Reference Guide for the Model RT328 and Model RH348 ISDN Routers

Implementing the Filter

Now you can proceed to define a call filter to block the three NetBIOS service ports.

The Filter Set Configuration Menu is shown in Figure 8-3.

To define a call filter:

1.Go to Menu 21 - Filter Set Configuration, and choose a name and filter set.

 

Menu 21 - Filter Set Configuration

Filter

 

Filter

 

Set #

Comments

Set #

Comments

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-----------------

------

-----------------

1

netbios

7

_______________

2

_______________

8

_______________

3

_______________

9

_______________

4

_______________

10

_______________

5

_______________

11

_______________

6

_______________

12

_______________

Enter Filter Set Number to Configure= 1

Edit Comments= netbios

Press ENTER to Confirm or ESC to Cancel:

Figure 8-3. Menu 21 Filter Set Configuration

2.Next, define the filter rules.

You want your filter to ignore (drop) UDP and TCP packets originating from ports 137, 138, and 139. Because each protocol/port combination must be specified as a separate rule, there will be six rules. Each filter set contains six rules, so you will fill one entire set. Begin with rule 1, as illustrated in Figure 8-3.

Filter Configuration

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