ZyXEL Communications Prestige 128IMH, Руководство пользователя, Страница: 46 / 142

ZyXEL Prestige 128IMH User’s Guide
Page 5-4
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If you do not set a server IP address, SUA offers the additional benefit of firewall protection.
This is because if no server is defined, all incoming inquiries will be filtered out by the
Prestige even if you do have a server on your network. This can prevent intruders from
probing your system.
The Prestige accomplishes this address sharing by translating the internal LAN IP addresses
to a single external address that is globally unique on the Internet. For more information on
IP address translation, refer to RFC 1631, ‘The IP Network Address Translator (NAT).’
In summary:
1. SUA is an ideal, cost-effective solution for small offices with less than 20 hosts on a
LAN to concurrently access the Internet or other remote TCP/IP network.
2. SUA can provide one server address to be accessed by remote users.
3. SUA can provide firewall protection if you do not configure a server IP address. All
incoming inquiries are filtered out by the Prestige. Therefore, machines on your
network are protected.
4. UDP and TCP datagrams can be routed. In addition, ICMP echo can also be routed.
The figure below shows an example of a small office connected to the Internet via a Single
User Account using the Prestige. Note that if you enable the Single User Account feature,
your local IP address MUST be selected from the list of IP addresses set aside for private
networks.
Internet
Prestige
Static or Dynamic IP Address
assigned by ISP.
LAN IP Addresses
can be user defined or
assigned by DHCP
Figure 5-1 A Single User Account Using the Prestige