SMC Networks SMC7816M, SMC7816VSW P, F, 7-17

C ONFIGURING P ACKET F ILTERING
7-17
•NetBIOS – Blocks NetBIOS packets. (Default: Disabled)
- NetBIOS is commonly used in local area networks to facilitate sharing
resources such as printers or files between computers. However,
when providing network services over the Internet to different
customers, all information about local resources should be protected.
Sending NetBIOS packets over TCP or UDP protocols can be
manually disabled at the host computer. However, to ensure that this
information is never sent out on the Internet, NetBIOS packet
filtering should be enabled on all data ports if the switch is not
operating behind a firewall.
- When NetBIOS packet filtering is enabled, NetBIOS packets
addressed to any
of the TCP or UDP ports 136-139 or 445, and
carrying a DSAP
7
value of 0xE0 or 0xF0, will be dropped from the
specified interface.
- To specify a port list, use a hyphen to indicate a range of p orts, or a
comma to indicate a group of non-consecutive ports.
- This switch provides a total of 7 masks for filtering functions,
including IP-MAC address packet filtering, NetBIOS packet filtering,
DHCP packet filtering, and ACLs. Three masks are allocated to
NetBIOS packet filtering if enabled on any interface. These masks will
be released for use by other filtering functions if NetBIOS packet
filtering is disabled on all interfaces.
7. DSAP - Destination Server Access Point; i.e., a session service tag