IKEv2 IPsec Virtual Private Networks

Graham Bartlett, CCIE No. 26709, has designed a number of large scale Virtual Private Networks within the UK and worked with customers throughout the world using IKEv2 and Next Generation Encryption. Graham’s interests include Security and Virtual Private Networks. Within this space he has discovered zero-day vulnerabilities, including the higest severity security advisory in the March 2015 Cisco IOS software and IOS XE software security advisory bundled publication. He has contributed to numerous IETF RFCs, and has intellectual property published as prior art. He is a CiscoLive speaker and has developed Cisco Security exam content (CCIE/CCNP). He is a CCP (Senior) IA Architect, CCP (Practitioner) Security & Information Risk Advisor, CCNP, CISSP, Cisco Security Ninja and holds a BSc(Hons) in Computer Systems and Networks.Amjad Inamdar CISSP 460898, is a Senior Technical Leader with Cisco IOS Security Engineering, India. He has primarily worked on design, development and deployment of Cisco IOS secure connectivity solutions including the industry leading FlexVPN, DMVPN, GETVPN and EzVPN solutions and is currently working on the Cisco next generation SD-WAN solution. He has contributed to IETF drafts, holds a Cisco patent and has prior art publications. He holds many industry certifications including CISSP, CCSK, CCNP Security, CCDP, CCNP R/S, CCNA (SP, Data Center, Wireless, Voice), Cisco Security Ninja and has presented security at conferences, internal forums and to Cisco customers and partners. He holds a degree (B.E) in Electronics and Communication Engineering.

• Foreword xxviiIntroduction xxxiiiPart I Understanding IPsec VPNsChapter 1 Introduction to IPsec VPNs 1The Need and Purpose of IPsec VPNs 2Building Blocks of IPsec 2Security Protocols 2Security Associations 3Key Management Protocol 3IPsec Security Services 3Access Control 4Anti-replay Services 4Confidentiality 4Connectionless Integrity 4Data Origin Authentication 4Traffic Flow Confidentiality 4Components of IPsec 5Security Parameter Index 5Security Policy Database 5Security Association Database 6Peer Authorization Database 6Lifetime 7Cryptography Used in IPsec VPNs 7Symmetric Cryptography 7Asymmetric Cryptography 8The Diffie-Hellman Exchange 8Public Key Infrastructure 11Public Key Cryptography 11Certificate Authorities 12Digital Certificates 12Digital Signatures Used in IKEv2 12Pre-Shared-Keys, or Shared Secret 13Encryption and Authentication 14IP Authentication Header 15Anti-Replay 16IP Encapsulating Security Payload (ESP) 17Authentication 18Encryption 18Anti-Replay 18Encapsulation Security Payload Datagram Format 18Encapsulating Security Payload Version 3 19Extended Sequence Numbers 19Traffic Flow Confidentiality 20Dummy Packets 20Modes of IPsec 20IPsec Transport Mode 20IPsec Tunnel Mode 21Summary 22References 22Part II Understanding IKEv2Chapter 2 IKEv2: The Protocol 23IKEv2 Overview 23The IKEv2 Exchange 24IKE_SA_INIT 25Diffie-Hellman Key Exchange 26Security Association Proposals 29Security Parameter Index (SPI) 34Nonce 35Cookie Notification 36Certificate Request 38HTTP_CERT_LOOKUP_SUPPORTED 39Key Material Generation 39IKE_AUTH 42Encrypted and Authenticated Payload 42Encrypted Payload Structure 43Identity 44Authentication 45Signature-Based Authentication 46(Pre) Shared-Key-Based Authentication 47EAP 48Traffic Selectors 50Initial Contact 52CREATE_CHILD_SA 53IPsec Security Association Creation 53IPsec Security Association Rekey 54IKEv2 Security Association Rekey 54IKEv2 Packet Structure Overview 55The INFORMATIONAL Exchange 56Notification 56Deleting Security Associations 57Configuration Payload Exchange 58Dead Peer Detection/Keepalive/NAT Keepalive 59IKEv2 Request – Response 61IKEv2 and Network Address Translation 61NAT Detection 64Additions to RFC 7296 65RFC 5998 An Extension for EAP-Only