Lucent Technologies PortMaster - Manual (Page 147)

Configuring Filters 9-5
Creating Filters
Creating Filters
You construct a filter by creating the filter and then adding rules that permit or deny
certain types of packets. A maximum of 256 filter rules per filter is allowed for the
PortMaster 3 and IRX. For other PortMaster products, the maximum number of filter
rules allowed is 100. The PortMaster generates an error message when the number of
filter rules exceeds the limit.
Packets are evaluated in the same order as the rules are listed. Therefore, the rules
representing the highest security concern should be specified early in the list of rules,
followed by a rule limiting the volume of traffic.
User filters are attached to users configured for dial-in SLIP or PPP access. When a user
makes a PPP or SLIP connection, the designated filters are attached to the network
interface created for that connection.
Location filters are attached to dial-out locations using SLIP or PPP connections. When
the connection is established to a remote site, the designated filters are attached to the
network interface used.
You can attach filters for incoming packets, or for outgoing packets or for both. It is
usually more effective to filter incoming packets so that you can protect the PortMaster
itself.
For more detailed instructions on using the filter commands, see the PortMaster Command
Line Reference.
To create a filter, use the following command:
Command> add filter Filtername
You must then use the appropriate set command to add rules that permit or deny
packets. A maximum of 256 filter rules per filter is allowed. The PortMaster generates
an error message when the number of filter rules exceeds the limit.
See the following sections for instructions:
• “Creating IP Filters” on page 9-6
• “Filtering TCP and UDP Packets” on page 9-7
• “Creating IPX Filters” on page 9-7