ZyWALL 5 User’s Guide
216
Chapter 13 Introduction to IPSec
Figure 103
Transport and Tunnel Mode IPSec Encapsulation
13.3.1 Transport Mode
Transport
mode is used to protect upper layer protocols and only affects the data in the IP
packet. In
Transport
mode, the IP packet contains the security protocol (
AH
or
ESP
) located
after the original IP header and options, but before any upper layer protocols contained in the
packet (such as TCP and UDP).
With
ESP,
protection is applied only to the upper layer protocols contained in the packet. The
IP header information and options are not used in the authentication process. Therefore, the
originating IP address cannot be verified for integrity against the data.
With the use of
AH
as the security protocol, protection is extended forward into the IP header
to verify the integrity of the entire packet by use of portions of the original IP header in the
hashing process.
13.3.2 Tunnel Mode
Tunnel
mode encapsulates the entire IP packet to transmit it securely. A
Tunnel
mode is
required for gateway services to provide access to internal systems.
Tunnel
mode is
fundamentally an IP tunnel with authentication and encryption. This is the most common
mode of operation.
Tunnel
mode is required for gateway to gateway and host to gateway
communications.
Tunnel
mode communications have two sets of IP headers:
•
Outside header
: The outside IP header contains the destination IP address of the VPN
gateway.
•
Inside header
: The inside IP header contains the destination IP address of the final
system behind the VPN gateway. The security protocol appears after the outer IP header
and before the inside IP header.
13.4 IPSec and NAT
Read this section if you are running IPSec on a host computer behind the ZyWALL.
Summary of Contents for ZyXEL ZyWALL 5
Page 1: ...ZyWALL 5 Internet Security Appliance User s Guide Version 3 64 3 2005 ...
Page 2: ......
Page 26: ...ZyWALL 5 User s Guide 24 ...
Page 44: ...ZyWALL 5 User s Guide 42 ...
Page 86: ...ZyWALL 5 User s Guide 84 Chapter 3 Wizard Setup ...
Page 96: ...ZyWALL 5 User s Guide 94 Chapter 4 LAN Screens ...
Page 102: ...ZyWALL 5 User s Guide 100 Chapter 5 Bridge Screens ...
Page 130: ...ZyWALL 5 User s Guide 128 Chapter 7 WAN Screens Figure 45 WAN PPPoE Encapsulation ...
Page 138: ...ZyWALL 5 User s Guide 136 Chapter 7 WAN Screens Figure 50 Dial Backup Setup ...
Page 144: ...ZyWALL 5 User s Guide 142 Chapter 7 WAN Screens ...
Page 152: ...ZyWALL 5 User s Guide 150 Chapter 8 DMZ Screens ...
Page 179: ...ZyWALL 5 User s Guide Chapter 10 Firewall Screens 177 Figure 73 My Service Rule Configuration ...
Page 220: ...ZyWALL 5 User s Guide 218 Chapter 13 Introduction to IPSec ...
Page 238: ...ZyWALL 5 User s Guide 236 Chapter 14 VPN Screens Figure 110 VPN Rules IKE Network Policy Edit ...
Page 261: ...ZyWALL 5 User s Guide Chapter 15 Certificates 259 Figure 122 My Certificate Details ...
Page 280: ...ZyWALL 5 User s Guide 278 Chapter 16 Authentication Server Figure 133 Local User Database ...
Page 317: ...ZyWALL 5 User s Guide Chapter 19 Bandwidth Management 315 ...
Page 318: ...ZyWALL 5 User s Guide 316 Chapter 19 Bandwidth Management ...
Page 352: ...ZyWALL 5 User s Guide 350 Chapter 21 Remote Management ...
Page 366: ...ZyWALL 5 User s Guide 364 Chapter 23 Logs Screens Figure 188 Log Settings ...
Page 389: ...ZyWALL 5 User s Guide Chapter 24 Maintenance 387 Figure 210 Restart Screen ...
Page 390: ...ZyWALL 5 User s Guide 388 Chapter 24 Maintenance ...
Page 416: ...ZyWALL 5 User s Guide 414 Chapter 27 WAN and Dial Backup Setup ...
Page 432: ...ZyWALL 5 User s Guide 430 Chapter 30 DMZ Setup ...
Page 492: ...ZyWALL 5 User s Guide 490 Chapter 37 System Information Diagnosis ...
Page 508: ...ZyWALL 5 User s Guide 506 Chapter 38 Firmware and Configuration File Maintenance ...
Page 520: ...ZyWALL 5 User s Guide 518 Chapter 40 Remote Management ...
Page 536: ...ZyWALL 5 User s Guide 534 Chapter 42 Troubleshooting Figure 343 Java Sun ...
Page 564: ...ZyWALL 5 User s Guide 562 Appendix C IP Subnetting ...
Page 570: ...ZyWALL 5 User s Guide 568 Appendix E PPTP ...
Page 571: ...ZyWALL 5 User s Guide 569 ...
Page 572: ...ZyWALL 5 User s Guide 570 ...
Page 590: ...ZyWALL 5 User s Guide 588 Appendix G Triangle Route ...
Page 620: ...ZyWALL 5 User s Guide 618 Appendix J Importing Certificates ...
Page 622: ...ZyWALL 5 User s Guide 620 Appendix K Command Interpreter ...
Page 628: ...ZyWALL 5 User s Guide 626 Appendix L Firewall Commands ...
Page 632: ...ZyWALL 5 User s Guide 630 Appendix M NetBIOS Filter Commands ...
Page 638: ...ZyWALL 5 User s Guide 636 Appendix O Brute Force Password Guessing Protection ...
Page 660: ...ZyWALL 5 User s Guide 658 Appendix Q Log Descriptions ...