44-6
Cisco ASA 5500 Series Configuration Guide using the CLI
Chapter44 Configuring Inspection for Voice and Video Protocols
H.323 Inspection
•Static PAT may not properly translate IP addresses embedded in optional fields within H.323
messages. If you experience this kind of problem, do not use static PAT with H.323.
•H.323 application inspection is not supported with NAT between same-security-level interfaces.
•When a NetMeeting client registers with an H.323 gatekeeper and tries to call an H.323 gateway that
is also registered with the H.323 gatekeeper, the connection is established but no voice is heard in
either direction. This problem is unrelated to the ASA.
•If you configure a network static address where the network static address is the same as a
third-party netmask and address, then any outbound H.323 connection fails.
Configuring an H.323 Inspection Policy Map for Additional Inspection Control
To specify actions when a message violates a parameter, create an H.323 inspection policy map. You can
then apply the inspection policy map when you enable H.323 inspection.
To create an H.323 inspection policy map, perform the following steps:
Step1 (Optional) Add one or more regular expressions for use in traffic matching commands according to the
“Creating a Regular Expression” section on page 13-12. See the types of text you can match in the match
commands described in Step3.
Step2 (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 13-15.s
Step3 (Optional) Create an H.323 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-connection, reset,
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 h323 [match-all | match-any] class_map_name
hostname(config-cmap)#
Where the 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
Where string is the description of the class map (up to 200 characters).
c. (Optional) To match a called party, enter the following command:
hostname(config-cmap)# match [not] called-party regex {class class_name | regex_name}