Tech Bytes
Network Firewalls In A Nutshell
By Murithi Magiri
The year 2025 started on tragic note in California, a series of ferocious wildfires erupted and roared across the region wreaking havoc, lives were lost and large swathes of property destroyed. It will take time to recover and rebuild. It is for such reasons that firewalls were built. A firewall is a wall meant to confine a fire within a line of adjacent buildings. Firewalls were used later to refer to the metal sheet separating engine and passenger compartments in vehicles and aircrafts. Basically, a firewall is a wall of defense.
In computing networks, a network firewall is a security device designed to monitor, filter, and control incoming and outgoing network traffic based on predetermined security rules. Its primary purpose is to establish a barrier between a trusted internal network and untrusted external networks, such as the internet.
Think of it as a security guard standing at the entrance of your building to filter access, think of a security service agent. In networks firewalls check the credentials of everything that tries to enter or exit.
Firewalls are the bedrock of network security, shielding the network from unauthorized access and harmful activities. They prevent bad actors- hackers, bots, and other threats- from infiltrating a private network to steal sensitive data. Without this protection, virtually anyone could enter and do as they please, posing significant risks to data integrity and privacy.
Firewalls can be categorized as either network-based or host-based. Networkbased firewalls are placed between two or more networks, they can be a hardware appliance running on a special purpose hardware- this has been the most common, they can also be a software running on a general-purpose appliance like a desktop computer, or they can be a virtual appliance running on a virtual machine. Host-based firewalls are deployed directly on the host itself to control network traffic or other computing resources. This can be a daemon or service as a part of the operating system or an agent application for protection.
Firewalls come in various forms, each with its unique features and functionalities.
Packet filtering firewalls
These firewalls inspect each packet of data that passes through them and filter them based on parameters like source and destination IP addresses, port numbers, and protocol types. They are relatively simple and cost-effective but less effective against sophisticated attacks.
In computing networks, a network firewall is a security device designed to monitor, filter, and control incoming and outgoing network traffic based on predetermined security rules. Its primary purpose is to establish a barrier between a trusted internal network and untrusted external networks, such as the internet.
Stateful inspection firewalls
These firewalls monitor all activity from the opening of a connection until it is closed. They make filtering decisions based on both administrator-defined rules and context, using information from previous connections and packets belonging to the same connection.
Proxy firewalls
Acting as intermediaries for internal and external networks, proxy firewalls
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