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For example

, if you would like to block all PCs on the private LAN from accessing HTTP

sites (or “web surfing”):

1

Set the Start Port to

80

, the End Port to

80

.

2

Set the protocol to

TCP

.

3

Check the

Enable

box to the right of the entry to store settings.

4

Click

Apply

button to activate the filter rules.

Table 11. Port Filtering Menu Option

Option

Description

Start/End Port

Enters the start and end port of the port filter range

Protocol

Filter either both TCP and UDP traffic or just UDP or just TCP.

Forwarding

The Forwarding page allows you to run a publicly accessible server from your LAN by

specifying the mapping of TCP/UDP ports to a local PC. It allows incoming requests to

specific port numbers to reach a web server, FTP server, mail server, etc.

To access the

Forwarding

page,

1

Click

Advanced

in the menu bar.

2

Then click the

Forwarding

submenu.

3

To add a new rule, click on the

Create Rule

button.

Figure 17 shows an example of the menu and Table 12 describes the items you can

select.

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Figure 17. Example of Forwarding Page

To activate the port forwarding:

1

Enter the port range of the Internet traffic that you want to forward, and the IP

address of the server to which you want to forward that traffic.

2

Select the protocol(s) to be forwarded.

3

Check the

Enable

box to the right of the entry to store settings.

4

Click the

Apply

button to activate the forwarding rules.

Table 12. Forwarding Menu Option

Option

Description

Local IP

Address

Enter the IP address to which forwarded traffic should be sent.

Start/End Port

Enter the range of port numbers (start and end port) to forward. If

only a single port is desired, enter the same port number in the

Start

and

End

locations.

Protocol

Select the protocol(s) to be forwarded.

Note:

You may need to assign static IP addresses to devices on your LAN to insure that

the port forwarding you have set up will always apply to them.

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Port Triggers

The Port Triggers page allows you to configure dynamic triggers to specific devices on

the LAN. This allows for special applications that require specific port numbers with

bi-directional traffic to function properly. Applications such as video conferencing, voice,

gaming, and some messaging program features may require these special settings.

Port Triggers are similar to Port Forwarding except that they are not static ports held

open all the time. With the port triggering function, the Cable Modem/Router detects

outgoing data on a specific IP port number and opens corresponding target ports for

incoming data. If no outgoing traffic is detected on the Trigger Range ports for 10

minutes, the Target Range ports will close.

To access the

Port Triggers

page:

1

Click

Advanced

in the menu bar.

2

Then click the

Port Triggers

submenu.

Figure 18 shows an example of the menu and Table 13 describes the items you can

select.

Figure 18. Example of port Triggers Page

To activate a port trigger

1

Enter the trigger and target ports range for the Internet traffic to forward to.

64

2

Select the forwarding protocol(s).

3

Enter a name for your port triggering rule.

4

Check the

Enable

box to the right of the entry to store settings.

5

Click the

Apply

button to activate the forwarding rules.

Table 13. Port Triggers Menu Option

Option

Description

Trigger Range

(Start / End

Port)

Enter the trigger range (starting and ending ports) of the application

for which you want to enable port triggering. The application will

send data from these ports.

Target Range

(Start / End

Port)

Enter the target range (starting and ending ports) to open for the

same application. The application will receive data on these ports.

Protocol

Select the protocol for this rule.

DMZ Host

The DMZ (De-militarized Zone) Host page allows you to configure a network device (e.g.

a PC) to be exposed or visible directly to the Internet. This may be used if an application

doesn’t work with port triggers. If you have an application that won’t run properly behind

the NAT firewall, you can configure it for unrestricted two-way Internet access by defining

it as a virtual DMZ host. Adding a client to the DMZ may expose your local network to

various security risks because the client is not protected, so use this option as a last

resort.

To access the

DMZ Host

page:

1

Click

Advanced

in the menu bar.

2

Then click the

DMZ Host

submenu.

Figure 19 shows an example of the menu.

65

Figure 19. Example of DMZ Host Page

To configure DMZ settings:

1

Enter the last byte of the LAN IP address of the PC or other device on your network

that you want to configure as a DMZ host.

2

Click

Apply

.

Note:

If a specific PC is set as a DMZ Host, remember to set this back to “0” when

finished with the needed application, since this PC will be effectively exposed to the

public Internet.

Note:

You may need to assign your DMZ host a static IP address on your LAN to

insure that it will always be at that address.

RIP Setup

The RIP Setup page allows you to configure RIP (Router Information Protocol)

parameters. RIP automatically identifies and uses the best known and quickest route to

any given destination address to help reduce network congestion and delays.

RIP is a protocol that requires negotiation from both sides of the network (e.g. both the

Cable Modem/Router and your service provider’s CMTS (Cable Modem Termination

System)). Your service provider will normally set this up based on their knowledge of