P-662H/HW-D Series User’s Guide
Chapter 15 Introduction to IPSec
237
NAT is incompatible with the
AH
protocol in both
Transport
and
Tunnel
mode. An IPSec
VPN using the
AH
protocol digitally signs the outbound packet, both data payload and
headers, with a hash value appended to the packet. When using
AH
protocol, packet contents
(the data payload) are not encrypted.
A NAT device in between the IPSec endpoints will rewrite either the source or destination
address with one of its own choosing. The VPN device at the receiving end will verify the
integrity of the incoming packet by computing its own hash value, and complain that the hash
value appended to the received packet doesn't match. The VPN device at the receiving end
doesn't know about the NAT in the middle, so it assumes that the data has been maliciously
altered.
IPSec using
ESP
in
Tunnel
mode encapsulates the entire original packet (including headers)
in a new IP packet. The new IP packet's source address is the outbound address of the sending
VPN gateway, and its destination address is the inbound address of the VPN device at the
receiving end. When using
ESP
protocol with authentication, the packet contents (in this case,
the entire original packet) are encrypted. The encrypted contents, but not the new headers, are
signed with a hash value appended to the packet.
Tunnel
mode
ESP
with authentication is compatible with NAT because integrity checks are
performed over the combination of the "original header plus original payload," which is
unchanged by a NAT device.
Transport
mode
ESP
with authentication is not compatible with NAT.
Table 86
VPN and NAT
SECURITY PROTOCOL
MODE
NAT
AH
Transport
N
AH
Tunnel
N
ESP
Transport
N
ESP
Tunnel
Y
Содержание 802.11g ADSL 2+ 4-Port Security Gateway HW-D Series
Страница 1: ...P 662H HW D Series 802 11g ADSL 2 4 Port Security Gateway User s Guide Version 3 40 Edition 1 7 2006 ...
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Страница 10: ...P 662H HW D Series User s Guide 10 Customer Support ...
Страница 24: ...P 662H HW D Series User s Guide 24 Table of Contents ...
Страница 32: ...P 662H HW D Series User s Guide 32 List of Figures ...
Страница 38: ...P 662H HW D Series User s Guide 38 List of Tables ...
Страница 64: ...P 662H HW D Series User s Guide 64 Chapter 2 Introducing the Web Configurator ...
Страница 84: ...P 662H HW D Series User s Guide 84 Chapter 4 Bandwidth Management Wizard ...
Страница 108: ...P 662H HW D Series User s Guide 108 Chapter 5 WAN Setup ...
Страница 122: ...P 662H HW D Series User s Guide 122 Chapter 6 LAN Setup ...
Страница 155: ...P 662H HW D Series User s Guide Chapter 8 DMZ 155 Figure 81 DMZ Private and Public Address Example ...
Страница 156: ...P 662H HW D Series User s Guide 156 Chapter 8 DMZ ...
Страница 188: ...P 662H HW D Series User s Guide 188 Chapter 11 Firewall Configuration Figure 97 Firewall Edit Rule ...
Страница 202: ...P 662H HW D Series User s Guide 202 Chapter 11 Firewall Configuration ...
Страница 210: ...P 662H HW D Series User s Guide 210 Chapter 12 Anti Virus Packet Scan ...
Страница 214: ...P 662H HW D Series User s Guide 214 Chapter 13 Content Filtering ...
Страница 232: ...P 662H HW D Series User s Guide 232 Chapter 14 Content Access Control ...
Страница 238: ...P 662H HW D Series User s Guide 238 Chapter 15 Introduction to IPSec ...
Страница 273: ...P 662H HW D Series User s Guide Chapter 17 Certificates 273 Figure 144 My Certificate Details ...
Страница 284: ...P 662H HW D Series User s Guide 284 Chapter 17 Certificates Figure 152 Trusted Remote Host Details ...
Страница 292: ...P 662H HW D Series User s Guide 292 Chapter 18 Static Route ...
Страница 303: ...P 662H HW D Series User s Guide Chapter 19 Bandwidth Management 303 Figure 162 Bandwidth Management Monitor ...
Страница 304: ...P 662H HW D Series User s Guide 304 Chapter 19 Bandwidth Management ...
Страница 308: ...P 662H HW D Series User s Guide 308 Chapter 20 Dynamic DNS Setup ...
Страница 332: ...P 662H HW D Series User s Guide 332 Chapter 22 Universal Plug and Play UPnP ...
Страница 338: ...P 662H HW D Series User s Guide 338 Chapter 23 System ...
Страница 344: ...P 662H HW D Series User s Guide 344 Chapter 24 Logs ...
Страница 350: ...P 662H HW D Series User s Guide 350 Chapter 25 Tools ...
Страница 363: ...P 662H HW D Series User s Guide Chapter 27 Troubleshooting 363 Figure 213 Security Setting ActiveX Controls ...
Страница 364: ...P 662H HW D Series User s Guide 364 Chapter 27 Troubleshooting ...
Страница 368: ...P 662H HW D Series User s Guide 368 Product Specifications ...
Страница 372: ...P 662H HW D Series User s Guide 372 Appendix C Wall mounting Instructions ...
Страница 408: ...P 662H HW D Series User s Guide 408 Appendix F Wireless LANs ...
Страница 420: ...P 662H HW D Series User s Guide 420 Appendix H Command Interpreter ...
Страница 436: ...P 662H HW D Series User s Guide 436 Appendix L NetBIOS Filter Commands ...
Страница 462: ...P 662H HW D Series User s Guide 462 Appendix M Internal SPTGEN ...
Страница 484: ...P 662H HW D Series User s Guide 484 Appendix P Triangle Route ...