What are the different types of firewalls?

To choose the proper firewall for your system to protect the inputs and outputs in the design and install it on your system, you must first get acquainted with  different types of firewalls  so that you can choose the right kind of firewall for your system. There are different types of firewalls, each of which can be used for other systems with different needs.

- In general, we can say that  firewalls are different in terms of software and hardware, and we can generally divide them into four categories:

- Packet Filtering, which is known as data packet refiners and analyzers.

Circuit Level Gateways are known as flow level gates in the system.

- Application-level gateways, known as  software-level gateways in systems.

- Stateful inspection Firewalls, which are the same as status monitoring firewalls.

The first group of firewalls: Packet Filtering

This sort of firewall is one of the first classes of firewalls created in 1980. These firewalls, which were also the first of their kind, could be run using a simple router and protect the system. In this kind of firewall, which could use a simple router to  protect security operations and systems, they first identified the data path and then took the necessary security measures for that data. The simple routers used in these firewalls could act as a filter for data. The routers responsible for filtering the data packets can be in the network layer of OSI type or the IP layer of TCP / IP type. In this sort of firewall, all data packets were checked using some security measures and rules, and after checking, security measures were done to further protect the system. After the data packets were examined, if the packets were clean and intact, they were allowed to enter and log in, but they were prevented from entering the system if the data packets were not clean. In other words, safe data packets were allowed to enter, but infected data packets were banned and could not be imported.

The advantages of this class of firewall are listed below:

- Although these types of firewalls were simple, they were less expensive or more cost-effective.

- These  types of firewalls affect network traffic and performance.

- There is no need to create special configurations when using these firewalls.

- Although rejecting this sort of firewalls used simple and basic features, they were widely used, and their performance has been the best. In other words, we can say that due to their simple and basic features, they have a good and excellent performance.

In addition to having good performance compared to using simple features, their performance speed is also high.

In addition to having advantages, they also have some disadvantages, which are listed below:

This sort of firewall is basic and uses simple features. With the advancement of technology and the literacy of hackers, hackers can easily identify the weaknesses and vulnerabilities of this sort of firewall and then attack them through it. And enter systems. So, we can say that because of their simplicity, their vulnerabilities can be easily identified by hackers.

In this style of firewall, there is no  application network layer, which is why it is not possible to decide on the content of the packages. For example, we can say that each package may have contaminated content and data, but there are no tools and facilities to deal with them.

- In this sort of firewall, it is impossible to authenticate, and systems that send data packets cannot be authenticated. It should be noted that even if you use a packet of firewalls or encrypt the system, it may not work well.

- Another disadvantage of this type of firewall is that it cannot show the status, called Stateless. In using this  type of firewall, no report of all actions performed for the user is reported, and the user cannot see its status. There is a shortage that if an attack occurs or some network traffic occurs, we cannot identify them.

The second group of firewalls: Circuit level Gateways

These firewalls can work in the transfer layer with  OSI and TCP models. These types of firewalls can be used in TCP connections. Of course, it should be noted that in this type of firewall, handshaking between data packets is also checked to determine whether the session is valid or not.

How this type of firewall works is as follows:

- Unique session identifier that is available in this type of firewall causes the user to connect to the network through an input port. After that, the possibility of multiple logins for the user is limited. This means that users cannot log in multiple times and only log in through one input port.

- The sequence of data and information in this type of firewall is examined.

- All its addresses are examined in terms of origin and destination.

- The number of each port is fixed and does not change.

- Also, the information of packets that have been inserted or removed from the network card is stored.

What are the benefits of Circuit level Gateways firewall?

In this ilk of firewall, the working speed is very high, and it can be said that it is one of the firewalls that have high-speed performance. Of course, it is worth noting that because not much analysis and analysis is done on data and packages, it is high speed.

What are the disadvantages of Circuit level Gateways firewall?

One of the main disadvantages of this ilk of firewall is that it cannot restrict access to TCP subset protocols. In addition, it is good to know that in this type of firewall, we had more features than the previous firewall. Still, this type of firewall cannot carefully examine the data packets that pass through.

The third group of firewalls: Application-level Gateways

In this ilk of firewall, information and data are monitored in the seventh layer of OSI and the fifth layer of TCP / IP. In using this ilk of firewall, we are dealing with a proxy, and I also use it. Of course, it should be noted that this ilk of firewall has some similarities to the previous firewall, but it also has some differences.

What are the benefits of an Application-Level gateway firewall?

It should be noted that this ilk of firewall has a high level of security compared to the first ilk of firewall.

Using this class of firewall, we can have a complete report of all incoming network traffic.

What are the disadvantages of Application-level gateways firewalls?

One of the disadvantages of this class of firewall is that it is complex and has a complex security system. For this reason, its complexity causes the overloads to increase. In addition, the complexity of the

security system of this kind of firewall may cause some security holes. These security holes can be further widened when the system is connected to the Internet and has important information resources.

The fourth group of firewalls: Stateful Inspection Firewall

It is worth noting that if we combine the three types of firewalls listed above, we will reach the Stateful Inspection Firewall. In using this style of firewall, we have three levels of security in firewalls. Data monitoring is done in layer three and IP layers.

What are the benefits of a stateful multilayer inspection?

One of the most important advantages of this kind of firewall is that it can dynamically scan all ports and sessions. With this feature, it is possible to review and manage individual sessions.

What are the disadvantages of a Stateful multilayer inspection firewall?

One of the most important disadvantages of this kind of firewall is that it has a higher cost, and in addition to the additional costs, we must use some more hardware and software.