Chapter 12 Network Address Translation (NAT)
VSG1432-B101 Series User’s Guide
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Note that inside/outside refers to the location of a host, while global/local refers to
the IP address of a host used in a packet. Thus, an inside local address (ILA) is the
IP address of an inside host in a packet when the packet is still in the local
network, while an inside global address (IGA) is the IP address of the same inside
host when the packet is on the WAN side. The following table summarizes this
information.
NAT never changes the IP address (either local or global) of an outside host.
12.8.2 What NAT Does
In the simplest form, NAT changes the source IP address in a packet received from
a subscriber (the inside local address) to another (the inside global address)
before forwarding the packet to the WAN side. When the response comes back,
NAT translates the destination address (the inside global address) back to the
inside local address before forwarding it to the original inside host. Note that the
IP address (either local or global) of an outside host is never changed.
The global IP addresses for the inside hosts can be either static or dynamically
assigned by the ISP. In addition, you can designate servers, for example, a web
server and a telnet server, on your local network and make them accessible to the
outside world. If you do not define any servers (for Many-to-One and Many-to-
Many Overload mapping), NAT offers the additional benefit of firewall protection.
With no servers defined, your ZyXEL Device filters out all incoming inquiries, thus
preventing intruders from probing your network. For more information on IP
address translation, refer to
RFC 1631
,
The IP Network Address Translator (NAT)
.
Table 51
NAT Definitions
ITEM
DESCRIPTION
Inside
This refers to the host on the LAN.
Outside
This refers to the host on the WAN.
Local
This refers to the packet address (source or destination) as the packet travels
on the LAN.
Global
This refers to the packet address (source or destination) as the packet travels
on the WAN.
Содержание VSG1432-B101 - V1.10
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Страница 8: ...Safety Warnings VSG1432 B101 Series User s Guide 8 ...
Страница 10: ...Contents Overview VSG1432 B101 Series User s Guide 10 ...
Страница 20: ...Table of Contents VSG1432 B101 Series User s Guide 20 ...
Страница 21: ...21 PART I User s Guide ...
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Страница 40: ...Chapter 2 The Web Configurator VSG1432 B101 Series User s Guide 40 ...
Страница 67: ...67 PART II Technical Reference ...
Страница 68: ...68 ...
Страница 74: ...Chapter 5 Network Map and Status Screens VSG1432 B101 Series User s Guide 74 ...
Страница 146: ...Chapter 8 Home Networking VSG1432 B101 Series User s Guide 146 ...
Страница 150: ...Chapter 9 Static Routing VSG1432 B101 Series User s Guide 150 ...
Страница 174: ...Chapter 11 Policy Forwarding VSG1432 B101 Series User s Guide 174 ...
Страница 192: ...Chapter 12 Network Address Translation NAT VSG1432 B101 Series User s Guide 192 ...
Страница 198: ...Chapter 13 Dynamic DNS Setup VSG1432 B101 Series User s Guide 198 ...
Страница 224: ...Chapter 16 Firewall VSG1432 B101 Series User s Guide 224 ...
Страница 230: ...Chapter 18 Parental Control VSG1432 B101 Series User s Guide 230 ...
Страница 278: ...Chapter 25 Traffic Status VSG1432 B101 Series User s Guide 278 ...
Страница 282: ...Chapter 26 IGMP Status VSG1432 B101 Series User s Guide 282 ...
Страница 290: ...Chapter 28 Remote Management VSG1432 B101 Series User s Guide 290 ...
Страница 294: ...Chapter 29 Time Settings VSG1432 B101 Series User s Guide 294 ...
Страница 298: ...Chapter 30 Logs Setting VSG1432 B101 Series User s Guide 298 ...
Страница 314: ...Chapter 34 Troubleshooting VSG1432 B101 Series User s Guide 314 ...
Страница 344: ...Appendix A Setting up Your Computer s IP Address VSG1432 B101 Series User s Guide 344 ...
Страница 354: ...Appendix B IP Addresses and Subnetting VSG1432 B101 Series User s Guide 354 ...
Страница 364: ...Appendix C Pop up Windows JavaScripts and Java Permissions VSG1432 B101 Series User s Guide 364 ...
Страница 380: ...Appendix D Wireless LANs VSG1432 B101 Series User s Guide 380 ...
Страница 408: ...Index VSG1432 B101 Series User s Guide 408 ...