Router App NAT

Description of the module

The NAT router app is an additional feature that is not included
in the standard router firmware. It allows the router to translate
addresses from one IP address space to another by modifying network
address information in the IP header of packets.

Web Interface

After installing the NAT router app, the module’s GUI can be
accessed by clicking the module name on the Router apps page of the
router’s web interface. The left part of the GUI contains a menu
with three sections: Status, Configuration, and Customization. The
main menu of the module’s GUI is shown in Figure 1.

Status

An overview of the current status can be viewed by clicking on
the Overview item in the main menu of the module’s web interface.
This page displays a list of SNAT and DNAT rules and information
about whether the corresponding service is active or not. See
Figure 2 for an example.

Configuration

SNAT

Source NAT (SNAT) is a common form of NAT that changes the
source address of packets passing through the router. This is
typically used when an internal (private) host needs to initiate a
session to an external (public) host. The private IP address of the
source host is changed to a public IP address by the device
performing NAT.

Configuration of SNAT can be done on the Global page under the
Configuration menu section. All configuration items for SNAT
configuration are described in the table below. SNAT configuration
can handle up to 32 rules. See Figure 3 for an example.

Item	Description
Enable SNAT	Enabled, SNAT functionality of the module is turned on.
Interface	Select router interface for this rule.
Protocol	Select protocol for this rule. You can choose among Source Port, Destination Port, To Source, and To Port.

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NAT
APPLICATION NOTE

NAT
Used symbols
Danger Information regarding user safety or potential damage to the router. Attention Problems that may arise in specific situations. Information or notice Useful tips or information of special interest. Example Example of function, command or script.
Advantech Czech s.r.o., Sokolska 71, 562 04 Usti nad Orlici, Czech Republic Document No. APP-0081-EN, revised on September 5, 2022. Released in the Czech Republic.
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NAT

Contents

1 Description of the module

2 Web Interface

2.1 Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.1.1 NAT rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.2 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2.1 SNAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2.2 DNAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Related Documents

List of Figures
1 Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Status Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3 SNAT Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4 DNAT Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

NAT
1. Description of the module
Router app NAT is not contained in the standard router firmware. Uploading of this router app is described in the Configuration manual (see Chapter Related Documents). NAT router app allows router to translate adresses from one IP address space into another by modifying network address information in the IP header of packets.
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NAT
2. Web Interface
Once the installation of the module is complete, the module’s GUI can be invoked by clicking the module name on the Router apps page of router’s web interface.
Left part of this GUI contains menu with Status menu section and Configuration menu section. Customization menu section contains only the Return item, which switches back from the module’s web page to the router’s web configuration pages. The main menu of module’s GUI is shown on Figure 1.
Figure 1: Menu
2.1 Status
2.1.1 NAT rules
An overview of the current status can be viewed by clicking on the Overview item in the main menu of module web interface. At the beginning of this page is a list of SNAT and DNAT rules and information about whether the corresponding service is active or not.
Figure 2: Status Overview
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NAT
2.2 Configuration
2.2.1 SNAT
Source NAT (SNAT) is the most common form of NAT. SNAT changes the source address of the packets passing through the Router. SNAT is typically used when an internal (private) host needs to initiate a session to an external (public) host; in this case, the device that is performing NAT changes the private IP address of the source host to some public IP address.
Configuration of SNAT can be done on Global page, under Configuration menu section. All configuration items for SNAT configuration page are described in the table below. SNAT configuration can handle up to 32 rules.

Figure 3: SNAT Configuration

Item Enable SNAT Interface Protocol

Description Enabled, SNAT functionality of the module is turned on. Select router interface for this rule. Select protocol for this rule. You can choose among:
· all · TCP · UDP · TCP+UDP · UDP

Source Port Destination Port To Source To Port

Enter source IP address. Enter source port. Enter destination IP address. Enter destination port. Enter To Source IP address. Enter To Source port. Table 1: SNAT Configuration Example Items Description

NAT
2.2.2 DNAT
While SNAT changes the source address of packets, destination NAT (DNAT) changes the destination address of packets passing through the Router. DNAT is typically used when an external (public) host needs to initiate a session with an internal (private) host. The source address of return packets is automatically translated back to the IP address of the source host.
Configuration of DNAT can be done on Global page, under Configuration menu section. All configuration items for DNAT configuration page are described in the table below. DNAT configuration can handle up to 32 rules.

Figure 4: DNAT Configuration

Item Enable DNAT Interface Protocol

Description Enabled, SNAT functionality of the module is turned on. Select router interface for this rule. Select protocol for this rule. You can choose among:
· all · TCP · UDP · TCP+UDP · UDP

Source Port Destination Port To Destination To Port

Enter source IP address. Enter source port. Enter destination IP address. Enter destination port. Enter To Destination IP address. Enter To Destination port. Table 2: DNAT Configuration Example Items Description

NAT
2.2.3 NAT Example
SNAT (Source Network Address Translation) changes the private IP address of the source host to public IP address. It may also change the source port in the TCP/UDP headers. SNAT is typically used by internal users to access the Internet. It is performed after the routing decision is made.
DNAT (Destination Network Address Translation) changes the destination address in IP header of a packet. It may also change the destination port in the TCP/UDP headers. DNAT is used when we need to redirect incoming packets with a destination of a public address/port to a private IP address/port inside your network. It is performed before the routing decision is made.
Figure 5: NAT Example
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3. Related Documents
You can obtain product-related documents on Engineering Portal at icr.advantech.cz address. To get your router’s Quick Start Guide, User Manual, Configuration Manual, or Firmware go to the Router Models page, find the required model, and switch to the Manuals or Firmware tab, respectively. The Router Apps installation packages and manuals are available on the Router Apps page. For the Development Documents, go to the DevZone page.
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Advantech Router App Nat User Guide

Router App NAT

Description of the module

Web Interface

Status

Configuration

SNAT

References

Documents / Resouces

Related Manuals