What is network security? Types, threats and how it works

The traditional network perimeter is gone. As organizations embrace cloud services, hybrid work and connected devices, network security has evolved from protecting a fixed boundary to securing connections everywhere.

Network security protects the infrastructure, services and data that move across a network. It works alongside endpoint, identity and application security to defend the systems connected to that network. But as information technology advanced, the network edge—the key perimeter for network administrators—simply became one of dozens of potential attack surfaces. What used to be a clearly defined perimeter became more complicated, requiring layered defenses that protect endpoints, users and entities at multiple points.

Arguably, network security, along with antivirus tools, access control, operating-system security, and cryptography, formed the bedrock of modern cybersecurity—a far broader practice. Network security is now an invaluable component of overall cybersecurity. 

Key points of this article:

• In recent years, the network perimeter has become more porous due to cloud, SaaS, and unmanaged devices.
• Existing controls and policies have countered many threats, but many organizations have strengthened security by adopting Zero Trust architecture.
• Likewise, strong endpoint security improves resilience against network-borne attacks and provides defenders with valuable additional visibility.
• Best practice defenses should start with policies and procedures, not expensive tool purchases.

What is network security?

Network security aims to protect both the data travelling across a network and the components of the network itself. As the complexity of networks and computers, software and services running over them has increased, so has the practice. 

As time has passed, most organizations’ networks have become more complicated and porous. Attackers have become more numerous, and gained more tools that allow more sophisticated attacks. Organizations expanded their use of technologies such as VPNs, segmentation, firewalls, IDS and IPS as networks became more distributed.

The challenge is far from theoretical. ESET's research found that 45% of surveyed organizations experienced at least one cybersecurity incident in the previous 12 months, highlighting how frequently modern attackers find opportunities to exploit weaknesses across increasingly distributed environments.

As well as technology, network security policies and approaches have also become far more sophisticated and complex. 

From fairly rudimentary roots protecting the earliest networks, network security now represents a key element of strong cybersecurity practice, protecting and connecting users, entities, devices, data and applications. Network security has evolved beyond protecting systems, data and users on a Local Area Network to cloud environments, SaaS applications and remote sites—including the laptop tethered to a less-than-secure Wi-Fi access point in a coffee shop.

Is this the same as a “network security key”? 

No: that’s a Wi-Fi password. Network security is the practice of securing a network’s infrastructure and the data that moves across it, and is part of a healthy cybersecurity practice in almost every organization. A network security key is one of the credentials used to connect to a network.

How network security works

Network security is built around the CIA Triad: confidentiality, integrity and availability. 

• Confidentiality in the context of network security means making sure that only those entities with the correct authorization have access to the data, information and network resources. Historically, this meant having the right username and password, but over time, authentication has become more sophisticated: more stringent access controls, encryption of data in transit and at rest and so on.
• Integrity is concerned with ensuring the data and the network it travels across stays in the state it should. That means taking steps to prevent both of those things being altered without permission: the use of checksums and hashing to ensure data is unchanged, and locking down network controls to stop unauthorized changes.
• Availability is concerned with ensuring networks are resilient against anything from Denial of Service (DoS) attacks through to power cuts and interns unplugging the wrong thing at the wrong time.

There’s no single tool, control or capability to do one or all of these things. Instead, network security takes a layered approach for defense in depth. 

This is both a strong defensive concept and a pragmatic outcome. A layered defense that combines endpoint protection, network segmentation, firewalls, and IDS/IPS technologies is more resilient if any individual control fails. It’s also a sensible means to add extra layers of defense on top of existing protections as they become available, affordable or necessary.

The main types of network security

As we’ve seen, network security isn’t a single tool, but a combination of multiple tools and controls. These are tied together with operating practices to meet the needs of the organization. The different capabilities address different challenges. The below table presents the most significant controls in summary.

Common network security threats

Threats by attacker objective

It’s worth looking at threats from the perspective of the attacker’s intent, and secondly from the perspective of attack stages.

