ZyXEL Communications P-3202HN-Ba, User Manual

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Chapter 9 Network Address Translation (NAT)
IAD User’s Guide
102
packet is in the local network, while the global address refers to the IP address of
the host when the same packet is traveling in the WAN side.
NAT
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.
Port Forwarding
A port forwarding set is a list of inside (behind NAT on the LAN) servers, for
example, web or FTP, that you can make visible to the outside world even though
NAT makes your whole inside network appear as a single computer to the outside
world.
SUA (Single User Account) Versus NAT
SUA (Single User Account) is a ZyNOS implementation of a subset of NAT that
supports two types of mapping,
Many-to-One
and
Server
. The IAD also supports
Full Feature
NAT to map multiple global IP addresses to multiple private LAN IP
addresses of clients or servers using mapping types as outlined in Table 33 on
page 115 .
• Choose SUA Only if you have just one public WAN IP address for your IAD.
• Choose Full Feature if you have multiple public WAN IP addresses for your IAD.
9.2 The NAT General Screen
Note: You must create a firewall rule in addition to setting up SUA/NAT, to allow traffic
from the WAN to be forwarded through the IAD.