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What is a firewall?

The first step in finding the right firewalls to protect your company’s data is to know what kind of firewalls there are. Right now, there are five different types of firewall architectures, broadly speaking:

Packet-filtering firewalls

Stateful inspection firewalls

Circuit-level gateways

Application-level gateways (a.k.a. proxy firewalls)

Next-gen firewalls https://www.compuquip.com/blog/the-different-types-of-firewall-architectures

Packet-filtering

Packet filtering firewalls are intended to inspect traffic at the packet level and determine, based upon pre-configured rule sets, which traffic (actually packets) is allowed to flow in and out of the network.

Stateful Inspection

Firewalls inspecting the state of traffic help to determine the legitimacy of traffic by focusing on the TCP connection status of the traffic. For instance, if a packet is seen that is supposedly a response, but no packet was seen exiting the network to generate that response, it would block due to the fact that the response was not requested.

The packet-filtering and stateful inspection methods are used together, such as in the case of the BSD stateful packet filter, PF. PF is used by many open source firewalls today.

Circuit Level

This type of firewall is similar to stateful inspection, except that there is no analysis of the packet content as in packet-filtering firewalls. Therefore, the session state is all that is looked at before deciding upon the fate of traffic.

Application Level

Application level gateways, or proxies, work at the application layer. They also have the ability to inspect the payload of traffic and determine whether or not traffic should be relayed to the intended application.

Next-Generation Firewalls

I am not sure how long this moniker will last, but the name is given to firewalls which feature next-generation technologies. This definition is not really clear, but basically allows a category for firewalls that go beyond basic packet filtering and session monitoring. Many of these next-gen firewalls include capabilities to classify the application being used in the traffic, as apposed to ports and protocols. This is important, as many applications today use non-standard ports and it may not be easy to classify the traffic without deeper inspection of the packets to determine what the actual payload consists of.

Do I Have a Firewall?

This is a great question for consumers to begin to ask themselves, or their more knowledgeable and experienced technical resources. Most consumers never give a thought to whether or not they have a firewall in place for their networks and devices. Others are certain that the equipment provided by their Internet Service Provider (ISP) are adequate for their needs. The problem is that more and more of our household appliances are becoming Internet-connected and opening us up to more risk. Why is this a problem?

While much of what consumers do on the Internet is not very sensitive, I would like to help you understand the risks that a typical consumer could be open to. Do you do your taxes online or have financial information in a file on your Internet-connected computers? Do you have files such as pictures, documents, or recordings that you would want to protect from prying eyes or from possible loss? You see, there is much more at stake than many people want to consider. You have property that could be in jeopardy and it is no less your responsibility to protect your digital assets than it is for you to lock your house in today’s day and age.

Each of us also has a corporate responsibility to keep attackers from using our computers and connected devices as home bases for further attacks on other Internet users. Hackers typically do not run their scripts and push their malware from their servers hidden deep in their mother’s basement. They take over the assets of corporations and unknowing consumers and launch attacks from these remote assets that they control almost as easily as if they were sitting in your office. We each have a responsibility to ensure that we are not propagating this type of activity.

Now to the question at hand…Do YOU have a firewall? As a consumer, you likely have a router that was provided by your ISP. This router does provide some layer of abstraction from the outside world. It will typically disallow incoming traffic that was not initiated by a user in your home. However, a savvy hacker can navigate his way around many common consumer devices and, since there are so many of them, most of the exploits that take advantage of those devices are most likely well known. So, a router might provide some level of protection, but probably not what you want protecting the assets you care about most.

What Options Are Available?

We have established the fact that consumers would gain value from firewalls. The next question you might have is “what are my options”? That is a great question with a lot of different answers. I would say that there are really two categories to answer that question. First, there are consumer-targeted devices on the market to cater to those who need more of a set-it-and-forget-it approach. While I do not think there is ever an option within network security that allows for complete hands-off approach, there is some benefit to allowing someone else to manage the security for you, much like we depend on our antivirus vendors to put out regular updates to our virus definitions.

Cisco, Netgear, and Sonicwall offer consumer-grade firewalls that will meet most of your needs. Make sure you look for firewalls, gateways, and Unified Threat Management (UTM) appliances and not at routers. Some routers (usually classified as gateways) will offer more advanced features, but what we are looking for here is not simply a NAT router. The following link provides some details on a few devices that would suit most consumers or small businesses:

The next category of firewalls that I would suggest for the more technical consumers are the open source variety. There are many open source projects that have been providing firewall software for consumers for years. Many of these projects allow consumers to use their products for free and they also offer commercial version of their products, for a cost, to paying customers. I personally use OPNsense, but I have also used pfSense in the past. Both of these firewalls are based on the BSD operating system, known for stability and security, and offer all of the features most consumers would want on their firewalls. Please review the following link for other options in the open source variety:

The only thing to keep in mind with open source firewalls is that you might need to provide your own hardware, although some of these open source projects do sell specialized hardware if you choose to go that route. In either case, consumers need to protect themselves and there are many options for security in the home or small office. Please take some time to read the resources provided here and feel free to comment where the community can provide their thoughts and opinions on your options.

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