Harden perimeter routers with Cisco firewall functionality and features to ensure network security
- Detect and prevent denial of service (DoS) attacks with TCP Intercept, Context-Based Access Control (CBAC), and rate-limiting techniques
- Use Network-Based Application Recognition (NBAR) to detect and filter unwanted and malicious traffic
- Use router authentication to prevent spoofing and routing attacks
- Activate basic Cisco IOS filtering features like standard, extended, timed, lock-and-key, and reflexive ACLs to block various types of security threats and attacks, such as spoofing, DoS, Trojan horses, and worms
- Use black hole routing, policy routing, and Reverse Path Forwarding (RPF) to protect against spoofing attacks
- Apply stateful filtering of traffic with CBAC, including dynamic port mapping
- Use Authentication Proxy (AP) for user authentication
- Perform address translation with NAT, PAT, load distribution, and other methods
- Implement stateful NAT (SNAT) for redundancy
- Use Intrusion Detection System (IDS) to protect against basic types of attacks
- Obtain how-to instructions on basic logging and learn to easily interpret results
- Apply IPSec to provide secure connectivity for site-to-site and remote access connections
- Read about many, many more features of the IOS firewall for mastery of router security
The Cisco IOS firewall offers you the feature-rich functionality that you've come to expect from best-of-breed firewalls: address translation, authentication, encryption, stateful filtering, failover, URL content filtering, ACLs, NBAR, and many others. Cisco Router Firewall Security teaches you how to use the Cisco IOS firewall to enhance the security of your perimeter routers and, along the way, take advantage of the flexibility and scalability that is part of the Cisco IOS Software package.
Each chapter in Cisco Router Firewall Security addresses an important component of perimeter router security. Author Richard Deal explains the advantages and disadvantages of all key security features to help you understand when they should be used and includes examples from his personal consulting experience to illustrate critical issues and security pitfalls. A detailed case study is included at the end of the book, which illustrates best practices and specific information on how to implement Cisco router security features.
Whether you are looking to learn about firewall security or seeking how-to techniques to enhance security in your Cisco routers, Cisco Router Firewall Security is your complete reference for securing the perimeter of your network.
This book is part of the Networking Technology Series from Cisco Press¿ which offers networking professionals valuable information for constructing efficient networks, understanding new technologies, and building successful careers.
Table of Contents:
I. SECURITY OVERVIEW AND FIREWALLS.
1. Security Threats.
Planning for Security.
Causes of Security Problems.
Types of Security Threats.
External and Internal Threats.
Unstructured and Structured Threats.
Categories of Threats.
Denial of Service Attacks.
Designing a Security Solution.
The Cisco Security Wheel.
2. Introduction to Firewalls.
Definition of a Firewall.
Controlling Traffic and the OSI Reference Model.
OSI Reference Model Overview.
Firewalls and the OSI Reference Model.
Application Gateway Firewalls.
Firewalls and Other Services.
Firewall Administration and Management.
Cisco IOS Security.
Cisco IOS Uses.
Cisco IOS Security Features.
Cisco IOS Devices and Their Uses.
When to Use a Cisco IOS Firewall.
II. MANAGING ACCESS TO ROUTERS.
3. Accessing a Router.
Types of Authentication.
No Password Authentication.
Static Password Authentication.
Aging Password Authentication.
One-Time Password Authentication.
Token Card Services.
Methods of User EXEC Access.
Local Access: Console and Auxiliary.
Privileged EXEC Access.
Other Access Items.
4. Disabling Unnecessary Services.
Disabling Global Services.
Cisco Discovery Protocol.
TCP and UDP Small Servers.
IP Source Routing.
FTP and TFTP.
Disabling Interface Services.
CDP on Insecure Interfaces.
Maintenance Operation Protocol.
Manual Configuration Example of Disabling Services on a Perimeter Router.
5. Authentication, Authorization, and Accounting.
Methods of Authentication.
Methods of Authorization.
Methods of Accounting.
Preparation for SCP.
III. NONSTATEFUL FILTERING TECHNOLOGIES.
6. Access List Introduction.
Access List Overview.
ACLs and Filtering.
Types of ACLs.
Basic ACL Configuration.
Converting a Subnet Mask to a Wildcard Mask.
Wildcard Mask Mistakes.
7. Basic Access Lists.
Types of ACLs.
Fragments and Extended ACLs.
Additional ACL Features.
IP Accounting and ACLs.
Protection Against Attacks.
Bogon Blocking and Spoofing.
DoS and Distributed DoS Attacks.
Simple Reconnaissance Attacks.
Distributed DoS Attacks.
Blocking Unnecessary Services.
An Uphill Battle.
File Sharing: Peer-to-Peer Products.
IV. STATEFUL AND ADVANCED FILTERING TECHNOLOGIES.
8. Reflexive Access Lists.
Overview of Reflexive ACLs.
Extended Versus Reflexive ACLs.
Reflexive ACLs in Action.
Limitations of Reflexive ACLs.
Configuring Reflexive ACLs.
Reflexive ACL Examples.
9. Context-Based Access Control.
Cisco IOS Firewall Features.
Generating Alerts and Audits.
Operation of CBAC.
CBAC Enhancements over RACLs.
Supported Protocols for CBAC.
Throughput Improvement Feature.
Connections Per Second Improvement Feature.
CPU Utilization Improvement Feature.
Step 1: Interface Selection.
Step 2: ACL Configuration.
Step 3: Global Timeouts.
Step 4: Port Application Mapping.
