Moxa V2403-C7-W-T [27/90] Nat network address translation

V2403 Series Linux Software Managing Communications

3-12

Example 7: Log TCP packets that visit V2403-LX’s port 25.

# iptables –A INPUT –i eth0 –p tcp --dport 25 –j LOG

Example 8: Drop all packets from MAC address 01:02:03:04:05:06.

# iptables –A INPUT –i eth0 –p all –m mac --mac-source 01:02:03:04:05:06 –j DROP

ATTENTION

In Example 8, remember to issue the command

# modprobe ipt_mac first to load the module ipt_mac.

NAT (Network Address Translation)

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

used on a connecting network. One network is designated the inside network and the other is the outside

network. Typically, the V2403-LX 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.

ATTENTION

Click on the following link for more informa

tion about NAT:

http://www.netfilter.org/documentation/HOWTO//packet

-filtering-HOWTO.html

NAT Example

The IP address of all packets leaving LAN1 are changed to 192.168.3.127 (you will need to load the module

ipt_MASQUERADE):

Enabling NAT at Bootup

In most real world situations, you will want to use a simple shell script to enable NAT when the V2403-LX boots

up. The following script is an example.

#!/bin/bash

# If you put this shell script in the /home/nat.sh