Extortion is probably the most common motivation; ransomware continues to grow in volume year after year. Verizon's 2026 DBIR found ransomware in 48% of breaches. Separately, the report found third-party involvement in 48% of breaches, reflecting the growing risk associated with vendors and service providers. Common techniques used in ransomware attacks include SMB exploitation, Microsoft’s NT LAN Manager (NTLM) authentication, and phishing, making strong network security vital.

Research suggests organizations may be worrying about the wrong threats. In ESET's SMB Cyber Readiness Index 2026, AI-powered malware ranked as the top concern among respondents (31%), yet phishing campaigns (26%), unpatched vulnerabilities (23%), lack for security monitoring (22%), and weak passwords (20%) were reported more frequently as causes of actual incidents.

Denial of service and disruption can be linked to extortion, activism or trolling, but the aim is the same: deny the organization, its employees and any users or customers the ability to communicate. Regardless, Denial of Service (DoS) and Distributed Denial of Service (DDoS) attacks are one of the most visible threats that strong network security can help alleviate or deter.

Data theft or exfiltration is another common motivation, and sees attackers target the network layer to carry out their aims. This can involve man-in-the-middle (MITM) attacks or traffic spoofing, which look to intercept or redirect data in transit.

Threats across the attack lifecycle

Attack stages also provide insight into threats and how network security with defense in depth helps. Different techniques can be defeated and detected by various elements of strong network security. 

Attackers’ attempts to gain access and establish a foothold—or buy such access from dedicated Access Brokers—represent a key challenge for network security and cybersecurity in general. IDS and IPS, as well as web and email security, all play a role from a network security perspective in denying initial approaches, including social engineering. It’s worth noting that one of the best defenses against these attacks is effective training to reduce the number of people clicking on something they shouldn’t, of course. 

But equally important is the use of NDR and endpoint detection (amongst others) to look for unauthorized device use or access, and suspicious internal traffic that might suggest scanning, C2 activity or lateral movement. Firewalls and NGFW also play a role in detecting similar behavior attempting to scan or infiltrate from outside the perimeter, but this doesn’t cover the other attack surfaces we’ve mentioned.

We’ve already mentioned lateral movement, and this is a key stage for attackers, and a key detection point for defenders. Segmentation and micro segmentation help here, but strengthening security by adopting Zero Trust architecture has also become critical. 

It’s worth flagging another area of concern. Many attacks rely on botnets and Command and Control (C2) infrastructure to maintain access to compromised systems and coordinate malicious activity. These capabilities can support multiple stages of an attack, including persistence, lateral movement, data exfiltration and the delivery of additional payloads.

Network security in 2026—the perimeter dissolved

As computer networks grow in size and complexity, their attack surface expands non-linearly. Every new endpoint, identity, cloud service, and API creates a fresh potential entry point for attackers, along with new interdependencies to exploit.

In the early days, firewalls at the perimeter of the organization’s network, coupled with single factor authentication (i.e., a username and password) and a decent antivirus package on every PC were ‘enough’. This hasn’t been sufficient for a very long time. 

The traditional network perimeter has largely dissolved, forcing organizations to secure identities, endpoints, cloud services, and applications alongside conventional network boundaries. Despite growing confidence in their resilience, many organizations continue to face frequent security incidents. ESET’s research found that 75% of respondents were confident in their resilience, while 45% reported experiencing at least one cybersecurity incident during the previous year. 

This gap illustrates how confidence alone isn’t a reliable indicator of security readiness, reinforcing the need for strong visibility, segmentation, monitoring and identity controls

In these conditions, close integration between network, endpoint and identity security is critical. Endpoints have become a major source of security telemetry and enforcement, giving defenders valuable visibility into activity that may not be observable from the network alone. Technologies such as Endpoint Protection Platform (EPP), Endpoint Detection and Response (EDR) and Managed Detection and Response (MDR) complement network security by detecting and responding to threats at the device level.

Network security best practices

What should organizations look to do with their networks to create a baseline of strong security? Often, updating processes and ensuring policies are in place should come a long way before any spending on shiny tools. Let’s break it down:

Segment the network

HR doesn’t need access to the manufacturing team’s network for the most part—and you certainly don’t want workers or attackers from outside sniffing around the payroll server. Workloads, servers, users and apps don’t need to be able to access everything else, so enforce least privilege access. Good endpoint monitoring can rescind access for devices or accounts that are suspected of compromise.

