TRENDnet TDM-E400 - Manual (Page 145)

Chapter 14. Configuring Filters and Blocking Protocols
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Field Description
Protocol The basic IP protocol criteria that must be
met for rule to be invoked. Using the options
in the drop-down list, you can specify that
packets must contain the selected protocol
(eq), that they must not contain the specified
protocol (neq), or that the rule can be invoked
regardless of the protocol (any). TCP, UDP,
and ICMP are common IP protocols; others
can be identified by number from 0-255, as
defined by the Internet Assigned Numbers
Authority (IANA).
Apply Stateful
Inspection When this option is enabled, packets are
monitored for their state (i.e., whether a
packet is the initiating packet or a subsequent
packet in an ongoing communication, etc).
This option provides a degree of security by
blocking/dropping packets that are not
received in the anticipated state. Such
packets can signify an unwelcome attempt to
gain access to a network.
Source/Destination
Port Port number criteria for the source
computer(s) (from which the packet
originates) and destination computer(s).
Port numbers identify the type of traffic that
the computer or server can handle and are
specified by the Internet Assigned Numbers
Authority (IANA). For example, port number
80 indicates a Web server, 21 indicates an
FTP server.
You can choose a port type by name from
the drop-down lists or, if not available in the
list, specify the IANA port number in the text
boxes. Select Any other port if this criteria will
not be used.
These fields will be dimmed (unavailable for
entry) unless you have selected TCP or UDP
as the protocol.
See the description of Src IP Address for the
statement options (any, eq, gt, etc.)
TCP Flag Specifies whether the rule should apply only
to TCP packets that contain the synchronous
(SYN) flag, only to those that contain the non-
synchronous (NOT-SYN) flag, or to all TCP
packets. This field will be dimmed
(unavailable for entry) unless you selected
TCP as the protocol.
ICMP Type Specifies whether the value in the type field
in ICMP packet headers will be used as
criteria. The code value can be any decimal
value from 0-255. You can specify that the
value must equal (eq) or not equal (neq) the
specified value, or you can select any to
enable the rule to be invoked on all ICMP
packets. This field will be dimmed
(unavailable for entry) unless you specify
ICMP as the protocol.