SMC SMCD3GN2-RES Router Manual PDF (Setup & Configuration Guide)

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Configuring Your Gateway

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SMCD3GN2 Wireless Cable Modem User Manual

Table 21. Customer Defined Filter Menu Options

Option

Description

Name

Name for identifying the custom service. The name is for reference purposes only.

Type

The type of protocol you want to filter. Choices are TCP, UDP, and TCP/UDP. Default is TCP.

LAN IPs

Lets you apply the filter to any LAN IP addresses, a single LAN IP address, or a range of LAN

IP addresses.

•

If you select one LAN IP address, enter the IP address in the

Start IP

field.

•

If you select a range of LAN IP addresses, enter the starting IP address in the

Start IP

field

and the ending IP address in the

End IP

field.

Start IP

To specify:

•

A single remote IP address, enter the remote IP address.

•

A range of remote IP addresses, enter the starting IP address here and the ending IP

address range in the next field.

This field is unavailable if the Gateway is configured for any remote IP addresses.

End IP

Ending IP address in the LAN IP address range to which the filter will be applied. This field is

unavailable if the Gateway is configured for any LAN IP address or a single LAN IP address.

From Port

Starting port number on which the filter will be applied. If necessary, contact the application

vendor for this information.

To Port

Ending port number on which the filter will be applied. If necessary, contact the application

vendor for this information.

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Configuring Your Gateway

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SMCD3GN2 Wireless Cable Modem User Manual

Configuring Special Applications

Using the Special Application menu, you can configure the Gateway to detect port triggers

for detect multiple-session applications and allow them to pass the firewall. For special

applications, besides the initial communication session, there are multiple related sessions

created during the protocol communications. Normally, a normal treats the triggered

sessions as independent sessions and blocks them. However, the Gateway can co-relate

the triggered sessions with the initial session and group them together in the NAT session

table. As a result, you need only specify which protocol type and port number you want to

track, as well as some other related parameters. In this way, the Gateway can pass the

special applications according to the supplied information.

Assume, for example, that to use H.323 in a Net Meeting application, a local client starts a

session A to a remote host. The remote host uses session A to communicate with the local

host, but it also could initiate another session B back to the local host. Since there is only

session A recorded in the NAT session table when the local host starts the communication,

session B is treated as an illegal access from the outside and is blocked. Using the Special

Application menu, you can configure the Gateway to co-relate sessions A and B and

automatically open the port for the incoming session B.

To display the Special Applications menu, click

Firewall

in the menu bar and then click the

Special Application

submenu. Figure 47 shows an example of the menu.

The maximum number of allowed triggers is 20. To enable the special application function,

check the

Enable Triggering

checkbox and click

Apply

. To disable it, uncheck the

Enable

Triggering

checkbox and click

Apply

.

Note:

The

Special Application

submenu is not available in the menu bar if

Enable Firewall

Module

is disabled in the Security Settings (Firewall) menu (see page 73).

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Configuring Your Gateway

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SMCD3GN2 Wireless Cable Modem User Manual

Figure 47. Special Application Menu

To enable port triggering:

1. In the Special Application menu, check

Enable Triggering

if it is unchecked and click the

Apply

button. The Trigger Table becomes available.

2. Click the

Add

button below

Trigger Table

. The Trigger menu appears (see Figure 48).

3. Complete the fields in fields Trigger menu (see Table 22).

4. Click

Apply

. (Or click

Back

to return to the Trigger menu or

Cancel

to cancel any

selections you made.) If you clicked

Apply

, the trigger is added to the

Trigger Table

.

5. To configure additional triggers (up to 20), repeat steps 1 through 4. When you finish, click

Apply

in the Special Applications menu to save your settings.

6. To change the settings for a trigger, click the radio button to the left of the trigger you want

to change and click the

Edit

button. When the Trigger menu appears, edit the settings as

necessary (see Table 22) and click

Apply

. Click

Apply

in the Special Application menu to

save your settings.

7. To delete a trigger, click the radio button to the left of the trigger you want to delete and

click the

Delete

button. No precautionary message appears before you delete a trigger.

Click

Apply

in the Special Application menu to save your settings.

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Configuring Your Gateway

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SMCD3GN2 Wireless Cable Modem User Manual

Figure 48. Trigger Menu

Table 22. Trigger Menu Options

Option

Description

Name

Name for identifying the trigger. The name is for reference purposes only.

Type

The type of protocol you want to use with the trigger. Choices are TCP and UDP. Default is

TCP. For example, to track the H.323 protocol, the protocol type should be TCP.

Trigger Port

From and To port ranges of the special application. For example, to track the H.323 protocol,

the From and To ports should be 1720.

Target Port

From

and

To

port ranges for the target port listening for the special application.

Interval

Specify the interval between 50 and 30000 between two continuous sessions. If the interval

exceeds this time interval setting, the sessions are considered to be unrelated.

IP Replacement

Select the IP replacement according to the application. Some applications embed the source

host's IP in the datagram and normal NAT would not translate the IP address in the datagram.

To make sure the network address translation is complete, IP replacement is necessary for

these special applications, such as H.323.

Allow sessions initiated from/to the

3

rd

host

Decide whether the sessions can start from/to a third host. To prevent hacker attacks from a

third host, this feature usually is not allowed. However, for some special applications, such as

MGCP in a VOIP application, a session initiated from a third host is permitted. For example,

assume Client A is trying to make a phone call to a host B. Client A tries to communicate with

the Media Gateway Controller (MGC) first and provides host B's number to MGC. Then MGC

checks its own database to find B and communicate with B to provide B the information about

A. B uses this information to communicate directly to A. So initially, A is talking to MGC, but

the final step has B initiating a session to A. If the third-party host-initiated session is not

allowed in this example, the whole communication fails.

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Configuring Your Gateway

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SMCD3GN2 Wireless Cable Modem User Manual

Configuring URL Blocking

Using the URL Blocking menu, you can configure the Gateway to block access to certain

Web sites from local computers by entering either a full URL address or keywords of the

Web site. the Gateway examines all the HTTP packets to block the access to those

particular sites. This feature can be used to protect children from accessing inappropriate

Web sites. You can block up to 50 sites.

Using URL blocking, you can also make up to 10 computers exempt from URL blocking and

have full access to all Web sites at any time.

To display the URL Blocking menu, click

Firewall

in the menu bar and then click the

URL

Blocking

submenu. Figure 49 shows an example of the menu.

Note:

The

URL Blocking

submenu is not available in the menu bar if

Enable Firewall

Module

is disabled in the Security Settings (Firewall) menu (see page 73).

Tip:

The Gateway provides a Schedule Rules feature that lets you configure URL blocking for

certain days, if desired. For more information, see “Configuring Schedule Rules” on page 92.

Figure 49. URL Blocking Menu

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