The Source and Destination criteria of an access rule define the security zones (interfaces) through which the traffic passes, the IP addresses or the country or continent (geographical location) for the IP address, or the protocols and ports used in the traffic. The default is any zone, address, geographical location, protocol, and port.
To modify the source or destination conditions in an access control rule you can edit the rule using the procedure in Configure the Firepower Threat Defense Access Control Policy. Simple edits may be performed without entering edit mode. From the policy page, you can modify a condition in the rule by selecting the rule and clicking the + button within the source or destination condition column and selecting a new object or element in the popup dialog box. You can also click the x on an object or element to remove it from the rule.
You can use the following criteria to identify the source and destination to match in the rule.
Source Zones, Destination Zones
The security zone objects that define the interfaces through which the traffic passes. You can define one, both, or neither criteria: any criteria not specified applies to traffic on any interface.
- To match traffic leaving the device from an interface in the zone, add that zone to the Destination Zones.
- To match traffic entering the device from an interface in the zone, add that zone to the Source Zones.
- If you add both source and destination zone conditions to a rule, matching traffic must originate from one of the specified source zones and egress through one of the destination zones.
Use this criteria when the rule should apply based on where the traffic enters or exits the device. For example, if you want to ensure that all traffic going to inside hosts gets intrusion inspection, you would select your inside zone as the Destination Zones while leaving the source zone empty. To implement intrusion filtering in the rule, the rule action must be Allow, and you must select an intrusion policy in the rule.
Note: You cannot mix passive and routed security zones in a single rule. In addition, you can specify passive security zones as source zones only, you cannot specify them as destination zones.
Source Networks, Destination Networks
The network objects or geographical locations that define the network addresses or locations of the traffic.
- To match traffic from an IP address or geographical location, configure the Source Networks.
- To match traffic to an IP address or geographical location, configure the Destination Networks.
- If you add both source and destination network conditions to a rule, matching traffic must originate from one of the specified IP addresses and be destined for one of the destination IP addresses.
When you add this criteria, you select from the following tabs:
- Network—Select the network objects or groups that define the source or destination IP addresses for the traffic you want to control. You can use objects that define the address using the fully-qualified domain name (FQDN); the address is determined through a DNS lookup.
- Geolocation—Select the geographical location to control traffic based on its source or destination country or continent. Selecting a continent selects all countries within the continent. Besides selecting geographical location directly in the rule, you can also select a geolocation object that you created to define the location. Using geographical location, you could easily restrict access to a particular country without needing to know all of the potential IP addresses used there.
Note: To ensure that you are using up-to-date geographical location data to filter your traffic, Cisco strongly recommends that you regularly update the geolocation database (GeoDB).
Source Ports, Destination Ports/Protocols
The port objects that define the protocols used in the traffic. For TCP/UDP, this can include ports. For ICMP, it can include codes and types.
To match traffic from a protocol or port, configure the Source Ports. Source ports can be TCP/UDP only.
To match traffic to a protocol or port, configure the Destination Ports/Protocols. If you add only destination ports to a condition, you can add ports that use different transport protocols. ICMP and other non-TCP/UDP specifications are allowed in destination ports only; they are not allowed in source ports.
To match traffic both originating from specific TCP/UDP ports and destined for specific TCP/UDP ports, configure both. If you add both source and destination ports to a condition, you can only add ports that share a single transport protocol, TCP or UDP. For example, you could target traffic from port TCP/80 to port TCP/8080.