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Chapter 22 VPN
VMG5313-B10A/-B30A Series User’s Guide
263
Figure 136
NAT Router Between IPSec Routers
Normally you cannot set up an IKE SA with a NAT router between the two IPSec routers because
the NAT router changes the header of the IPSec packet. NAT traversal solves the problem by adding
a UDP port 500 header to the IPSec packet. The NAT router forwards the IPSec packet with the UDP
port 500 header unchanged. In the above figure, when IPSec router
A
tries to establish an IKE SA,
IPSec router
B
checks the UDP port 500 header, and IPSec routers
A
and
B
build the IKE SA.
For NAT traversal to work, you must:
• Use ESP security protocol (in either transport or tunnel mode).
• Use IKE keying mode.
• Enable NAT traversal on both IPSec endpoints.
• Set the NAT router to forward UDP port 500 to IPSec router
A
.
Finally, NAT is compatible with ESP in tunnel mode because integrity checks are performed over the
combination of the "original header plus original payload," which is unchanged by a NAT device. The
compatibility of AH and ESP with NAT in tunnel and transport modes is summarized in the following
table.
Y* - This is supported in the VMG if you enable NAT traversal.
22.4.7 ID Type and Content
With aggressive negotiation mode (see
), the VMG identifies incoming
SAs by ID type and content since this identifying information is not encrypted. This enables the
VMG to distinguish between multiple rules for SAs that connect from remote IPSec routers that
have dynamic WAN IP addresses.
Regardless of the ID type and content configuration, the VMG does not allow you to save multiple
active rules with overlapping local and remote IP addresses.
With main mode (see
), the ID type and content are encrypted to
provide identity protection. In this case the VMG can only distinguish between up to 12 different
incoming SAs that connect from remote IPSec routers that have dynamic WAN IP addresses. The
VMG can distinguish up to 48 incoming SAs because you can select between three encryption
algorithms (DES, 3DES and AES), two authentication algorithms (MD5 and SHA1) and eight key
groups when you configure a VPN rule (see
Section Figure 129 on page 251
). The ID type and
content act as an extra level of identification for incoming SAs.
Table 104
VPN and NAT
SECURITY PROTOCOL
MODE
NAT
AH
Transport
N
AH
Tunnel
N
ESP
Transport
Y*
ESP
Tunnel
Y
A
B
Содержание VMG5313-B10A
Страница 15: ...15 PART I User s Guide ...
Страница 16: ...16 ...
Страница 32: ...Chapter 2 The Web Configurator VMG5313 B10A B30A Series User s Guide 32 ...
Страница 40: ...Chapter 4 Tutorials VMG5313 B10A B30A Series User s Guide 40 ...
Страница 71: ...71 PART II Technical Reference ...
Страница 72: ...72 ...
Страница 78: ...Chapter 5 Network Map and Status Screens VMG5313 B10A B30A Series User s Guide 78 ...
Страница 106: ...Chapter 6 Broadband VMG5313 B10A B30A Series User s Guide 106 ...
Страница 162: ...Chapter 9 Routing VMG5313 B10A B30A Series User s Guide 162 ...
Страница 180: ...Chapter 10 Quality of Service QoS VMG5313 B10A B30A Series User s Guide 180 ...
Страница 198: ...Chapter 11 Network Address Translation NAT VMG5313 B10A B30A Series User s Guide 198 ...
Страница 210: ...Chapter 14 Interface Group VMG5313 B10A B30A Series User s Guide 210 ...
Страница 218: ...Chapter 15 USB Service VMG5313 B10A B30A Series User s Guide 218 ...
Страница 232: ...Chapter 17 Firewall VMG5313 B10A B30A Series User s Guide 232 ...
Страница 240: ...Chapter 19 Parental Control VMG5313 B10A B30A Series User s Guide 240 ...
Страница 250: ...Chapter 21 Certificates VMG5313 B10A B30A Series User s Guide 250 ...
Страница 296: ...Chapter 23 Voice VMG5313 B10A B30A Series User s Guide 296 ...
Страница 300: ...Chapter 24 Log VMG5313 B10A B30A Series User s Guide 300 ...
Страница 308: ...Chapter 27 xDSL Statistics VMG5313 B10A B30A Series User s Guide 308 ...
Страница 318: ...Chapter 30 Remote Management VMG5313 B10A B30A Series User s Guide 318 ...
Страница 322: ...Chapter 32 TR 064 VMG5313 B10A B30A Series User s Guide 322 ...
Страница 332: ...Chapter 36 Log Setting VMG5313 B10A B30A Series User s Guide 332 ...
Страница 335: ...Chapter 37 Firmware Upgrade VMG5313 B10A B30A Series User s Guide 335 Figure 176 Error Message ...
Страница 336: ...Chapter 37 Firmware Upgrade VMG5313 B10A B30A Series User s Guide 336 ...
Страница 352: ...Chapter 40 Troubleshooting VMG5313 B10A B30A Series User s Guide 352 ...
Страница 353: ...353 PART III Appendices Appendices contain general information Some information may not apply to your device ...
Страница 354: ...354 ...
Страница 374: ...Appendix B Wireless LANs VMG5313 B10A B30A Series User s Guide 374 ...
Страница 390: ...Appendix E Legal Information VMG5313 B10A B30A Series User s Guide 390 ...