Enforce least privilege / Zero Trust

Closely linked to segmentation is the application of Zero Trust architecture across all devices and accounts. It can significantly reduce opportunities for unauthorized access and lateral movement.

Harden your protocols

Some protocols shouldn’t have free reign—they’re far too helpful to attackers looking to move around within a network. SMB v1 should be locked down entirely, and Kerberos remains a more secure form of authentication than NTLM, so only use the latter if you absolutely have to. 

Patch now

No ifs, no buts: keep your patching up to date for everything touching your network, from the APs and switches on up, which includes also network-connected lightbulbs. There is good reason for urgency: ESET research identified unpatched vulnerabilities as the second most common cause of security incidents, cited by 23% of respondents.

Encrypt

Ensure all data in transit is encrypted using modern protocols, alongside robust encryption at rest. For sensitive compute environments, confidential computing can be added to secure data in use.

Protect your endpoints

Fileless attacks such as suspicious RDP usage or SMB exploits often look like legitimate traffic to network security tools. Catching this behavior relies on endpoint protection tools that monitor activity directly on the host.

Monitor and log, log, log

The heart of any strong response and remediation effort is digital forensics, and detection is nothing without log analysis. Ensure your cybersecurity team can enjoy deep data from network devices in their SIEM or XDR showing traffic patterns, user and entity behavior and performance. It’ll make effective response a lot easier. A lack of security monitoring contributed 22% of reported incidents, placing it among the most frequently cited causes of compromise.

Back up to build redundancy and resilience

The best defense against a successful ransomware attack remains a full backup, and so it goes with networks, too. Regularly back up configurations, logs and more to bring your network back up quickly.

Conclusion

Network security remains a foundation of cybersecurity, even as the old perimeter gives way to cloud services, remote work and connected devices. The goal is still the same: protect data, control access, maintain availability and limit attackers’ room to move.

Strong protection comes from layered controls working together—from segmentation and Zero Trust to endpoint protection, monitoring, patching and resilient backups. In modern environments, network security is not a standalone discipline at all, rather, a core part of cyber resilience.

FAQs

What is the difference between network security and cybersecurity?

Cybersecurity is the whole discipline of protecting systems, devices and data from attack. Network security is the part of it focused on the network itself: the infrastructure and the traffic moving across it. Network security is one major branch of cybersecurity, alongside endpoint, application, cloud and identity security.

What are the main types of network security? 

The core controls are firewalls, intrusion detection and prevention (IDS/IPS), VPNs, network access control (NAC), and network segmentation. These are increasingly wrapped in a zero-trust model and delivered through frameworks like SASE. Most organizations layer several of these protections on top of each other, rather than relying on any one.

What is a network security key? 

That’s a different thing: a network security key is the password for a Wi-Fi network, not a security discipline. If that’s what you’re after, it’s the passphrase on your router or in your device’s Wi-Fi settings. This article is about how organizations protect their networks.

Why is network security important? 

A network connects almost everything an organization runs, so a single weak point can let an attacker move from one system to many. Good network security limits how far an intruder can get, protects data as it travels, and keeps services available—which is why it’s a foundation of any security program.

Does endpoint security count as network security? 

They overlap. Endpoint protection lives on the device, but several of its controls, like network attack protection and botnet detection, defend against network-borne threats and stop them spreading. As organizations have adopted cloud services, hybrid work and Zero Trust architecture, endpoint and network security have become more closely integrated. They remain distinct disciplines, but they increasingly share telemetry and work together as part of a layered defense strategy.

What are the most common network security threats? 

Unauthorized access, malware and ransomware spreading across the network, lateral movement after an initial breach, botnet command-and-control traffic, exploitation of unpatched services, denial-of-service attacks, and insider misuse. Layered controls plus prompt security patching address a huge number of these issues, but layered defenses and processes are the best approach.