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Chapter 8 Network Address Translation (NAT) Screens
NN47923-500
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.
summarizes this information.
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) 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. You can make designated servers on the LAN 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 Business Secure Router filters out all
incoming inquiries, thus preventing intruders from probing your network. For
more information about IP address translation, refer to
The IP Network Address
Translator (NAT)
(RFC 1631).
Table 23
NAT definitions
Term
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.
Note:
NAT never changes the IP address (either local or global) of an
outside host.
Summary of Contents for BSR252
Page 28: ...28 Tables NN47923 500 ...
Page 44: ...44 Chapter 1 Getting to know your Business Secure Router NN47923 500 ...
Page 52: ...52 Chapter 2 Introducing the WebGUI NN47923 500 ...
Page 70: ...70 Chapter 3 Wizard setup NN47923 500 ...
Page 96: ...96 Chapter 5 System screens NN47923 500 ...
Page 114: ...114 Chapter 7 WAN screens NN47923 500 Figure 27 WAN IP ...
Page 120: ...120 Chapter 7 WAN screens NN47923 500 Figure 31 Dial Backup Setup ...
Page 128: ...128 Chapter 7 WAN screens NN47923 500 ...
Page 152: ...152 Chapter 9 Static Route screens NN47923 500 ...
Page 194: ...194 Chapter 11 Firewall screens NN47923 500 ...
Page 210: ...210 Chapter 13 VPN NN47923 500 Figure 67 Summary IP Policies ...
Page 222: ...222 Chapter 13 VPN NN47923 500 Figure 71 VPN Branch Office rule setup ...
Page 256: ...256 Chapter 13 VPN NN47923 500 Figure 81 VPN Client Termination advanced ...
Page 260: ...260 Chapter 13 VPN NN47923 500 ...
Page 264: ...264 Chapter 14 Certificates NN47923 500 Figure 83 My Certificates ...
Page 270: ...270 Chapter 14 Certificates NN47923 500 Figure 85 My Certificate create ...
Page 274: ...274 Chapter 14 Certificates NN47923 500 Figure 86 My Certificate details ...
Page 282: ...282 Chapter 14 Certificates NN47923 500 Figure 89 Trusted CA details ...
Page 298: ...298 Chapter 14 Certificates NN47923 500 ...
Page 316: ...316 Chapter 16 IEEE 802 1x NN47923 500 ...
Page 320: ...320 Chapter 17 Authentication server NN47923 500 Figure 106 Local User database edit ...
Page 328: ...328 Chapter 17 Authentication server NN47923 500 ...
Page 376: ...376 Chapter 20 Logs Screens NN47923 500 Figure 150 Log settings ...
Page 386: ...386 Chapter 20 Logs Screens NN47923 500 ...
Page 393: ...Chapter 21 Call scheduling screens 393 Nortel Business Secure Router 252 Configuration Basics ...
Page 394: ...394 Chapter 21 Call scheduling screens NN47923 500 ...
Page 410: ...410 Chapter 22 Maintenance NN47923 500 ...