Default Filters; Filter 1: Netbios_Wan; Filter 2: Netbios_Lan; Filter 3: Telnet_Ftp_Wan - NETGEAR RT311 Reference Manual

Reference Guide for the Model RT311 and RT314 Internet Access Gateway Routers

Default Filters

The Model RT311 router is preconfigured with the three filters shown in
and in this section.

Filter 1: NetBIOS_WAN

The NetBIOS_WAN filter is an IP protocol filter used to prevent the sending of Windows
NetBIOS name service packets to the ISP. The ports used by NetBIOS name service are:
• 137 (TCP and UDP) NetBIOS Name Service
• 138 (TCP and UDP) NetBIOS Datagram Service
• 139 (TCP and UDP) NetBIOS Session Service
This filter is applied in Menu 4.1 - WAN Port Filter as an Output Filter set.

Filter 2: NetBIOS_LAN

The NetBIOS_LAN filter is an IP protocol filter used to block NetBIOS name service requests
from a local PC to the DNS server of the ISP. These requests are UDP packets having a source port
of 137 (NNS) and a destination port of 53 (DNS).
This filter is applied in Menu 3.1 - LAN Port Filter as an Input Filter set.

Filter 3: TELNET_FTP_WAN

The TELNET_FTP_LAN filter is an IP protocol filter used to block Telnet or FTP requests to the
router from the Internet. The filter blocks TCP packets with a destination port of 21 (FTP) or 23
(Telnet).
This filter is applied in Menu 4.1 - WAN Port Filter as an Input Filter set. If you need Telnet or FTP
access to the router from the Internet, you must remove the filter number (3) from Menu 4.1.
Configuring Filters
Figure 7-1 on page 7-2
7-11