Cisco Systems IP Options Inspection

11-41
Cisco ASA Series Firewall ASDM Configuration Guide
Chapter11 Configuring Inspection of Basic Internet Protocols
IP Options Inspection
•Source IP Address—Select to match the source IP address of the IM message. In the Value fields,
enter the IP address and netmask of the message source.
•Destination IP Address—Select to match the destination IP address of the IM message. In the Value
fields, enter the IP address and netmask of the message destination.
•Filename—Select to match the filename of the IM message. In the Value fields, click the Regular
Expression or Regular Expression Class option and select an expression from the drop-down list.
See Configuring Regular Expressions, page20-11 in the general operations configuration guide.
Step9 Click OK to save the criteria. The Add Instant Messaging (IM) Match Criterion dialog box closes and
the criteria appears in the Match Criterion table.
Step10 Click OK to save the class map.
Select IM Map
The Select IM Map dialog box is accessible as follows:
Add/Edit Service PolicyRule Wizard > Rule Actions > Protocol Inspection Tab > Select IM Map
The Select IM Map dialog box lets you select or create a new IM map. An IM map lets you change the
configuration values used for IM application inspection. The Select IM Map table provides a list of
previously configured maps that you can select for application inspection.
Fields
•Add—Opens the Add Policy Map dialog box for the inspection.
IP Options Inspection
This section describes the IP Options inspection engine. This section includes the following topics:
•IP Options Inspection Overview, page11-41
•Configuring IP Options Inspection, page11-42
•Select IP Options Inspect Map, page11-43
•IP Options Inspect Map, page 11-44
•Add/Edit IP Options Inspect Map, page11-44
IP Options Inspection Overview
Each IP packet contains an IP header with the Options field. The Options field, commonly referred to as
IP Options, provide for control functions that are required in some situations but unnecessary for most
common communications. In particular, IP Options include provisions for time stamps, security, and
special routing. Use of IP Options is optional, and the field can contain zero, one, or more options.
You can configure IP Options inspection to control which IP packets with specific IP options are allowed
through the ASA. Configuring this inspection instructs the ASA to allow a packet to pass or to clear the
specified IP options and then allow the packet to pass.
IP Options inspection can check for the following three IP options in a packet: