Chapter 9. Configuring Firewall/NAT Settings
Internet Security Router User
’s Manual
48
9.2.3
NAPT (Network Address and Port Translation) or PAT (Port Address
Translation)
Also called IP Masquerading, this feature maps many internal hosts to one globally valid Internet address. The
mapping contains a pool of network ports to be used for translation. Every packet is translated with the globally
valid Internet address and the port number is translated with an un-used port from the pool of network ports.
Figure 9.4 shows that all the hosts on the local network gain access to the Internet by mapping to only one
globally valid IP address and different port numbers from a free pool of network ports.
Figure 9.4 NAPT
– Map Any Internal PCs to a Single Global IP Address
Figure 9.5 Reverse Static NAT
– Map a Global
IP Address to An Internal PC
Figure 9.6 Reverse NAPT
– Relayed Incoming
Packets to the Internal Host Base on the
Protocol, Port Number or IP Address