Moxa IA3341-LX [41/72] Nat example

IA3341 Linux User’s Manual Managing Communications

4-11

NAT

NAT (Network Address Translation) protocol translates IP addresses used on one network to

different IP addresses used on another network. One network is designated the inside network and

the other is the outside network. Typically, the IA3341 connects several devices on a network and

maps local inside network addresses to one or more global outside IP addresses, and un-maps the

global IP addresses on incoming packets back into local IP addresses.

NOTE Click on the following link for more information about iptables and NAT:

http://www.netfilter.org/documentatio

n/HOWTO/NAT-HOWTO.html

NAT Example

The IP address of the LAN1 is changed to 192.168.3.127 (you will need to load the module

ipt_MASQUERADE):

IP/Netmask: 192.168.3.100/24

Gateway: 192.168.3.127

PC1 (Linux or Windows)

LAN1: 192.168.3.100/24

Embedded Computer

LAN2: 192.168.4.127

PC2 (Linux or Windows)

IP/Netmask: 192.168.4.100/24

Gateway: 192.168.4.127

NAT Area/Private IP

LAN2

LAN1

1. #echo 1 > /proc/sys/net/ipv4/ip_forward

2. #modprobe ip_tables

3. #modprobe iptable_filter

4. #modprobe ip_conntrack

5. #modprobe iptable_nat

6. #modprobe ipt_MASQUERADE

7. #iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to-source 192.168.3.127

8. #iptables –t nat –A POSTROUTING –o eth0 –s 192.168.3.0/24 –j MASQUERADE