IPsec Virtual Private Network Fundamentals (Paperback)

Description

An introduction to designing and configuring Cisco IPsec VPNs

 

Understand the basics of the IPsec protocol and learn implementation best practices

Study up-to-date IPsec design, incorporating current Cisco innovations in the security and VPN marketplace

Learn how to avoid common pitfalls related to IPsec deployment

Reinforce theory with case studies, configuration examples showing how IPsec maps to real-world solutions

 

IPsec Virtual Private Network Fundamentals provides a basic working knowledge of IPsec on various Cisco routing and switching platforms. It provides the foundation necessary to understand the different components of Cisco IPsec implementation and how it can be successfully implemented in a variety of network topologies and markets (service provider, enterprise, financial, government). This book views IPsec as an emerging requirement in most major vertical markets, explaining the need for increased information authentication, confidentiality, and non-repudiation for secure transmission of confidential data. The book is written using a layered approach, starting with basic explanations of why IPsec was developed and the types of organizations relying on IPsec to secure data transmissions. It then outlines the basic IPsec/ISAKMP fundamentals that were developed to meet demand for secure data transmission. The book covers the design and implementation of IPsec VPN architectures using an array of Cisco products, starting with basic concepts and proceeding to more advanced topics including high availability solutions and public key infrastructure (PKI). Sample topology diagrams and configuration examples are provided in each chapter to reinforce the fundamentals expressed in text and to assist readers in translating concepts into practical deployment scenarios. Additionally, comprehensive case studies are incorporated throughout to map topics to real-world solutions.

Table of Contents

Contents

Introduction

Part I   Introductory Concepts and Configuration/Troubleshooting

Chapter 1        Introduction to VPN Technologies

VPN Overview of Common Terms

Characteristics of an Effective VPN

VPN Technologies

Virtual Private Dialup Networks  

Multiprotocol Label Switching VPNs  

IPsec VPNs  

Transport Layer VPNs  

Common VPN Deployments  

Site-to-Site VPNs  

Remote Access VPNs  

Business Drivers for VPNs  

Remote Access VPN Business Drivers–A Practical Example  

Site-to-Site VPN Business Drivers–A Practical Example  

IPsec VPNs and the Cisco Security Framework  

Summary  

 

Chapter 2        IPsec Fundamentals  

Overview of Cryptographic Components  

Asymmetric Encryption  

Symmetric Encryption  

Message Authentication, Message Integrity, and Sender Nonrepudiation Mechanisms  

Public Key Encryption Methods  

RSA Public-Key Technologies  

Diffie-Hellman Key Exchange  

The IP Security Protocol (IPsec)  

IPsec Modes  

IPsec Transforms  

IPsec SA  

IPsec Configuration Elements  

Manual Keying  

The Need for Security Association and Key Management  

IKE and ISAKMP  

IKE and ISAKMP Terminology and Background  

IKE SA Negotiation and Maintenance  

IPsec Diffie-Hellman Shared Secret Key Generation Using IKE  

IKE Authentication Services  

IKE Phase I Negotiation  

IKE Phase II Negotiation  

Configuring ISAKMP  

IKE with RAVPN Extensions  

Summary

 

Chapter 3        Basic IPsec VPN Topologies and Configurations  

Site-to-Site IPsec VPN Deployments  

Site-to-Site VPN Architectural Overview for a Dedicated Circuit  

Site-to-Site Architectural Overview over a Routed Domain  

Site-to-Site IPsec VPN Deployments and GRE (IPsec+GRE)  

Site-to-Site IPsec+GRE Architectural Overview  

Site-to-Site IPsec+GRE Sample Configurations  

Hub-and-Spoke IPsec VPN Deployments  

Hub-and-Spoke Architectural Overview  

Standard Hub-and-Spoke Design without High Availability  

Clustered Spoke Design to Redundant Hubs  

Redundant Clustered Spoke Design to Redundant Hubs  

Remote Access VPN Deployments  

RAVPN Architectural Overview  

RAVPN Clients  

Standalone VPN Concentrator Designs  

Clustered VPN Concentrator Designs  

Summary  

 

Chapter 4        Common IPsec VPN Issues  

IPsec Diagnostic Tools within Cisco IOS  

Common Configuration Issues with IPsec VPNs  

IKE SA Proposal Mismatches  

IKE Authentication Failures and Errors  

IPsec SA Proposal Mismatches  

Crypto-Protected Address Space Issues (Crypto ACL Errors)  

Architectural and Design Issues with IPsec VPNs  

Troubleshooting IPsec VPNs in Firewalled Environments  

NAT Issues in IPsec VPN Designs  

The Influence of IPsec on Traffic Flows Requiring QoS  

Solving Fragmentation Issues in IPsec VPNs  

The Effect of Recursive Routing on IPsec VPNs  

Summary  

 

Part II     Designing VPN Architectures  

Chapter 5        Designing for High Availability  

Network and Path Redundancy  

IPSec Tunnel Termination Redundancy  

Multiple Physical Interface HA with Highly Available Tunnel Termination Interfaces  

