Chapter 9 Network Address Translation (NAT)

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-Oneand Server. The ZyXEL Device 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 48 on page 147.

•Choose SUA Only if you have just one public WAN IP address for your ZyXEL Device.

•Choose Full Feature if you have multiple public WAN IP addresses for your ZyXEL Device.

Finding Out More

See Section 9.6 on page 144 for advanced technical information on NAT.

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P-660HN-T1H User’s Guide