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Chapter 10. PROTECTING INTRANET COMMUNICATIONS. TYPES OF FIREWALLS. Host-based firewalls: Software installed on a computer Protects one computer anywhere Network firewalls: Filters traffic entering a network Protects all computers from external threats. VIRUS PENETRATING THE PERIMETER.
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Chapter 10 PROTECTING INTRANET COMMUNICATIONS
Chapter 10: Protecting Intranet Communications TYPES OF FIREWALLS • Host-based firewalls: • Software installed on a computer • Protects one computer anywhere • Network firewalls: • Filters traffic entering a network • Protects all computers from external threats
Chapter 10: Protecting Intranet Communications VIRUS PENETRATING THE PERIMETER
Chapter 10: Protecting Intranet Communications FIREWALL CAPABILITIES • Basic packet filtering • Stateful inspection • Application layer filtering
Chapter 10: Protecting Intranet Communications SCREENED SUBNETS • Also known as a demilitarized zone (DMZ) or a perimeter network • Acts like an air lock between internal and external networks • Useful for: • Domain Name System (DNS) servers • Web servers • Mail servers
Chapter 10: Protecting Intranet Communications SCREENED SUBNET WITH THREE-LEGGED FIREWALL
Chapter 10: Protecting Intranet Communications SCREENED SUBNET WITH TWO LAYERS OF FIREWALLS
Chapter 10: Protecting Intranet Communications WHAT IPSec PROVIDES • Communications privacy • Authentication • Packet filtering
Chapter 10: Protecting Intranet Communications HOST-TO-HOST IPSec
Chapter 10: Protecting Intranet Communications HOST-TO-NETWORK IPSec
Chapter 10: Protecting Intranet Communications NETWORK-TO-NETWORK IPSec
Chapter 10: Protecting Intranet Communications COMPARING AH AND ESP • Authentication Header (AH): • Authentication, data integrity, and antireplay • Encapsulating Security Payload (ESP): • Authentication, data integrity, and antireplay • Encryption • Use ESP unless you need to analyze packet contents
Chapter 10: Protecting Intranet Communications IPSec AUTHENTICATION • Kerberos version 5 authentication protocol • Public key certificates • Pre-shared key
Chapter 10: Protecting Intranet Communications IPSec DRAWBACKS • Slower to establish a connection • Processing overhead • Encryption prevents packet analysis • Increases network utilization • Not all applications are compatible with NAT-T • Not compatible with all domain controller communications
Chapter 10: Protecting Intranet Communications WIRELESS NETWORK ADVANTAGES • Network building with lower cost: • Fewer cables to run • Fewer switches required • Increase employee productivity: • Provide network access in conference rooms
Chapter 10: Protecting Intranet Communications WIRELESS NETWORK COMPONENTS
Chapter 10: Protecting Intranet Communications WIRELESS ENCRYPTION • Static Wired Equivalent Privacy (WEP) protocol • Dynamic WEP protocol • Wi-Fi Protected Access (WPA) protocol
Chapter 10: Protecting Intranet Communications 802.1X AUTHENTICATION
Chapter 10: Protecting Intranet Communications OTHER WIRELESS SECURITY TECHNIQUES • Media Access Control (MAC) address filtering • Disabling Service Set Identifier (SSID) broadcasts • Virtual private networks (VPNs) • Detecting rogue wireless networks • Limiting wireless leakage
Chapter 10: Protecting Intranet Communications NETWORK STUMBLER SCREENSHOT
Chapter 10: Protecting Intranet Communications WIRELESS PROVISIONING SERVICES (WPS) • Simplifies connecting to wireless hotspots • Provides consistent sign-on • Enables hotspots to be authenticated • Supported by Microsoft Windows XP Professional Service Pack 2
Chapter 10: Protecting Intranet Communications WIRELESS PROVISIONING SERVICES ARCHITECTURE
Chapter 10: Protecting Intranet Communications SUMMARY • Use host and network firewalls together for defense-in-depth • Place external servers in a screened subnet • Use IPSec to provide communications encryption and authentication • Use dynamic WEP or WPA protocols for wireless encryption and authentication