
- Application Layer (Proxy) Firewall — Inspects traffic at the application level. Most thorough protection.
- Next-Generation Firewall (NGFW) — Combines traditional firewall + intrusion prevention, deep packet inspection, and application awareness.
Firewall Rules
Firewalls work by allowing or blocking traffic based on rules. A good default rule is "deny all, permit by exception" — block everything and only allow what is explicitly needed.
What's Next?
Learn how cryptographic protocols secure your connections in Cryptography & Encryption, protect against device-level threats in Viruses & Malware, or explore Cyber Security as a whole discipline.