Chapter 22 Configuring Connection Settings

Configuring Connection Settings

•Clear Selective Ack—Sets whether the selective-ack TCP option is allowed or cleared.

•Clear TCP Timestamp—Sets whether the TCP timestamp option is allowed or cleared.

•Clear Window Scale—Sets whether the window scale timestamp option is allowed or cleared.

•Range—Sets the valid TCP options ranges, which should fall within 6-7 and 9-255. The lower bound should be less than or equal to the upper bound. Choose Allow or Drop for each range.

Step 8 Click OK.

Configuring Connection Settings

To set connection settings, perform the following steps.

Detailed Steps

Step 1 Configure a service policy on the Configuration > Firewall > Service Policy Rules pane according to Chapter 1, “Configuring a Service Policy.”

You can configure connection limits as part of a new service policy rule, or you can edit an existing service policy.

Step 2 On the Rule Actions dialog box, click the Connection Settings tab.

Step 3 To set maximum connections, configure the following values in the Maximum Connections area:

•TCP & UDP Connections—Specifies the maximum number of simultaneous TCP and UDP connections for all clients in the traffic class, up to 2000000. The default is 0 for both protocols, which means the maximum possible connections are allowed.

•Embryonic Connections—Specifies the maximum number of embryonic connections per host up to 2000000. An embryonic connection is a connection request that has not finished the necessary handshake between source and destination. This limit enables the TCP Intercept feature. The default is 0, which means the maximum embryonic connections. TCP Intercept protects inside systems from a DoS attack perpetrated by flooding an interface with TCP SYN packets. When the embryonic limit has been surpassed, the TCP intercept feature intercepts TCP SYN packets from clients to servers on a higher security level. SYN cookies are used during the validation process and help to minimize the amount of valid traffic being dropped. Thus, connection attempts from unreachable hosts will never reach the server.

•Per Client Connections—Specifies the maximum number of simultaneous TCP and UDP connections for each client up to 2000000. When a new connection is attempted by a client that already has opened the maximum per-client number of connections, the ASA rejects the connection and drops the packet.

•Per Client Embryonic Connections—Specifies the maximum number of simultaneous TCP embryonic connections for each client up to 2000000. When a new TCP connection is requested by a client that already has the maximum per-client number of embryonic connections open through the ASA, the ASA proxies the request to the TCP Intercept feature, which prevents the connection.

Step 4 To configure connection timeouts, configure the following values in the TCP Timeout area:

•Connection Timeout—Specifies the idle time until a connection slot (of any protocol, not just TCP) is freed. Enter 0:0:0 to disable timeout for the connection. This duration must be at least 5 minutes. The default is 1 hour.

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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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