P-662H/HW-D Series User’s Guide
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Chapter 16 VPN Screens
16.12.2 Diffie-Hellman (DH) Key Groups
Diffie-Hellman (DH) is a public-key cryptography protocol that allows two parties to establish
a shared secret over an unsecured communications channel. Diffie-Hellman is used within
IKE SA setup to establish session keys. 768-bit (Group 1 -
DH1
) and 1024-bit (Group 2 –
DH2
) Diffie-Hellman groups are supported. Upon completion of the Diffie-Hellman
exchange, the two peers have a shared secret, but the IKE SA is not authenticated. For
authentication, use pre-shared keys.
16.12.3 Perfect Forward Secrecy (PFS)
Enabling PFS means that the key is transient. The key is thrown away and replaced by a brand
new key using a new Diffie-Hellman exchange for each new IPSec SA setup. With PFS
enabled, if one key is compromised, previous and subsequent keys are not compromised,
because subsequent keys are not derived from previous keys. The (time-consuming) Diffie-
Hellman exchange is the trade-off for this extra security.
This may be unnecessary for data that does not require such security, so PFS is disabled
(
None
) by default in the ZyXEL Device. Disabling PFS means new authentication and
encryption keys are derived from the same root secret (which may have security implications
in the long run) but allows faster SA setup (by bypassing the Diffie-Hellman key exchange).
16.13 Configuring Advanced IKE Settings
Click
Advanced
in the
screen to open this screen.
Summary of Contents for 802.11g ADSL 2+ 4-Port Security Gateway HW-D Series
Page 2: ......
Page 10: ...P 662H HW D Series User s Guide 10 Customer Support ...
Page 24: ...P 662H HW D Series User s Guide 24 Table of Contents ...
Page 32: ...P 662H HW D Series User s Guide 32 List of Figures ...
Page 38: ...P 662H HW D Series User s Guide 38 List of Tables ...
Page 64: ...P 662H HW D Series User s Guide 64 Chapter 2 Introducing the Web Configurator ...
Page 84: ...P 662H HW D Series User s Guide 84 Chapter 4 Bandwidth Management Wizard ...
Page 108: ...P 662H HW D Series User s Guide 108 Chapter 5 WAN Setup ...
Page 122: ...P 662H HW D Series User s Guide 122 Chapter 6 LAN Setup ...
Page 156: ...P 662H HW D Series User s Guide 156 Chapter 8 DMZ ...
Page 202: ...P 662H HW D Series User s Guide 202 Chapter 11 Firewall Configuration ...
Page 210: ...P 662H HW D Series User s Guide 210 Chapter 12 Anti Virus Packet Scan ...
Page 214: ...P 662H HW D Series User s Guide 214 Chapter 13 Content Filtering ...
Page 232: ...P 662H HW D Series User s Guide 232 Chapter 14 Content Access Control ...
Page 238: ...P 662H HW D Series User s Guide 238 Chapter 15 Introduction to IPSec ...
Page 273: ...P 662H HW D Series User s Guide Chapter 17 Certificates 273 Figure 144 My Certificate Details ...
Page 292: ...P 662H HW D Series User s Guide 292 Chapter 18 Static Route ...
Page 304: ...P 662H HW D Series User s Guide 304 Chapter 19 Bandwidth Management ...
Page 308: ...P 662H HW D Series User s Guide 308 Chapter 20 Dynamic DNS Setup ...
Page 332: ...P 662H HW D Series User s Guide 332 Chapter 22 Universal Plug and Play UPnP ...
Page 338: ...P 662H HW D Series User s Guide 338 Chapter 23 System ...
Page 344: ...P 662H HW D Series User s Guide 344 Chapter 24 Logs ...
Page 350: ...P 662H HW D Series User s Guide 350 Chapter 25 Tools ...
Page 364: ...P 662H HW D Series User s Guide 364 Chapter 27 Troubleshooting ...
Page 368: ...P 662H HW D Series User s Guide 368 Product Specifications ...
Page 372: ...P 662H HW D Series User s Guide 372 Appendix C Wall mounting Instructions ...
Page 408: ...P 662H HW D Series User s Guide 408 Appendix F Wireless LANs ...
Page 420: ...P 662H HW D Series User s Guide 420 Appendix H Command Interpreter ...
Page 436: ...P 662H HW D Series User s Guide 436 Appendix L NetBIOS Filter Commands ...
Page 462: ...P 662H HW D Series User s Guide 462 Appendix M Internal SPTGEN ...
Page 484: ...P 662H HW D Series User s Guide 484 Appendix P Triangle Route ...