Authentication in IKEv2 65RFC 5685 Redirect Mechanism for the Internet Key ExchangeProtocol Version 2 (IKEv2) 65RFC 6989 Additional Diffie-Hellman Tests for the Internet KeyExchange Protocol Version 2 (IKEv2) 65RFC 6023 A Childless Initiation of the InternetKey Exchange Version 2 (IKEv2) Security Association (SA) 66Summary 66References 66Chapter 3 Comparison of IKEv1 and IKEv2 67Brief History of IKEv1 67Exchange Modes 69IKEv1 70IKEv2 71Anti-Denial of Service 72Lifetime 72Authentication 73High Availability 74Traffic Selectors 74Use of Identities 74Network Address Translation 74Configuration Payload 75Mobility & Multi-homing 75Matching on Identity 75Reliability 77Cryptographic Exchange Bloat 77Combined Mode Ciphers 77Continuous Channel Mode 77Summary 77References 78Part III IPsec VPNs on Cisco IOSChapter 4 IOS IPsec Implementation 79Modes of Encapsulation 82GRE Encapsulation 82GRE over IPsec 83IPsec Transport Mode with GRE over IPsec 83IPsec Tunnel mode with GRE over IPsec 84Traffic 85Multicast Traffic 85Non-IP Protocols 86The Demise of Crypto Maps 86Interface Types 87Virtual Interfaces: VTI and GRE/IPsec 87Traffic Selection by Routing 88Static Tunnel Interfaces 90Dynamic Tunnel Interfaces 91sVTI and dVTI 92Multipoint GRE 92Tunnel Protection and Crypto Sockets 94Implementation Modes 96Dual Stack 96Mixed Mode 96Auto Tunnel Mode 99VRF-Aware IPsec 99VRF in Brief 99VRF-Aware GRE and VRF-Aware IPsec 101VRF-Aware GRE over IPsec 102Summary 103Reference 104Part IV IKEv2 ImplementationChapter 5 IKEv2 Configuration 105IKEv2 Configuration Overview 105The Guiding Principle 106Scope of IKEv2 Configuration 106IKEv2 Configuration Constructs 106IKEv2 Proposal 107Configuring the IKEv2 Proposal 108Configuring IKEv2 Encryption 111Configuring IKEv2 Integrity 113Configuring IKEv2 Diffie-Hellman 113Configuring IKEv2 Pseudorandom Function 115Default IKEv2 Proposal 115IKEv2 Policy 117Configuring an IKEv2 Policy 118Configuring IKEv2 Proposals under IKEv2 Policy 119Configuring Match Statements under IKEv2 Policy 120Default IKEv2 Policy 121IKEv2 Policy Selection on the Initiator 122IKEv2 Policy Selection on Responder 124IKEv2 Policy Configuration Examples 125Per-peer IKEv2 Policy 125IKEv2 Policy with Multiple Proposals 126IKEv2 Keyring 128Configuring IKEv2 Keyring 129Configuring a Peer Block in Keyring 130Key Lookup on Initiator 132Key Lookup on Responder 133IKEv2 Keyring Configuration Example 134IKEv2 Keyring Key Points 136IKEv2 Profile 136IKEv2 Profile as Peer Authorization Database 137Configuring IKEv2 Profile 138Configuring Match Statements in IKEv2 Profile 139Matching any Peer Identity 142Defining the Scope of IKEv2 Profile 143Defining the Local IKE Identity 143Defining Local and Remote Authentication Methods 145IKEv2 Dead Peer Detection 149IKEv2 Initial Contact 151IKEv2 SA Lifetime 151NAT Keepalives 152IVRF (inside VRF) 152Virtual Template Interface 153Disabling IKEv2 Profile 153Displaying IKEv2 Profiles 153IKEv2 Profile Selection on Initiator and Responder 154IKEv2 Profile Key Points 154IKEv2 Global Configuration 155HTTP URL-based Certificate Lookup 156IKEv2 Cookie Challenge 156IKEv2 Call Admission Control 157IKEv2 Window Size 158Dead Peer Detection 158NAT Keepalive 159IKEv2 Diagnostics 159PKI Configuration 159Certificate Authority 160Public-Private Key Pair 162PKI Trustpoint 163PKI Example 164IPsec Configuration 166IPsec Profile 167IPsec Configuration Example 168Smart Defaults 168Summary 169Chapter 6 Advanced IKEv2 Features 171Introduction to IKEv2 Fragmentation 171IP Fragmentation Overview 172IKEv2 and Fragmentation 173IKEv2 SGT Capability Negotiation 178IKEv2 Session Authentication 181IKEv2 Session Deletion on Certificate Revocation 182IKEv2 Session Deletion on Certificate Expiry 184IKEv2 Session Lifetime 185Summary 187References 188Chapter 7 IKEv2 Deployments 189Pre-shared-key Authentication with Smart Defaults 189Elliptic