ATU-R130 ADSL Ethernet Router User’s Guide

38

Figure 28. NAT Rule

?

Add Page (filter Flavor) { XE "NAT Rule—

Add page - filter" }{ XE "Pages:NAT

Rule Add - filter" }

Follow these instructions to add a filter rule (see steps 1-4 under "The napt rule" on page 33 for

specific instructions corresponding to steps 1 and 2 below):

1.

Display the NAT Rule – Add Page, select

FILTER

as the Rule Flavor, and enter a

Rule ID.

2.

Select the interface on which this rule will be effective.

3.

Select a protocol to which this rule applies, or choose

ALL

.

This selection specifies which type of Internet communication will be subject to this

translation rule. You can select ALL if the rule applies to all data. Or, select TCP, UDP,

ICMP, or a number from 1-255 that represents the IANA-specified protocol number.

4.

In the Local Address From and Local Address To fields, type the starting and ending

IP addresses that identify the range of private address you want to be translated. Or,

type the same address in both fields.

If you specify a range, each address will be translated in sequence to a corresponding

address in a range of global addresses (which you specify in step 5).

The address (or range of addresses) should correspond to a private addresses (or

addresses) already in use on your network. These may be assigned statically to your PCs

or assigned dynamically using DHCP.

5.

In the Global Address From and Global Address To fields, type the starting and

ending address that identify the range of public IP addresses to translate your private

addresses to. Or, type the same address in both fields (if you also specified a single

address in step 4).

6.

Specify a Destination Address or addresses, Destination Port (or ports), or both. You

can specify a single value by entering that value in both fields.

?

Specify a destination address (or range) if you want this rule to apply only to outbound

traffic to the address (or range).

If you enter only the network ID portion of the destination address, then the rule will

apply to outbound traffic to all computers on network.

?

Specify a destination ports (or range) if you want this rule to apply to any outbound

traffic to the types of servers identified by that port number.

Port number assignments are maintained in RFCs maintained by IANA. Common

port numbers include:

20, 21—

FTP (file transfer protocol) server

ATU-R130 ADSL Ethernet Router User’s Guide

39

25—

SMTP (simple mail transfer protocol) server

80—

HTTP (World Wide Web) server

?

Specify both a destination address (or range) and a destination port (or range) if you

want this translation rule to apply to accesses to the specified server type at the

specified IP address or network.

7.

Follow steps 7-12 under "The napt rule" on page 33 to submit your changes.

The bimap rule: Performing two-way translations

{

XE "BIMAP NAT flavor"

}{

XE "NAT:BIMAP flavor"

}

Unlike the other NAT flavors, the bimap

flavor performs address translations in both the outgoing and incoming directions.

Figure

shows the fields used to establish a bimap rule.

Figure 29. NAT Rule – Add Page (bimap Flavor) { XE "NAT Rule—

Add page - bimap" }{ XE

"Pages:NAT Rule Add - bimap" }

Follow these instructions to add a bimap rule (see steps 1-4 under "The napt rule" on page 33

for specific instructions corresponding to steps 1 and 2 below):

1.

Display the NAT Rule – Add Page, select

BIMAP

as the Rule Flavor, and enter a

Rule ID.

2.

Select the interface on which this rule will be effective.

3.

In the Local Address field, type the private IP address of the computer to which you

are granting external access.

4.

In the Global Address field, type the address that you want to serve as the publicly

known address for the LAN computer.

5.

Follow steps 7-12 under "The napt rule" on page 33 to submit your changes.

The pass rule: Allowing specific addresses to pass through untranslated

You can create a pass rule to allow a range of IP addresses to remain untranslated when

another rule would otherwise do so.

{

XE "PASS - NAT flavor"

}{

XE "NAT:PASS flavor"

}

ATU-R130 ADSL Ethernet Router User’s Guide

40

Figure 30. NAT Rule – Add Page (pass Flavor) { XE "NAT Rule—

Add

page - pass" }{ XE "Pages:NAT Rule Add - pass" }

The pass rule must be assigned a rule ID that is a lower number than the ID assigned to the

rule it is intended to pass. In you want a specific IP address or range of addresses to not be

subject to an existing rule, say rule ID #5, then you can create a pass rule with ID #1 through

#4.

Follow these instructions to add a pass rule (see steps 1-4 under "The napt rule" on page 33 for

detailed instructions corresponding to steps 1 and 2 below):

1.

Display the NAT Rule – Add Page, select

PASS

as the Rule Flavor, and enter a Rule

ID.

