Introduction
130
IPLink Software Configuration Guide
12 • NAT/NAPT configuration
Figure 18
illustrates the basic and enhanced behavior of the Dynamic NAPT. The big arrows indicate the
direction of the connection establishment. Although only a local host can establish a connection, traffic always
flows in both directions.
Figure 18. Dynamic NAPT
Static NAPT
Dynamic NAPT does not permit hosts on the global network to access hosts on the local network. Static
NAPT makes selected services (i.e. ports) of local hosts globally accessible. Static NAPT entries map global
addresses/ports to local addresses/ports. The global address can either be the address of the global interface or a
configured global NAPT address. Usually, the local and the global port of a static NAPT entry are the same;
however, they may be different.
Figure 19. Static NAPT
Note
Be careful when mapping ports the IPLink uses itself (e.g. Telnet, TFTP)
because the IPLink might become inaccessible.
Global Network
131.1.1.1 (Global Interface Address)
131.1.1.10 - 131.1.1.15 (Global NAT Address Pool)
192.168.1.30 - 192.168.1.39
131.1.1.10 - 131.1.1.15
WAN
Source Address modified
Destination Address modified
Local Network
LAN
(Local Interface Address) 192.168.1.1
131.1.1.1 (Global Interface Address)
131.1.1.3 (Global NAPT Address)
192.168.1.20:80
131.1.1.1:80
131.1.1.3:23
WAN
192.168.1.20:23
Source Address modified
Destination Address modified
LAN
(Local Interface Address) 192.168.1.1