Cisco 500 Series, Configuration Manual

Page: 492 / 1140

25-28
Cisco Security Appliance Command Line Configuration Guide
OL-12172-03
Chapter 25 Configuring Application Layer Protocol Inspection
FTP Inspection
Step 1
(Optional) Add one or more regular expressions for use in traffic matching commands according to the
“Creating a Regular Expression” section on page 21-6 . See the types of text you can match in the match
commands described in Step 3 .
Step 2 (Optional) Create one or more regular expression class maps to group regular expressions according to
the
“Creating a Regular Expression Class Map” section on page 21-9 .
Step 3
(Optional) Create an FTP inspection class map by performing the following steps.
A class map groups multiple traffic matches. Traffic must match all of the match commands to match
the class map. You can alternatively identify match commands directly in the policy map. The difference
between creating a class map and defining the traffic match directly in the inspection policy map is that
the class map lets you create more complex match criteria, and you can reuse class maps.
To specify traffic that should not match the class map, use the match not command. For example, if the
match not command specifies the string “example.com,” then any traffic that includes “example.com”
does not match the class map.
For the traffic that you identify in this class map, you can specify actions such as drop, drop-connection,
reset, mask, set the rate limit, and/or log the connection in the inspection policy map.
If you want to perform different actions for each match command, you should identify the traffic directly
in the policy map.
a. Create the class map by entering the following command:
hostname(config)# class-map type inspect ftp [ match-all | match-any ] class_map_name
hostname(config-cmap)#
Where class_map_name is the name of the class map. The match-all keyword is the default, and
specifies that traffic must match all criteria to match the class map. The match-any keyword
specifies that the traffic matches the class map if it matches at least one of the criteria. The CLI
enters class-map configuration mode, where you can enter one or more
match commands.
b. (Optional) To add a description to the class map, enter the following command:
hostname(config-cmap)# description string
c.
(Optional) To match a filename for FTP transfer, enter the following command:
hostname(config-cmap)# match [ not ] filename regex [ regex_name |
class
regex_class_name ]
Where the regex_name is the regular expression you created in Step 1 . The class regex_class_name
is the regular expression class map you created in Step 2 .
d.
(Optional) To match a file type for FTP transfer, enter the following command:
hostname(config-cmap)#
match
[
not
]
filetype regex
[ regex_name |
class
regex_class_name
]
Where the regex_name is the regular expression you created in Step 1 . The class regex_class_name
is the regular expression class map you created in Step 2 .
e.
(Optional) To disallow specific FTP commands, use the following command:
hostname(config-cmap)# match [ not ] request-command
ftp_command
[
ftp_command
...]
Where ftp_command with one or more FTP commands that you want to restrict. See Table 25-3 for
a list of the FTP commands that you can restrict.