Tunnel Termination HA Using HSRP/VRRP Virtual Interfaces  

HA with Multiple Peer Statements  

RP-based IPSec HA  

Managing Peer and Path Availability  

Peer Availability  

Path Availability  

Managing Path Symmetry  

Load Balancing, Load Sharing, and High Availability  

Load-Sharing with Peer Statements  

Routing  

Domain Name System (DNS)  

Cisco VPN3000 Concentrator Clustering  

IPSec Session Load-Balancing Using External Load Balancers  

Summary  

 

Chapter 6        Solutions for Local Site-to-Site High Availability  

Using Multiple Crypto Interfaces for High Availability  

Impact of Routing Protocol Reconvergence on IPsec Reconvergence  

Impact of Stale SAs on IPsec Reconvergence  

Impact of IPsec and ISAKMP SA Renegotiation on IPsec Reconvergence  

Stateless IPsec VPN High-Availability Alternatives  

Solution Overview for Stateless IPsec High Availability  

Stateless High Availability Failover Process  

Stateful IPsec VPN High-Availability Alternatives  

Solution Overview for Stateful IPsec High Availability  

Stateful High Availability Failover Process  

Summary  

Stateless IPsec VPN High Availability Design Summary  

Stateful IPsec VPN High Availability Design Summary  

 

Chapter 7        Solutions for Geographic Site-to-Site High Availability  

Geographic IPsec VPN HA with Reverse Route Injection and Multiple IPsec Peers  

Solution Overview for RRI with Multiple IPsec Peers  

Geographic IPsec VPN High Availability with IPsec+GRE and Encrypted Routing

Protocols  

Solution Overview for IPsec+GRE with Encrypted Routing Protocols  

Dynamic Multipoint Virtual Private Networks  

DMVPN Solution Design Drivers  

DMVPN Component-Level Overview and System Operation  

Summary  

 

Chapter 8        Handling Vendor Interoperability with High Availability  

Vendor Interoperability Impact on Peer Availability  

The Inability to Specify Multiple Peers  

Lack of Peer Availability Mechanisms  

Vendor Interoperability Impact on Path Availability  

IPSec HA Design Considerations for Platforms with Limited Routing

Protocol Support  

IPSec HA Design Considerations for Lack of RRI Support  

IPSec HA Design Considerations for Lack of Generic Routing Encapsulation (GRE)

Support  

Vendor Interoperability Design Considerations and Options  

Phase 1 and 2 SA Lifetime Expiry  

SADB Management with Quick Mode Delete Notify Messages  

Invalid Security Parameter Index Recovery  

Vendor Interoperability with Stateful IPSec HA  

Summary  

 

Chapter 9        Solutions for Remote-Access VPN High Availability  

IPsec RAVPN Concentrator High Availability Using Virtual Interfaces for Tunnel

Termination  

IPsec RAVPN Concentrator High Availability Using VRRP  

IPsec RAVPN Concentrator HA Using HSRP  

IPsec RAVPN Concentrator HA Using the VCA Protocol  

IPsec RAVPN Geographic HA Design Options  

VPN Concentrator Session Load Balancing Using DNS  

VPN Concentrator Redundancy Using Multiple Peers  

Summary  

 

Chapter 10      Further Architectural Options for IPsec  

IPsec VPN Termination On-a-Stick  

IPsec with Router-on-a-Stick Design Overview  

Case Study: Small Branch IPsec VPN Tunnel Termination with NAT On-a-Stick  

In-Path Versus Out-of-Path Encryption with IPsec  

Out-of-Path Encryption Design Overview  

Case Study: Firewalled Site-to-Site IPsec VPN Tunnel Termination  

Separate Termination of IPsec and GRE (GRE-Offload)  

GRE-Offload Design Overview  

Case Study: Large-Scale IPsec VPN Tunnel Termination with GRE Offload  

Summary  

 

Part III     Advanced Topics  

Chapter 11      Public Key Infrastructure and IPsec VPNs  

PKI Background  

PKI Components  

Public Key Certificates  

Registration Authorities  

Certificate Revocation Lists and CRL Issuers  

Certificate Authorities  

PKI Cryptographic Endpoints  

Life of a Public Key Certificate  

RSA Signatures and X.509v3 Certificates  

Generating Asymmetric Keypairs on Cryptographic Endpoints  

Registration and Endpoint Authentication  

Receipt and Authentication of the CA’s Certificate  

Forwarding and Signing of Public Keys  

Obtaining and Using Public Key Certificates  

PKI and the IPSec Protocol Suite–Where PKI Fits into the IPSec model  

OCSP and CRL Scalability  

OCSP  

Case Studies and Sample Configurations  

Case Study 1: PKI Integration of Cryptographic Endpoints  

Case Study 2: PKI with CA and RA  

Case Study 3: PKI with Redundant CAs (CA Hierarchy)  

Summary  

 

Chapter 12      Solutions for Handling Dynamically Addressed Peers  

Dynamic Crypto Maps  

Dynamic Crypto Map Impact on VPN Behavior  

Dynamic Crypto Map Configuration and Verification  

Tunnel Endpoint Discovery  

TED Configuration and Verification  

Case Study–Using Dynamic Addressing with Low-Maintenance Small Home Office

Deployments  

Summary  

 

Appendix A Resources  

Books  

RFCs  

Web and Other Resources  

Index