Patton electronic SmartNode 4110 Series manual Static Napt, Dynamic NAT

SmartWare Software Configuration Guide 11 • NAT/NAPT configuration

Global Network

WAN

131.1.1.10 - 131.1.1.15

(Local Interface Address) 192.168.1.1

131.1.1.1 (Global Interface Address)

131.1.1.10 - 131.1.1.15 (Global NAT Address Pool)

Source Address modified

Destination Address modified

Local Network

LAN

192.168.1.30 - 192.168.1.39

Figure 17. 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.

WAN

131.1.1.1:80

131.1.1.3:23

(Local Interface Address) 192.168.1.1

131.1.1.1(Global Interface Address)

131.1.1.3(Global NAPT Address)

Source Address modified

Destination Address modified

LAN

192.168.1.20:80

192.168.1.20:23

Figure 18. Static NAPT

Note Be careful when mapping ports the SmartNode uses itself (e.g. Telnet,

TFTP) because the SmartNode might become inaccessible.

Dynamic NAT

NAT only modifies addresses but not ports. Dynamic NAT assigns a global address from a global NAT address pool each time a local host wants to access the global network. It creates a dynamic NAT entry for the reverse path. If a connection is idle for some time (2 minutes), the dynamic NAT entry is removed. Should Dynamic NAT run out of global addresses, it lets Dynamic NAPT handle the connection (which may lead to an unex- pected behavior).

Introduction 134