What is a stateful inspection firewall (SIF) and why should I care? Here are the best answers.
What Is Stateful Inspection Firewall?
Stateful Inspection Firewall is a type of firewall that can track the state of network connections. When a network packet travels through an interface of the firewall, it is compared to the list of connection states. If a state is found that matches the packet, then it is allowed to pass.
If no matching state is found, then either the packet is blocked or sent to a different interface for processing. A firewall with a stateful inspection can perform tasks like filtering. So, this includes blocking, permitting, or modifying network packets based on specified rules and traffic shaping.
It is prioritizing certain types of traffic based on bandwidth availability. If you have ever experienced traffic shaping with your DSL or cable modem, then you have already seen what a stateful inspection firewall can do.
Understanding Stateful Packet Inspection
Stateful Packet Inspection (SPI) is a form of firewall technology that examines each incoming and outgoing packet against a pre-defined security policy. Also, the result is that SPI-enabled firewalls can enforce policies on both inbound and outbound traffic. Whereas traditional firewalls only focus on protecting against incoming threats.
This extra functionality allows SPI-enabled firewalls to do more than just protect against common threats to your network: Also, it provides real-time audit capabilities, intrusion prevention, and application control, as well as other benefits.
Stateful Inspection Firewall Cons
Here are the disadvantages of the Stateful Inspection Firewall:
1. High Cost: The high cost is its biggest disadvantage. We know that a firewall is supposed to protect the whole network from outside threats and it utilizes a lot of resources to do that. But we can’t deny the fact that an enterprise-class enterprise firewall will cost you thousands of dollars.
2. Complex Configuration: You need to spend a lot of effort understanding how it works and how to configure it.
3. Difficult to Scale: Since SPI-enabled firewalls cost much, most of us don’t have the budget to purchase multiple SPI-enabled firewalls at once.
4. Difficult to Troubleshoot: It’s much more complex than a dumb firewall. If you have any problem with it, you need to spend a lot of time and energy troubleshooting it.
Stateful Inspection Firewall Advantage
Some people think it’s not good while others think it’s good. Here are some pros:
1. Better security: Since it performs deep packet inspection, it can detect and block/drop many kinds of attacks. This cannot be detected by a normal/dumb firewall using signature detection only.
2. Application control: It can detect and block/drop many kinds of application layer attacks like buffer overflow attacks, command injection attacks, etc.
3. Real-time Audit Trail: It keeps track of all activities such as blocked sessions, dropped packets, etc.
4. It’s scalable: You can add more interface cards (NICs) and CPU card(s) to increase its throughput, capacity, and performance.
5. Easy deployment: You just need to install its software on your server and plug its interface card(s) (NICs) into your network.