Curve Digital Signature Algorithm Authentication 194RSA Authentication Using HTTP URL Lookup 200IKEv2 Cookie Challenge and Call Admission Control 207Summary 210Part V FlexVPNChapter 8 Introduction to FlexVPN 211FlexVPN Overview 211The Rationale 212FlexVPN Value Proposition 213FlexVPN Building Blocks 213IKEv2 213Cisco IOS Point-to-Point Tunnel Interfaces 214Configuring Static P2P Tunnel Interfaces 214Configuring Virtual-Template Interfaces 216Auto-Detection of Tunnel Encapsulation and Transport 219Benefits of Per-Peer P2P Tunnel Interfaces 221Cisco IOS AAA Infrastructure 221Configuring AAA for FlexVPN 222IKEv2 Name Mangler 223Configuring IKEv2 Name Mangler 224Extracting Name from FQDN Identity 225Extracting Name from Email Identity 226Extracting Name from DN Identity 226Extracting Name from EAP Identity 227IKEv2 Authorization Policy 228Default IKEv2 Authorization Policy 229FlexVPN Authorization 231Configuring FlexVPN Authorization 233FlexVPN User Authorization 235FlexVPN User Authorization, Using an External AAA Server 235FlexVPN Group Authorization 237FlexVPN Group Authorization, Using a Local AAA Database 238FlexVPN Group Authorization, Using an External AAA Server 239FlexVPN Implicit Authorization 242FlexVPN Implicit Authorization Example 243FlexVPN Authorization Types: Co-existence and Precedence 245User Authorization Taking Higher Precedence 247Group Authorization Taking Higher Precedence 249FlexVPN Configuration Exchange 250Enabling Configuration Exchange 250FlexVPN Usage of Configuration Payloads 251Configuration Attributes and Authorization 253Configuration Exchange Examples 259FlexVPN Routing 264Learning Remote Subnets Locally 265Learning Remote Subnets from Peer 266Summary 268Chapter 9 FlexVPN Server 269Sequence of Events 270EAP Authentication 271EAP Methods 272EAP Message Flow 273EAP Identity 273EAP Timeout 275EAP Authentication Steps 275Configuring EAP 277EAP Configuration Example 278AAA-based Pre-shared Keys 283Configuring AAA-based Pre-Shared Keys 284RADIUS Attributes for AAA-Based Pre-Shared Keys 285AAA-Based Pre-Shared Keys Example 285Accounting 287Per-Session Interface 290Deriving Virtual-Access Configuration from a Virtual Template 291Deriving Virtual-Access Configuration from AAA Authorization 293The interface-config AAA Attribute 293Deriving Virtual-Access Configuration from an Incoming Session 294Virtual-Access Cloning Example 295Auto Detection of Tunnel Transport and Encapsulation 297RADIUS Packet of Disconnect 299Configuring RADIUS Packet of Disconnect 300RADIUS Packet of Disconnect Example 301RADIUS Change of Authorization (CoA) 303Configuring RADIUS CoA 304RADIUS CoA Examples 305Updating Session QoS Policy, Using CoA 305Updating the Session ACL, Using CoA 307IKEv2 Auto-Reconnect 309Auto-Reconnect Configuration Attributes 310Smart DPD 311Configuring IKEv2 Auto-Reconnect 313User Authentication, Using AnyConnect-EAP 315AnyConnect-EAP 315AnyConnect-EAP XML Messages for User Authentication 316Configuring User Authentication, Using AnyConnect-EAP 318AnyConnect Configuration for Aggregate Authentication 320Dual-factor Authentication, Using AnyConnect-EAP 320AnyConnect-EAP XML Messages for dual-factor authentication 322Configuring Dual-factor Authentication, Using AnyConnect-EAP 324RADIUS Attributes Supported by the FlexVPN Server 325Remote Access Clients Supported by FlexVPN Server 329FlexVPN Remote Access Client 329Microsoft Windows7 IKEv2 Client 329Cisco IKEv2 AnyConnect Client 330Summary 330Reference 330Chapter 10 FlexVPN Client 331Introduction 331FlexVPN Client Overview 332FlexVPN Client Building Blocks 333IKEv2 Configuration Exchange 334Static Point-to-Point Tunnel Interface 334FlexVPN Client Profile 334Object Tracking 334NAT 335FlexVPN Client Features 335Dual Stack Support 335EAP Authentication 335Dynamic Routing 335Support for EzVPN Client and Network Extension Modes 336