Zyxel P-870HN-51b Router Manual PDF (Setup & Configuration Guide)

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Chapter 8 Network Address Translation (NAT)

P-870HN-51b User’s Guide

146

8.3.1

The Port Forwarding Edit Screen

This screen lets you create or edit a port forwarding rule. Select

User Define

in

the

Service Name

field or click the rule’s

Edit

icon in the

Port Forwarding

screen to open the following screen.

Figure 71

Port Forwarding Edit

Internal Start

Port

This is the first internal port number that identifies a service.

Internal End

Port

This is the last internal port number that identifies a service.

Server IP

Address

This field displays the inside IP address of the server.

Modify

Click the

Edit

icon to go to the screen where you can edit the port

forwarding rule.

Click the

Remove

icon to delete an existing port forwarding rule. Note

that subsequent rules move up by one when you take this action.

Apply

Click

Apply

to save your changes back to the Device.

Cancel

Click

Cancel

to return to the previous configuration.

Table 39

NAT Port Forwarding (continued)

LABEL

DESCRIPTION

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The following table describes the labels in this screen.

8.4

The Trigger Port Screen

Some services use a dedicated range of ports on the client side and a dedicated

range of ports on the server side. With regular port forwarding you set a

forwarding port in NAT to forward a service (coming in from the server on the

WAN) to the IP address of a computer on the client side (LAN). The problem is

that port forwarding only forwards a service to a single LAN IP address. In order to

use the same service on a different LAN computer, you have to manually replace

the LAN computer's IP address in the forwarding port with another LAN

computer's IP address.

Table 40

Port Forwarding Edit

LABEL

DESCRIPTION

Active

Clear the check box to disable the rule. Select the check box to enable it.

This field is not editable if you are configuring a

User Define

rule.

Service Name

Enter a name to identify this rule. This field is read-only if you click the

Edit

icon in the

Port Forwarding

screen.

WAN Interface

Select a WAN interface for which you want to configure port forwarding

rules.

External Start

Port

Enter the original destination port for the packets.

To forward only one port, enter the port number again in the

External

End Port

field.

To forward a series of ports, enter the start port number here and the

end port number in the

External End Port

field.

External End

Port

Enter the last port of the original destination port range.

To forward only one port, enter the port number in the

External Start

Port

field above and then enter it again in this field.

To forward a series of ports, enter the last port number in a series that

begins with the port number in the

External Start Port

field above.

Internal Start

Port

Enter the port number here to which you want the Device to translate

the incoming port. For a range of ports, enter the first number of the

range to which you want the incoming ports translated.

Internal End

Port

Enter the last port of the translated port range.

Server IP

Address

Enter the inside IP address of the virtual server here.

Protocol

Select the protocol supported by this virtual server. Choices are

TCP

,

UDP

, or

TCP/UDP

.

Back

Click

Back

to return to the previous screen.

Apply

Click

Apply

to save your changes back to the Device.

Cancel

Click

Cancel

to begin configuring this screen afresh.

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Chapter 8 Network Address Translation (NAT)

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Trigger port forwarding solves this problem by allowing computers on the LAN to

dynamically take turns using the service. The Device records the IP address of a

LAN computer that sends traffic to the WAN to request a service with a specific

port number and protocol (a "trigger" port). When the Device's WAN port receives

a response with a specific port number and protocol ("open" port), the Device

forwards the traffic to the LAN IP address of the computer that sent the request.

After that computer’s connection for that service closes, another computer on the

LAN can use the service in the same manner. This way you do not need to

configure a new IP address each time you want a different LAN computer to use

the application.

For example:

Figure 72

Trigger Port Forwarding Process: Example

1

Jane requests a file from the Real Audio server (port 7070).

2

Port 7070 is a “trigger” port and causes the Device to record Jane’s computer IP

address. The Device associates Jane's computer IP address with the "open" port

range of 6970-7170.

3

The Real Audio server responds using a port number ranging between 6970-7170.

4

The Device forwards the traffic to Jane’s computer IP address.

5

Only Jane can connect to the Real Audio server until the connection is closed or

times out. The Device times out in three minutes with UDP (User Datagram

Protocol) or two hours with TCP/IP (Transfer Control Protocol/Internet Protocol).

Jane’s

Computer

Internet

Real Audio Server

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Click

NAT

>

Trigger Port

to open the following screen. Use this screen to view

and configure your Device’s trigger port settings.

Figure 73

Trigger Port

The following table describes the labels in this screen.

Table 41

NAT Trigger Port

LABEL

DESCRIPTION

Service Name

Select a pre-defined service from the drop-down list box. The pre-

defined service port number(s) and protocol will display in the

Trigger

port

,

Open port

and

Protocol

fields.

Otherwise, select

User Define

to open the

Rule Setup

screen where

you can manually enter the port number(s) and select the IP protocol.

WAN Interface

Select the WAN interface through which the service is forwarded.

Trigger Port

The trigger port is a port (or a range of ports) that causes (or triggers)

the Device to record the IP address of the LAN computer that sent the

traffic to a server on the WAN.

Start

This is the first port number that identifies a service.

End

This is the last port number that identifies a service.

Protocol

This is the IP protocol.

Open Port

The open port is a port (or a range of ports) that a server on the WAN

uses when it sends out a particular service. The Device forwards the

traffic with this port (or range of ports) to the client computer on the

LAN that requested the service.

Start

This is the first port number that identifies a service.

End

This is the last port number that identifies a service.

Protocol

This is the IP protocol.

Add

Click this button to add a rule to the table below.

No.

This is the rule index number (read-only).

Active

This field indicates whether the rule is active or not.

Clear the check box to disable the rule. Select the check box to enable it.

Server Name

This field displays the name of the service used by the packets for this

virtual server.

WAN Interface

This field displays the WAN interface through which the service is

forwarded.

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8.4.1

Trigger Port Configuration

This screen lets you create new port triggering rules. Click the

Add

icon in the

NAT - Trigger Port

screen to open the following screen.

Figure 74

NAT > Trigger Port > Add

Trigger Start

Port

This is the first trigger port number that identifies a service.

Trigger End

Port

This is the last trigger port number that identifies a service.

Trigger Proto.

This is the trigger IP protocol.

1

means TCP,

2

means UDP and

3

means

TCP/UDP.

Open Start

Port

This is the first open port number that identifies a service.

Open End Port

This is the last open port number that identifies a service.

Open Proto.

This is the open IP protocol.

1

means TCP,

2

means UDP and

3

means

TCP/UDP.

Modify

Click the

Edit

icon to go to the screen where you can edit the rule.

Click the

Remove

icon to delete an existing rule. Note that subsequent

rules move up by one when you take this action.

Apply

Click

Apply

to save your changes back to the Device.

Cancel

Click

Cancel

to return to the previous configuration.

Table 41

NAT Trigger Port (continued)

LABEL

DESCRIPTION

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