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Example: Configuring a Filter to Accept OSPF Packets from a Prefix

 

This example shows how to configure a standard stateless firewall filter to accept packets from a trusted source.

Requirements

No special configuration beyond device initialization is required before configuring this example.

Overview

In this example, you create a filter that accepts only OSPF packets from an address in the prefix 10.108.0.0/16, discarding all other packets with an administratively-prohibited ICMP message

Configuration

The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode.

To configure this example, perform the following tasks:

CLI Quick Configuration

To quickly configure this example, copy the following configuration commands into a text file, remove any line breaks, and then paste the commands into the CLI at the [edit] hierarchy level.

Configure the Stateless Firewall Filter

Step-by-Step Procedure

To configure the stateless firewall filter ospf_filter:

  1. Create the filter.

  2. Configure the term that accepts packets.

  3. Configure the term that rejects all other packets.

Apply the Firewall Filter to the Loopback Interface

Step-by-Step Procedure

To apply the firewall filter to the loopback interface:

  1. Configure the interface.

  2. Configure the logical interface IP address.

  3. Apply the filter to the input.

Confirm and Commit Your Candidate Configuration

Step-by-Step Procedure

To confirm and then commit your candidate configuration:

  1. Confirm the configuration of the stateless firewall filter by entering the show firewall configuration mode command. If the command output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

  2. Confirm the configuration of the interface by entering the show interfaces configuration mode command. If the command output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

  3. If you are done configuring the device, commit your candidate configuration.

Verification

To confirm that the configuration is working properly, enter the show firewall filter ospf_filter operational mode command.