How a Stateful Firewall Makes Decision
A Stateful firewall is an essential part of your network security. It can make decisions about which packets are legitimate and which ones are not.
Stateful firewalls use a three-step process to determine legitimacy
- Inspection
- Decision
- Action
The inspection phase compares each packet’s header against the rules in the firewall rule set to see if it matches any of them. If so, then the packet moves on to the decision phase for evaluation against more specific criteria that may be based on time or user identity information in addition to content examined during the first phase. Finally, after this second round of evaluation has been done, if all requirements have been met at this point then appropriate action is taken by either letting it through or dropping it.
How does a stateful firewall work?
A stateful firewall is a must have for every network. It is the heart of any security solution as it decides which packets are legitimate and which ones should be dropped. When a packet arrives at the firewall, the firewall looks at it and compares its contents to a set of rules. If this packet does not match any of these rules, then the firewall decides whether or not it should be forwarded on through or rejected completely.
In addition, stateful firewalls can examine packets from both directions in order to accept only authorized connections .The firewall will then do policy lookup on the packet and from there it will decide how this traffic should be handled. If a connection has been previously established, then packets for that session can pass through without having to re-authenticate them each time they are sent. In addition, stateful firewalls also provide effective protection against denial of service attacks .
How are stateful inspection firewalls like packet filtering?
Stateful inspection firewalls are like packet filtering as they both work from the top down. Stateful firewalls inspect packets at a higher level, but also have knowledge of previous sessions to make decisions about further traffic flow. Packet filtering inspects packets at the network layer and makes decisions based only on information in that packet.
Stateful inspection firewalls are also like proxy servers as they both inspect traffic at the application layer. Proxy servers, however, do not make decisions about whether or not packets should be forwarded on through.
Can a firewall apply policy based on the connection state?
A firewall can apply policy based on the connection state, which means it can take a counter-intuitive action. For example, if a request is made to allow ICMP traffic in from one of your hosts and its source port is associated with an active SSH or FTP session then denying that particular type of ICMP packet would be appropriate.
What makes a stateless firewall unidirectional in nature?
A stateless firewall is unidirectional in nature. This means that it does not keep track of any stage of the connection, which makes it very quick to process packets but also limits its effectiveness as a security solution because there’s no way to block packets with malicious intent.
Advantages of Stateful firewall
- More secure than packet filtering firewalls.
- It provides a complete security solution for your network and also protects against the newest threats on the internet.
- A Stateful inspection can provide additional protection to an organization by allowing only authorized users access to critical resources while blocking unauthorized traffic from entering or leaving its perimeters.
- It can also block network traffic that is not legitimate, even if it looks like it has passed inspection.
- Stateful firewalls are essential for any business and you will need them to keep your company safe in the world where cyberattacks happen every day.
- More advanced than packet filtering firewalls, it can prevent systems from being overloaded by malicious traffic.
- The Stateful inspection can provide additional protection to an organization by allowing only authorized users access to critical resources while blocking unauthorized traffic from entering or leaving its perimeters.
Disadvantages of Stateful firewall
- It is more complex than packet filtering firewalls.
- It also takes up more memory, CPU cycles and disk space because it needs to keep track of all connections in order to make decisions about future packets.
- The main disadvantage is that state-based firewalls are computationally more intensive due to the need for memory and storage space, which can slow down performance on large networks with many users or packets flowing through them.
- Another drawback is that if the number of rules becomes too high then the system can become so complex that management becomes an issue.
- Processing power is another factor as the stateful firewall needs to be constantly checking every packet and it can become a bottleneck for performance.
- It has a larger attack surface, which can be exploited by hackers.
Conclusion
Stateful firewalls provide a complete security solution for your network and also protect against the newest threats on the internet. It works on the basis of packet inspection. They are essential for any business and you will need them to keep your company safe in the world where cyberattacks happen every day.