Step 5: Inspection Rules.
Step 6: Inspection Activation.
Step 7: Troubleshooting CBAC.
10. Filtering Web and Application Traffic.
Java Blocking .
Java Blocking Example.
Operation of URL Filtering.
Advantages and Limitations of URL Filtering.
URL Filtering Implementation.
URL Filtering Verification.
URL Filtering Example.
Network-Based Application Recognition.
Components of QoS.
NBAR and Classification.
NBAR Restrictions and Limitations.
Basic NBAR Configuration.
V. ADDRESS TRANSLATION AND FIREWALLS.
11. Address Translation.
Address Translation Overview.
How Address Translation Works.
Terms Used in Address Translation.
Performing Address Translation.
Limitations of Address Translation.
Address Translation Configuration.
Configuration of NAT.
Configuration of PAT.
Configuration of Port Address Redirection.
Dealing with Overlapping Addresses.
Configuration of Traffic Distribution.
Configuration of Translation Limits.
Verifying and Troubleshooting Address Translation.
NAT and CBAC Example.
12. Address Translation Issues.
Embedded Addressing Information.
Problem with Embedding Addressing Information.
Supported Protocols and Applications.
Nonstandard Port Numbers.
Controlling Address Translation.
Using Route Maps: Dynamic Translations.
Using Route Maps: Static Translations.
Address Translation and Redundancy.
Static NAT Redundancy with HSRP.
Stateful Address Translation Failover.
Traffic Distribution with Server Load Balancing.
SLB Advantages and Limitations.
VI. MANAGING ACCESS THROUGH ROUTERS.
13. Lock-and-Key Access Lists.
Lock-and-Key and Normal ACLs.
When to Use Lock-and-Key.
Allowing Remote Administration Access.
Verification and Troubleshooting.
14. Authentication Proxy.
Introduction to AP.
Limitations of AP.
Configuring AAA on Your Router.
Configuring AAA on Your Server.
Preparing for HTTP or HTTPS.
Configuring AP Policies.
Protecting Against Access Attacks.
Verifying and Troubleshooting AP.
Simple AP Example.
Complex AP Example: CBAC and NAT.
15. Routing Protocol Protection.
Static and Black Hole Routing.
Interior Gateway Protocol Security.
Reverse-Path Forwarding (Unicast Traffic).
Unicast RPF Example.
VII. DETECTING AND PREVENTING ATTACKS.
16. Intrusion-Detection System.
Cisco Router IDS Solution.
Router IDS Process.
Memory and Performance Issues.
Step 1: Initialization Configuration.
Step 2: Logging and PostOffice Configuration.
Step 3: Audit Rule Configuration and Activation.
17. DoS Protection.
Detecting DoS Attacks.
Symptoms of Attacks.
Examining CPU Utilization to Detect DoS Attacks.
Using ACLs to Detect DoS Attacks.
Using NetFlow to Detect DoS Attacks.
TCP SYN Flood Attacks.
TCP Intercept Modes.
TCP Intercept Configuration and Verification.
CBAC and DoS Attacks.
Timeouts and Thresholds.
CBAC DoS Prevention Verification.
CBAC Example Configuration.
ICMP Rate Limiting.
18. Logging Events.
Log Message Format.
Basic Logging Configuration.
Other Logging Commands.
Logging and Error Counts.
Time and Date and the Cisco IOS.
Router Time Sources.
Manual Time and Date Configuration.
Network Time Protocol Overview.
Router Client Configuration for NTP.
Router Server Configuration for NTP.
Other NTP Commands.
NTP Configuration Example.
Embedded Syslog Manager.
ESM Filter Modules.
Introduction to ESM Setup and Configuration.
Additional Logging Information.
What to Look For.
VIII. VIRTUAL PRIVATE NETWORKS.
19. IPSec Site-to-Site Connections.
IKE Phase 1: Management Connection.
Defining IKE Phase 1 Policies.
IKE Phase 1 Peer Authentication.
Authentication with Preshared Keys.
Authentication with RSA Encrypted Nonces.
Authentication with Certificates.
IKE Phase 2: Data Connection.
Step 1: Building a Crypto ACL.
Step 2: Creating a Transform Set.
Step 3: Creating a Crypto Map.
Step 4: Activating a Crypto Map.
Step 5: Verifying a Crypto Map Configuration.
IPSec Connection Troubleshooting.
Using debug Commands.
20. IPSec Remote-Access Connections.
Remote Access Overview.
EasyVPN IPSec Support.
IPSec Remote-Access Connection Process.
Step 1: The EVC Initiates an IPSec Connection.
Step 2: The EVC Sends the IKE Phase 1 Policies.
Step 3: The EVS Accepts an IKE Phase 1 Policy.
Step 4: The EVS Authenticates the User.
Step 5: The EVS Performs IKE Mode Config.
Step 6: The EVS Handles Routing with RRI.
Step 7: The IPSec Devices Build the Data Connections.
IPSec Remote-Access EVS Setup.
Task 1: Authentication Policies.
Task 2: Group Policies.
Task 3: IKE Phase 1 Policies.
Task 4: Dynamic Crypto Maps.
Task 5: Static Crypto Map.
Task 6: Remote-Access Verification.
IPSec Remote Access Example.
IX. CASE STUDY.
21. Case Study.
Case Study Configuration.
Unnecessary Services and SSH.
Access Control Lists.
CBAC and Web Filtering.
Connection Attacks and CBAC.
NTP and Syslog.