Almost everyone who has a desktop or laptop has heard about or used firewall software to keep it safe. Firewall software was invented in 1989 and has become a standard security practice for about the past fifteen years. For many organizations ranging from private businesses to schools, libraries, and nonprofits of all sizes, firewalls remain one of the first lines of defense against cyberattacks. Yet as more staff and volunteers go remote, are firewalls becoming a relic of the past, or are they still a critical part of your nonprofit’s security strategy?

To answer that question, we’ll take a look at what a firewall is, how it works, and the four types of firewalls that are most widely used today.

What Exactly Is a Firewall?

For many organizational leaders, a firewall is one of those nebulous business givens: You know you need it, but you might need to learn what it is and why you do it. Let’s start at the beginning and answer the not-so-obvious question: What exactly is a firewall? It’s a type of security device that blocks unauthorized users from accessing your network. It’s designed to ensure that cybercriminals can’t steal data from your network or even break into your system to see how it reacts. Today, firewalls are standard on most PC systems, LANs, and private networks.

In layman’s terms, it’s the lock on your front door that restricts access to your building. In theory, it’s there to keep criminals outside and your information safely inside under lock and key.

How Exactly Does It Work?

So how exactly does this small piece of hardware or software manage to block both intruders and malware? We’re going to take a high-level look at how firewalls work without getting too bogged down in the details. 

All data that is sent over a network is broken down into small segments called packets. The receiving computer or network device then takes the packets that are sent and, in essence, puts the pieces back together to reassemble the message.

A firewall works by analyzing all of those incoming packets. It will determine whether the incoming data meets the filter criteria your IT team has put in place and either allow that data to come into your network or block it from entering. Firewall software typically will be loaded with preexisting criteria that will protect your device from obvious intrusion attempts, such as websites that might be hiding malware, hijacking software, or unknown connections. One of the beauties of firewalls is that they also allow your IT team to custom filters, which can block access/packets even if they weren’t originally predefined.

You can see why a firewall would be a wonderful standard security measure for an individual device. A PC or Mac that’s running this type of anti-virus software on a home network typically won’t require more than this. However, when you add the complexity and number of devices that a typical nonprofit deals with, things can get complicated quickly.

Think of all your staff members and volunteers working in your office. They may be using your organization’s desktops as well as their laptops or tablets. They all have cell phones of some sort, and they are using them to connect to your network. Now combine that with any clients you serve and visitors walking in the door for meetings, all of whom have personal devices. If your nonprofit doesn’t have an effective firewall in place, there is literally no lock on the door. Any internet-savvy entity can hop on your network, look around, potentially steal unattended data, and even leave the back door open for their friends to come in after hours. And if they access confidential or financial information from your client or donor system, it can have disastrous consequences.

That’s where your firewall comes in. It monitors each of those connections based on the rules established by your IT experts. Best of all, those rules can vary based on who the user is and what level of access you want to give each of those connections.

Let’s Unpack Packets

“Packets” are shorthand for Transport Control Protocol packets (TCP Packets). Imagine that they are small envelopes that can contain anything people are sending to your team. Those envelopes might contain the text of a message, media like images and video, URLs, or sending and receiving addresses. These TCP packets are flowing into your network much like a flood of information, and the firewall checks each packet for any problems that it detects or for additional data that it is filtering for.

Packets are usually filtered in one of four ways:

  • Packet Filtering – Packets that come into your network and devices are analyzed and filtered by your firewall based on established criteria. Those criteria will vary based on the network security your IT experts set, but they always target malicious data.
  • Circuit Level Gateways – These gateways are designed not to look at content, but to check the security of the connections that are sending the content. When one of your devices initiates a connection with a remote host, these gateways establish a virtual connection on its behalf, thus keeping the identity and IP address of your device hidden, but not checking the packets themselves.
  • Stateful Inspection – These combine the best of the previous two types.  It checks the status of connections and also compares packets to an extensive database of predetermined filters/flags. It examines batches of packets instead of analyzing each incoming/outing going packet. If data does not meet certain criteria, it’s blocked, making this a broader sweep.
  • Proxy Service Filtering – This adds an extra layer of protection. Data that is sent into your system from a network and/or the internet is accessed by your firewall first at a separate IP address, then sent to the requester and requesting system once it clears your filters.

Can You Customize Your Firewall?

Yes, your IT team can customize firewalls for individual computers or networks. This customization determines what a firewall blocks or allows through a series of different characteristics, including:

  • Domain Name – A firewall can filter/block specific domains your IT team adds to its blacklist. This usually stops access to web zones with unsafe or malicious material.
  • IP Address – Every computer or device that connects to the internet has an IP address. Through a firewall, your IT team can block or allow certain IP addresses to access your network or even different sections of your network.
  • Keywords – Some firewalls can target keywords, phrases, or terms that are red-flagged. For example, if an organization doesn’t want volunteers or employees to watch certain types of streaming services in their office, terms related to those URLs can be blocked.
  • Port – Ports are virtual (or sometimes physical) places within an operating system or device where connections start and end. In other words, a port is an entryway or plug where an external device can hook into your system. Since each port has a specific number, firewalls can block access to specific ports or multiple ones.

Your IT specialists can customize your organization’s firewall even more when additional firewalls are placed on hardware devices, switches, and routers. This type of structure allows them to create “layered” networks in which access is restricted or permitted based on the level you assign a particular staff member or role.

That Was Then…

Some organizations may question why they need a firewall if they have moved their data and applications to the cloud instead of a physical facility. The short answer is that it’s even more critical to protect your confidential data from cyberattacks when that data is virtual.

To meet this very real need, your IT team can utilize cloud firewalls, which are software-based, cloud-deployed devices that block or mitigate access to your network. Advantages of cloud-based systems include the ability to manage them from anywhere, scalability, and, if you are subscribing to a firewall as a service company (FWaaS) they will make sure your system is always up to date against the latest threats. A disadvantage is that if your cloud-based firewall provider goes down, your system may do the same, so your IT team should have a backup plan.


While we’ve only scratched the surface here, there are vastly more complex versions of smart and hybrid firewalls available for nonprofits. Yet they all operate from the same basic principle: an established defense that can filter out harmful connections, websites, and packets.

Despite evolving technology, firewalls remain a necessary foundation of your security system. They can block countless bugs, viruses, spam, and malware attacks.  When you combine them with other, more customized cybersecurity measures, your IT team can create a robust system of protection for your networks and data.

If you’re interested in firewall services or other cybersecurity measures, contact us at Cross The Divide. We have a variety of solutions available for nonprofits of all sizes and look forward to customizing a program for you!