Chapter 28 Using Protection Tools

Configuring the Fragment Size

•Anti-Spoofing Enabled—Shows whether an interface has Unicast RPF enabled, Yes or No.

•Enable—Enables Unicast RPF for the selected interface.

•Disable—Disables Unicast RPF for the selected interface.

Configuring the Fragment Size

By default, the ASA allows up to 24 fragments per IP packet, and up to 200 fragments awaiting reassembly. You might need to let fragments on your network if you have an application that routinely fragments packets, such as NFS over UDP. However, if you do not have an application that fragments traffic, we recommend that you do not allow fragments through the ASA. Fragmented packets are often used as DoS attacks.

To modify the IP fragment database parameters of an interface, perform the following steps:

Step 1 Choose the Configuration > Firewall > Advanced > Fragment pane, choose the interface to change in the Fragment table, and click Edit.

The Edit Fragment dialog box appears.

Step 2 In the Size field, set the maximum number of packets that can be in the IP reassembly database waiting for reassembly. The default is 200.

Step 3 In the Chain field, set the maximum number of packets into which a full IP packet can be fragmented. The default is 24 packets.

Step 4 In the Timeout field, set the maximum number of seconds to wait for an entire fragmented packet to arrive.

The timer starts after the first fragment of a packet arrives. If all fragments of the packet do not arrive by the number of seconds specified, all fragments of the packet that were already received will be discarded. The default is 5 seconds.

Step 5 Click OK.

Step 6 Click Apply.

Step 7 To view the fragment statistics, click Show Fragment. See the “Show Fragment” section on page 28-2for more information.

Show Fragment

The Configuration > Properties > Fragment > Show Fragment pane displays the current IP fragment database statistics for each interface.

Fields

•Size—Display only. Displays the number of packets in the IP reassembly database waiting for reassembly. The default is 200.

•Chain—Display only. Displays the number of packets into which a full IP packet can be fragmented. The default is 24 packets.

Cisco ASA Series Firewall ASDM Configuration Guide

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Cisco Systems ASA 5555-X, ASA 5505, ASA 5545-X, ASA 5585-X, ASA 5580 manual Configuring the Fragment Size, Show Fragment, 28-2
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ASA Services Module, ASA 5555-X, ASA 5545-X, ASA 5585-X, ASA 5580 specifications

Cisco Systems has long been a leader in the field of network security, and its Adaptive Security Appliance (ASA) series is a testament to this expertise. Within the ASA lineup, models such as the ASA 5505, ASA 5580, ASA 5585-X, ASA 5545-X, and ASA 5555-X stand out for their unique features, capabilities, and technological advancements.

The Cisco ASA 5505 is designed for small businesses or branch offices. It provides essential security features such as firewall protection, flexible VPN capabilities, and intrusion prevention. The ASA 5505 supports a user-friendly interface, allowing for straightforward management. Its built-in threat detection and prevention tools provide a layered defense, and with scalability in mind, it can accommodate various expansion options as organizational needs grow.

Moving up the line, the ASA 5580 delivers greater throughput and advanced security features. This model is suited for medium to large enterprises that require robust protection against increasingly sophisticated threats. Its multi-core architecture allows it to manage high volumes of traffic seamlessly while maintaining excellent performance levels. The ASA 5580 also supports application-layer security and customizable access policies, making it highly adaptable to diverse security environments.

The ASA 5585-X further enhances Cisco's security offerings with advanced malware protection and extensive security intelligence capabilities. It incorporates next-generation firewall features, including context-aware security, and supports advanced threat detection technologies. This model is ideal for large enterprises or data centers that prioritize security while ensuring uninterrupted network performance and availability.

For enterprises requiring a balance of performance and security, the ASA 5545-X presents a compelling option. This model features scalable performance metrics, high availability, and integrated advanced threat protection. Coupled with advanced endpoint protection and detailed monitoring capabilities, the ASA 5545-X enables organizations to manage their security posture effectively.

Lastly, the ASA 5555-X blends cutting-edge technologies with strong security infrastructures. It boasts high throughput and the ability to execute deep packet inspections. Its sophisticated architecture supports threat intelligence feeds that provide real-time security updates, making it a powerful tool against modern threats.

Each of these Cisco ASA models brings specific advantages to varied environments. Their integrative capabilities enable businesses to enhance their security postures while benefiting from seamless scalability and management. As cybersecurity threats evolve, these advanced appliances play a vital role in protecting valuable digital assets.
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