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Example: Configuring a Filter to Match on Port and Protocol Fields

This example shows how to configure a standard stateless firewall filter to match on destination port and protocol fields.

Requirements

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

Overview

In this example, you configure a stateless firewall filter that accepts all IPv4 packets except for TCP and UDP packets. TCP and UDP packets are accepted if destined for the SSH port or the Telnet port. All other packets are rejected.

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.

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 filter1:

  1. Create the IPv4 stateless firewall filter.

  2. Configure a term to accept all traffic except for TCP and UDP packets.

  3. Configure a term to reject packets to or from the 192.168/16 prefix.

  4. Configure a term to accept packets destined for either the SSH port or the Telnet port.

  5. Configure the last term to reject all packets.

Apply the Stateless Firewall Filter to a Logical Interface

Step-by-Step Procedure

To apply the stateless firewall filter to a logical interface:

  1. Configure the logical interface to which you will apply the stateless firewall filter.

  2. Configure the interface address for the logical interface.

  3. Apply the stateless firewall filter to the logical interface.

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 filter1 operational mode command.