Part 6. IPSec VPN

Table of Contents

43. IPSec Basics
43.1. IPSec
43.2. Public-Key Cryptography
43.3. Certificates
43.4. IKE IDs
43.5. Internet Key Exchange (IKE)
43.6. Connection Establishment in IKEv1
43.6.1. Phase 1
43.6.2. Mode Config
43.6.3. Phase 2
43.6.4. After the Initial Establishment
43.7. Connection Establishment in IKEv2
43.7.1. IKE_SA
43.7.2. CHILD_SA
43.7.3. After the Initial Establishment
43.8. Algorithms
43.8.1. Perfect Forward Secrecy (PFS)
43.9. Protection Against Attacks with Quantum Computers
43.9.1. Post-Quantum Pre-Shared Key (PPK)
43.10. Comparison of IKEv1 to IKEv2
43.11. Recommendations
44. Key Management
44.1. Own Keys
44.1.1. Certificate Authorities (CAs)
44.2. Foreign Keys
44.3. IKE-IDs
45. strongSwan Versions
45.1. Configuration conflicts during migration
45.2. Differences between strongSwan versions 4 and 6
45.2.1. Support for IKEv2
45.2.2. Pre-Shared key: The remote peer's IP address as the IKE ID
45.2.3. Grouping connections to the same remote peer
45.2.4. Handling of Perfect Forward Secrecy (PFS) for Phase 2
45.2.5. mode config push vs. pull
45.2.6. Welcome message for VPN clients via mode config
45.2.7. Hex encoding for Pre-Shared Keys
45.2.8. Fragmentation of IKE packets
45.2.9. NAT Traversal is always enabled
46. Connecting Individual PCs
46.1. Method
46.2. Preparing the configuration on the Intra2net system
46.2.1. Create certificate
46.2.2. Default settings for new connections
46.3. Automatic configuration for clients on the Intra2net system
46.4. Manual configuration on the Intra2net system
46.4.1. Prerequisites
46.4.2. Default Settings
46.4.3. Authentication
46.4.4. Configuring the Tunnel
46.4.5. Rights
46.4.6. Activation
47. VPN with the NCP Secure Entry Windows Client
47.1. Import
47.2. Establish connection
47.3. Connection protocols
48. VPN with the Shrew Soft VPN Client
48.1. Import
48.2. Establishing Connection
48.3. Connection Protocols
49. VPN with the NCP Secure Entry macOS Client
50. VPN with the Apple iOS devices
51. VPN with Android
51.1. Connection on the Intra2net system
51.2. Certificates
51.3. Connection on Android
52. Connecting Complete Networks
52.1. Method
52.2. Configuration on the Intra2net System
52.2.1. Prerequisites
52.2.2. Default Settings
52.2.3. Authentication
52.2.4. Configuring the Tunnel
52.2.5. Rights
52.2.6. Activation
53. Solving IP Address Conflicts in VPNs Through NAT
53.1. The Problem
53.2. Configuration
53.3. Same IPs on LAN and Peer
53.3.1. Implementation
53.4. Multiple Peers with the Same IPs
53.4.1. Implementation
53.5. Local IPs Defined by Service Provider for Remote Maintenance
53.5.1. Implementation
54. Error Diagnosis
54.1. Reading Logs
54.2. Logging in strongSwan version 4
54.2.1. The Protocol Format of the Intra2net System
54.2.2. Error in Phase 1
54.2.3. Error in Phase 2
54.3. Logging in strongSwan version 6
54.3.1. The Protocol Format of the Intra2net System
54.3.2. Error in Phase 1
54.3.3. Error in Phase 2