If your computer network is your castle, the network firewall is the portcullis\u2014the main gate responsible for regulating the flow of incoming and outgoing network traffic. It\u2019s part barrier, part screening mechanism, separating your network from third-party networks and blocking unauthorized access.<\/p>\n\n\n\n
To answer the question\u2014what is a firewall?\u2014in-depth, this guide covers the benefits of a firewall, how it works to strengthen your cyber defenses, and different types of firewalls you can use to monitor your network.<\/p>\n\n\n\n\n\n
In the 19th century, a firewall was a physical barrier meant to prevent fire from spreading from structure to structure. Later, in automobiles, it was a metal barrier that separated the engine compartment from the passenger cabin.<\/p>\n\n\n\n
The phrase was eventually co-opted by the computing industry to refer to a digital security system that places a barrier between a trusted network and an untrusted network like the internet.<\/p>\n\n\n\n
Technologically speaking, a firewall is the outermost layer of a cybersecurity framework. It monitors network traffic inflows and outflows and determines whether data packets are allowed or restricted per a defined set of security rules.<\/p>\n\n\n\n
As the first line of defense against malicious traffic, a firewall guards the network entry point (port), where data may be exchanged with foreign devices. Every single data file you request from an internet source will be logged and processed by the firewall.<\/p>\n\n\n\n
The most basic form of firewall is a packet-filtering firewall. But to understand how it works, we first need to define packets.<\/p>\n\n\n\n
To transmit data across the internet, data files must be broken down into smaller pieces, typically ranging from 500 bytes to 64KB, with an average size of 1500 bytes. These are referred to as data packets, which are the snippets of data sent over the Transmission Control Protocol\/Internet Protocol (TCP\/IP) network.<\/p>\n\n\n\n
Before they can be assembled into their final form, the firewall must analyze each data packet and confirm that a device or system within your network actually requested it.<\/p>\n\n\n\n
For this example, think of a firewall as a security guard at a concert. In order to enter the venue, they may ask you to funnel through a chokepoint, display tickets and proof of identification, and then request that you pass through a metal detector. A firewall functions similarly, scrutinizing each data packet to determine:<\/p>\n\n\n\n
If denied, the data packet is returned to the sender. But in the more likely scenario that the data packet is dropped, the data disappears altogether.<\/p>\n\n\n\n
Understanding the benefits of firewall security is how you can keep your network safe from bad actors and malicious activity. Firewalls may only serve as one facet of your cybersecurity defenses, but they play an essential role in helping you:<\/p>\n\n\n\n
Firewalls reference pre-established policies and rulesets to decide whether a packet should be accepted, denied, or dropped. To work as intended, the security policy must clearly define how the firewall should handle traffic relating to various factors like IP addresses, address ranges, applications, protocols, and content types. Per the National Institute of Standards and Technology’s (NIST) Guidelines on Firewalls and Firewall Policy:<\/p>\n\n\n\n
\u201cExamples of policy requirements include permitting only necessary Internet Protocol (IP) protocols to pass, appropriate source and destination IP addresses to be used, particular Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) ports to be accessed, and certain Internet Control Message Protocol (ICMP) types and codes to be used.”<\/em><\/p>\n\n\n\n For most rulesets, it\u2019s better to restrict all traffic except that which is expressly permitted by the firewall policy. This decreases the likelihood of an attack occurring. It also reduces the network’s traffic volumes.<\/p>\n\n\n\n The NIST framework recommends three specific actions:<\/p>\n\n\n\n A firewall will fall into one of two categories: software (host-based) or hardware (network-based).<\/p>\n\n\n\n Software firewalls are programs installed onto devices that regulate incoming traffic via port numbers and applications, whereas hardware firewalls are physical devices installed to separate your network and gateway. According to Boston University:<\/p>\n\n\n\n \u201cNetwork-based firewalls may be installed at the perimeter, or edge, of a network to protect a corporation from hosts on the Internet, or internally to protect one segment of the community from another, such as separating corporate and residential systems, or research systems from marketing systems.\u201d<\/em><\/p>\n\n\n\n There are also several subcategories of firewalls that have emerged over the years, including:<\/p>\n\n\n\n A firewall is your company\u2019s first line of cyber defense. It plays an essential role in protecting your network. By monitoring, screening, and restricting traffic, a firewall helps ensure that only authorized data can gain access.<\/p>\n\n\n\n At WP Engine, we seek to instill robust security measures to create a secure WordPress hosting<\/a> environment without hampering website performance. Our team uses one of the best firewalls to prevent hackers<\/a> that block more than 26 billion attacks each year. Armed with proactive threat detection and a host of plugin, core, and PHP updates, the system automatically detects and directs good, bad, and malicious traffic.<\/p>\n\n\n\n But the system isn\u2019t just automated. We also provide a live security team that practices best-in-class standards to continuously monitor your risk and compliance landscape. If a security issue arises, we provide proactive alerts so that you can stop bad actors in their tracks.<\/p>\n\n\n\n Do you need an enterprise-grade solution? Our Global Edge Security provides:<\/p>\n\n\n\n With dedicated and advanced security, WP Engine provides the features you need for enterprise WordPress<\/a> websites that are better, faster, and safer.<\/p>\n\n\n\nHow do you create a robust policy and ruleset?<\/h3>\n\n\n\n
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Types of Firewalls<\/h2>\n\n\n\n
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WP Engine\u2019s Proprietary Firewall<\/h2>\n\n\n\n
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