1. VPN Basic Concepts
- VPN (Virtual Private Network) - Virtual private line
- Tunneling - Secure communication path through encapsulation
- Encrypted Communication - Data confidentiality protection
- Authentication - Verification of legitimate users/devices
- Private Addresses - Internal network usage
Sub-keywords: End-to-end encryption, Network isolation, Secure gateway
2. VPN Types
- Internet VPN - Uses public internet connections
- IP-VPN - Uses carrier's closed network
- Entry VPN - Wide area Ethernet connection
- Remote Access VPN - Individual devices to corporate network
- Site-to-Site VPN (LAN-to-LAN) - Multi-location connections
Sub-keywords: Cloud VPN, Mobile VPN, Hybrid VPN
3. Key Protocols
-
IPsec - IP layer security protocol
- Transport Mode / Tunnel Mode
- AH (Authentication Header) - Authentication & integrity
- ESP (Encapsulating Security Payload) - Encryption & authentication
- IKE (Internet Key Exchange) - Key exchange
- SA (Security Association) - Security parameters
-
SSL/TLS-VPN - Application layer
- Clientless connection
- Web browser-based access
- PPTP - Point-to-Point Tunneling Protocol (legacy)
- L2TP - Layer 2 Tunneling Protocol
- L2TP/IPsec - Combination of L2TP and IPsec
Sub-keywords: WireGuard protocol, OpenVPN, IKEv2
4. Security Elements
- Confidentiality - Encryption
- Integrity - Tamper detection
- Authentication - Prevents impersonation
- Non-repudiation - Proof of action
Sub-keywords: CIA triad, Access control, Data protection
5. Encryption Technologies
- Symmetric Encryption - AES, 3DES
- Public Key Encryption - RSA
- Hash Functions - SHA-256, MD5
- Digital Certificates - PKI infrastructure
Sub-keywords: Key length, Cipher suites, Perfect forward secrecy
6. Authentication Methods
- Pre-Shared Key (PSK) - Shared secret
- Digital Certificate Authentication
- RADIUS Authentication
- Two-Factor Authentication (2FA)
- One-Time Password (OTP)
Sub-keywords: Biometric authentication, Smart card, LDAP integration
7. Risks and Countermeasures
- Eavesdropping Prevention - Strong encryption
- Man-in-the-Middle (MITM) - Certificate verification
- Split Tunneling - Security risks
- Log Management - Access record retention
- Vulnerability Management - Software updates
Sub-keywords: DNS leaks, Kill switch, Zero-trust architecture
8. Related Technologies/Terms
- Firewall - Integration with VPN
- NAT Traversal - Communication through NAT
- Split Tunnel - Traffic distribution
- VPN Concentrator - Dedicated VPN device
- Always-On VPN - Persistent connection
Sub-keywords: SD-WAN, Load balancing, Endpoint security
9. Operations Management
- Access Log Monitoring
- Bandwidth Control
- Redundancy & Availability
- Failover Switching
- Performance Monitoring
Sub-keywords: SLA monitoring, Capacity planning, Incident response
10. Laws & Guidelines
- Unauthorized Access Prevention Act
- Personal Information Protection Act - Data handling via VPN
- ISMS - Information Security Management System
Sub-keywords: GDPR compliance, Data sovereignty, Audit requirements