
Examples and Implementation Notes
117348-A Rev. A B-5
Table B-1 lists sample predefined criteria, ranges, and actions for some common
filtering goals.
Table B-1. Predefined Criteria, Ranges, and Actions for Sample Inbound Traffic Filters
Filtering Goal Criteria Path Ranges Action Path Notes
Configure a
subset of
allowed Telnet,
TFTP, and FTP
users
Criteria > Add > IP
Source Address
Client IP source
addresses
Use
dotted-decimal
format.
Action > Add >
Accept
This strategy works only if the
destination IP address is one
of the router’s interfaces and if
the protocol or well-known
port is Telnet, TFTP, or FTP.
Configure a
router to drop
BootP requests
from particular
clients
Criteria > Add >
UDP Frame > UDP
Destination Port
MAC addresses of
the BootP clients
Action > Add >
Drop
Drop inbound
Telnet traffic
Criteria > Add > IP >
TCP Frame > TCP
Destination Port
23
See T
able 5-6 in
Chapter
5 for a list
of common TCP
port ranges.
Action > Add >
Drop
For a more secure method,
create a user-defined filter
(see T
able B-2).
This filter will not stop remote
users from establishing a
Telnet session with the router.
To do that, you must also
create outbound traffic filters
on the remote circuits.
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