ZyXEL Communications P-334WT Support Notes page 129

Filter Example
A filter for blocking the NetBIOS packets
Introduction
The NETBIOS protocol is used to share a Microsoft comupter of a workgroup. For the security concern,
the NetBIOS connection to a outside host is blocked by P-334WT router as factory defaults. Users can
remove the filter sets applied to menu 3.1 and menu 4.1 for activating the NetBIOS services. The details
of the filter settings are described as follows.
Configuration
The packets need to be blocked are as follows. Please configure two filter sets with 4 and 2 rules
respectively based on the following packets in SMT menu 21.
Filter Set 1:
Rule 1-Destination port number 137 with protocol number 6 (TCP)
Rule 2-Destination port number 137 with protocol number 17 (UDP)
Rule 3-Destination port number 138 with protocol number 6 (TCP)
Rule 4-Destination port number 138 with protocol number 17 (UDP)
Rule 5-Destination port number 139 with protocol number 6 (TCP)
Rule 6-Destination port number 139 with protocol number 17 (UDP)
Filter Set 2:
Rule 1-Source port number 137, Destination port number 53 with protocol number 6
(TCP)
Rule 2-Source port number 137, Destination port number 53 with protocol number 17
(UDP)
Before starting to set the filter rules, please enter a name for each filter set in the 'Comments' field first.