2.

Select the interface on which this rule will be effective.

3.

In the Local Address From and Local Address To fields, type the lowest and highest

IP addresses that define the range of private address you want to be passed without

translation.

If you want the pass rule to act on only one address, type that address in both fields.

4.

Follow steps 7-12 under "The napt rule" on page 33 to submit your changes.

ATU-R130 ADSL Ethernet Router User’s Guide

41

8

Configuring IP Routes

You can use Configuration Manager to define specific routes for your Internet and network data.

This chapter provides instructions for creating routes.

Most users do not need to define IP routes. On a typical small home or office LAN, the existing

routes that set up the default gateways for your LAN computers and for the ATU-R130 provide the

most appropriate path for all your Internet traffic.

?

On your LAN computers, a default gateway directs all Internet traffic to the LAN port on

the ATU-R130. Your LAN computers know their default gateway either because you

assigned it to them when you modified their TCP/IP properties, or because you

configured them to receive the information dynamically from a server whenever they

access the Internet.

?

On the ATU-R130 itself, a default gateway is defined to direct all outbound Internet traffic

to a router at your ISP. This default gateway is assigned automatically by your ISP

whenever the device negotiates an Internet connection.

You may need to define routes if your home setup includes two or more networks or subnets, if

you connect to two or more ISP services, or if you connect to a remote corporate LAN.

{

XE "IP

routes:manually configuring"

}

Viewing the IP Routing Table

All IP-enabled computers and routers maintain a table of IP addresses that are commonly

accessed by their users. For each of these

destination IP addresses

, the table lists the IP address

of the first hop the data should take. This table is known as the device’s

routing table

.

To view the ATU-R130’s routing table, click the Routing tab.

The IP Route Table displays, as

shown in Figure 32.

Figure 31. IP Route Table Page{ XE "IP Route Table page" }{ XE "Pages:IP Route Table" }

The IP Route

{

XE "IP address:in device's routing table"

}

Table displays a row for each existing

route. These include routes that were predefined on the device, routes you may have added, and

routes that the device has identified automatically through communication with other devices.

The routing table should reflect a default gateway, which directs outbound Internet traffic to your

ISP. This default gateway is shown in the row containing destination address 0.0.0.0.

The following table defines the fields in the IP Routing Table.

ATU-R130 ADSL Ethernet Router User’s Guide

42

Field

Description

Destination

Specifies the IP address of the destination computer. The destination

can specified as the IP address of a specific computer or an entire

network. It can also be specified as all zeros to indicate that this route

should be used for all destinations for which no other route is defined

(this is the route that creates the default gateway).

Netmask

{

XE

"Netmask" \t "

See

Network mask

"

}

Indicates which parts of the destination address refer to the network

and which parts refer to a computer on the network. The default

gateway uses a netmask of 0.0.0.0.

NextHop

Specifies the

next

IP address to send data to when its final destination

is that shown in the destination column.

IFName

Displays the name of the interface on the device through which data is

forwarded to the specified next hop.

Route Type

{

XE "IP

routes:type"

}

Displays whether the route is direct or indirect. In a

direct

route, the

source and destination computers are on the same network, and the

router attempts to directly deliver the data to the computer. In an

indirect

route, the source and destination computers are on different

networks, and the router forwards data to a device on another network

for further handling.

Route Origin

Displays how the route was defined.

Dynamic

indicates that the route

was created automatically or predefined by your ISP or the

manufacturer. Routes you create are labeled

Local

. Other routes can

be created automatically (using RIP, as described in Chapter 8), or

defined remotely through various network management protocols

(LCL or ICMP).

Action

Displays an icon (

) you can click on to delete a route.

Adding IP Routes

{

XE "IP routes:adding"

}

Follow these instructions to add an IP route to the routing table.

1.

From the IP Route Table page, click

.

The IP Route – Add page displays, as shown in Figure 33.

Figure 32. IP Route – Add Page{ XE "IP Route – Add page" }{ XE "Pages:IP Route - Add" }

2.

Specify the destination, network mask, and gateway or next hop for this route.

To create a route that defines the default gateway for your LAN, enter 0.0.0.0 in both the

Destination and Net Mask fields. Enter your ISP’s IP address in the Gateway/NextHop field.

Note that you cannot specify the interface name, route type or route origin. These parameters

are used only for routes that are identified automatically as the device communicates with

other routing devices. For routes you create, the routing table displays system default values

in these fields.