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Chapter 4 - RASFinder Software
RF300E/RF310E 59
Filters
The network administrator can set up filters on the RASFinder for better control. Filtering can be used
when you want to block all packets originating from a specific destination (called source address
filtering) or all packets heading for a particular destination (called destination address filtering). Filters
can be set up to exclude packets of a particular protocol (TCP or UDP) or any particular field in a
LAN packet. The IP Filtering Setup dialog box lists the port, address, or Internet Control Message
Protocol (ICMP) filtering for the IP protocol.
Initially, the filtering list window, i.e., the window area that displays the Type, Port, Protocol, and
Protocol Port information is blank. This information is displayed in the window when the Add/Edit IP
Port or Address Filter dialog box is filled out.
Note: When filters are installed, the RASFinder needs to do extra processing (i.e., it needs to look
into each packet that has to be routed or bridged). Thus, installing too many filters may lead to
performance degradation.
Port filtering filters or forwards IP packets based on their specific purpose; i.e., whether they are
Telnet (TCP based) or TFTP (UDP based) packets. Address filtering filters or forwards packets
based on their source or destination IP address. Separate filtering support is provided for specific
kinds of received ICMP packets.
The filtering list window on the Port Filtering tab (above) displays the filter Type, the physical Port
(LAN, or one of the WAN ports), the Protocol (TCP or UDP), and the Protocol Port. On the Address
Filtering tab (not shown), the Protocol and Protocol Port columns are replaced by IP Address.
To add or edit a filter listing, the Add/Edit IP Port (Address) Filter dialog box is used. This dialog
box enables you to create an entry which is then displayed in the filtering list window. In the example
Add/Edit IP Port Filter dialog box, the protocol that is going to be filterred is TCP, the physical port on