ATU-R130 ADSL Ethernet Router User’s Guide

28

4.

If the interface named eth-0 is not already displaying, select it from the drop-

down list and click

.

The eth-0 interface specifies that your default Ethernet (LAN) interface

{

XE "LAN

interface"

}

is running DHCP relay for your LAN. Typically, this is the only interface you

need to specify here. If the ATU-R130 has additional interfaces that you want to

perform DHCP relay, you can select and add them.

(You can also delete an interface from the table by clicking

in the right column.)

5.

Click

.

A page displays to confirm your changes, and then the program returns to the DHCP

Relay Configuration page.

6.

Follow the instructions in “Setting the DHCP Mode”on page 28 to set the DHCP

mode to DHCP Relay.

Setting the DHCP Mode{ XE "DHCP:setting operating mode" }

You should set the DHCP mode only after you have configured DHCP relay or DHCP

server settings. See “Configuring DHCP Server”on page 23 or “Configuring DHCP Relay”

on page 27 for additional instructions.

Follow these instructions to set the DHCP mode:

1.

Click the LAN tab, and then click

DHCP Mode

in the task bar.

2.

From the DHCP Mode drop-down list, choose

DHCP Server

,

DHCP Relay

, or

none

.

If you choose none, your LAN computers must be configured with static IP

addresses.

3.

Click

.

4.

Click the Admin tab, and then click

Commit & Reboot

in the task bar.

5.

Click

to save your changes to permanent memory.

ATU-R130 ADSL Ethernet Router User’s Guide

29

7

Configuring Network Address Translation

This chapter provides Network Address Translation (NAT) instructions for modifying the

default configuration on your device.

Your Default NAT Setup

By default, NAT is enabled, with a napt rule configured to perform the following translation:

{

XE

"NAT:default configuration"

}

These private IP addresses:

...are translated to:

192.168.1.2

192.168.1.3

.

.

.

192.168.1.13

Your ISP-assigned

public IP address

For a description of napt rules, see page 33. This default NAT setup assumes that, on each

LAN computer, you configured TCP/IP properties as follows:

?

You selected the check box that enables them to receive their IP addresses

automatically (that is, to use a DHCP server);

or,

?

You assigned static IP addresses to your PCs in the range 192.168.1.2 through

192.168.1.13.

If your computers are not configured in one of these ways

, you can either change the IP

addresses on your computers to match the NAT setup or delete this NAT rule and add a new

one that matches the addresses you assigned to your computers (see “Adding NAT Rules”

on

page 33 for instructions).

Viewing NAT Global Settings

and Statistics

{

XE "NAT:global settings"

}

To view your NAT settings, log into Configuration Manager, click the

Services tab. The NAT Configuration page displays by default, as shown in Figure .

Figure 19. NAT Configuration Page{ XE "NAT Configuration page" }{

XE "Pages:NAT Configuration" }

ATU-R130 ADSL Ethernet Router User’s Guide

30

The NAT Configuration page contains the following elements:

?

The NAT Options drop-down list, which provides access to the Global Information page

(shown by default), the NAT Rule Configuration page, and the NAT Translations page,

which shows current translations.

?

Enable/Disable radio buttons, which allow you to turn on or off the NAT feature.

?

The NAT Global Information table, which displays the following settings that apply to all

NAT rule translations:

Field

Description

TCP Idle Timeout (sec)

For a NAT translation session on data that

uses the TCP protocol, the translation will

no longer be performed if no matching data

packets are received after the specified

time has elapsed.

TCP Close Wait (sec)

For a NAT translation on data using the

TCP protocol, after a communication

session has been closed, the translation

will no longer be performed if no matching

data packets are received after the

specified time has elapsed.

TCP Def Timeout (sec)

For a NAT translation session on data that

uses the TCP protocol, the translation will

no longer be performed if no matching data

packets are received after the specified

time has elapsed.

UDP Timeout (sec)

Same as TCP Idle Timeout, but for UDP

packets.

ICMP Timeout (sec)

Same as TCP Idle Timeout, but for ICMP

packets.

GRE Timeout (sec)

Same as TCP Idle Timeout, but for GRE

packets.

Default Nat Age (sec)

For all other NAT translation sessions, the

number of seconds after which a

translation session will no longer be valid.

NAPT Port Start/End

When a napt rule is defined, the source

ports will be translated to sequential

numbers in this range.

If you change any values, click

, and then click the Admin tab and commit your

changes to permanent system memory (see page 17).

You can click

to view accumulated data on how many NAT rules have

been invoked and how much data has been translated. A page similar to the one is shown in

Figure displays.

ATU-R130 ADSL Ethernet Router User’s Guide

31

Figure 20. NAT Rule Global Statistics Page{ XE "NAT Rule Global Statistics page" }{ XE

"Pages:NAT Rule Global Statistics" }

The table provides basic information for each NAT rule you have set up. You can click

to restart the accumulation of the statistics at their initial values.

Viewing NAT Rules and Rule Statistics

To view the NAT rules currently defined on your system, select

NAT Rule Entry

in the NAT

Options drop-down list. The NAT Rule Configuration page displays, as shown in Figure .

Figure 21. NAT Rule Configuration Page{ XE "NAT Rule Configuration page" }{ XE "Pages:NAT

Rule Configuration" }

The NAT Rule Configuration table displays a row containing basic information for each rule. For

a description of these fields, refer to the instructions for adding rules (pages 33 through 39).

From the NAT Rule Configuration page, you can click

to add a new rule, or use the icons

in the right column to delete (

) or view details on (

) a rule.

{

XE "NAT:viewing performance statistics"

}

To view data on how often a specific NAT rule has

been used, click

in the Action(s) column. A page similar to the one show in Figure

displays:

ATU-R130 ADSL Ethernet Router User’s Guide

32

Figure 22. NAT Rule Statistics Page

{

XE "NAT Rule Statistics page"

}{

XE "Pages:NAT Rule

Statistics"

}

The statistics show how many times this rule has been invoked and how many currently active

sessions are using this rule. You can click

to reset the statistics to zeros and

to display newly accumulated data.

Viewing Current NAT Translations

To view a list of NAT translations that have recently been performed and which remain in effect

(for any of the defined rules), select

NAT Translations

from the NAT Options drop-down list.

The NAT Translations page displays, as shown in Figure :

Figure 23. NAT Translations Page{ XE "NAT Translations page" }{ XE "Pages:NAT Translations" }

For each current NAT translation session, the table contains the following fields:

Field

Description

Trans Index

The sequential number assigned to the IP

session used by this NAT translation session.

Rule ID

The ID of the NAT rule invoked.

Interface

The device interface on which the NAT rule was

invoked (from the rule definition).

Protocol

The IP protocol used by the data packets that

are undergoing translations (from the rule

definition) Example: TCP, UDP, ICMP.

Alg Type

The

Application Level Gateway

(ALG), if any,

that was used to enable this NAT translation

(ALGs are special settings that certain

applications require in order to work while NAT is

enabled).

NAT Direction

The direction (incoming or outgoing) of the

translation (from the port definition).

Entry Age

The elapsed time, in seconds, of the NAT

translation session.