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Firewalls
Network security devices that filter traffic based on rules. They act as a barrier between trusted and untrusted networks.
- Packet-filtering — inspects headers
- Stateful — tracks connection state
- Next-gen (NGFW) — adds deep packet inspection
- WAF — protects web applications
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Encryption
Transforms data into an unreadable form so only authorized parties can access it. Essential for data in transit and at rest.
- Symmetric — same key (AES)
- Asymmetric — key pairs (RSA, ECC)
- TLS/SSL — secures web traffic
- Hashing — integrity (SHA-256)
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Multi-Factor Authentication
Requires two or more verification factors, dramatically reducing the risk of compromised passwords.
- Something you know — password
- Something you have — token, phone
- Something you are — biometrics
- Authenticator apps beat SMS codes
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Network Segmentation
Divides a network into zones to limit lateral movement and contain breaches to a small area.
- VLANs separate departments
- Zero Trust assumes no implicit trust
- DMZ isolates public-facing services
- Micro-segmentation at workload level
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IDS / IPS
Intrusion Detection and Prevention Systems monitor network traffic for suspicious activity and can block it.
- IDS — detects and alerts
- IPS — detects and blocks
- Signature-based vs. anomaly-based
- Often paired with SIEM platforms
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Endpoint Protection
Secures individual devices — laptops, phones, servers — with antivirus, EDR, and device management.
- Modern EDR replaces legacy antivirus
- Behavioral detection catches zero-days
- MDM enforces policies on mobile devices
- Disk encryption protects lost devices