Network security best practices for enterprise IT teams

Network security encompasses the policies, technologies, and controls that protect an organization's network infrastructure from unauthorized access, misuse, and disruption.

Security teams that focus exclusively on perimeter protection often find that attackers reach internal systems through misconfigured devices, excessive user privileges, or unmonitored lateral movement paths.

Effective network security addresses both sides of that problem: controls that limit who or what can reach a given system, and monitoring that detects misuse of access.

Types of network devices and security solutions

Understanding the devices and tools that comprise an enterprise network helps security teams make informed decisions about placement, configuration, and monitoring, and about who or what each device lets reach the network.

The following are the most common network components organizations manage:

• Bridges once connected two or more hosts or network segments. The technology is now obsolete and no longer deployed in modern environments.
• Hubs once connected local area network (LAN) devices. Their lack of built-in intelligence has made them rare in modern network setups, largely replaced by switches.
• A network switch is the default network appliance connecting computers, servers, printers, and other devices in a LAN. It uses MAC addresses to manage and forward data to specific devices. Unlike a hub, a switch can intelligently direct traffic to reduce network congestion and improve network performance.
• A network router directs data packets between different networks to facilitate internet connectivity and internal network communication. Routers use IP addresses to determine the most efficient path for data packets to travel across networks. They can also provide security features, such as access control lists, to restrict network access.
• A gateway serves as an intermediary for devices on separate networks, enabling them to communicate even when they use different communication protocols.
• A firewall segregates one network from another. Firewalls are available in hardware and software forms and can be integrated into devices such as routers and servers. A common deployment is a dedicated appliance that serves as a barrier between the internal network and the outside world.
• A network access control (NAC) system assesses whether devices trying to access the network meet defined security standards, such as up-to-date antivirus software, system updates, and specific configuration settings, and then grants or denies access accordingly.
• A web filter restricts access to internet content based on predefined criteria. For instance, this type of security solution can block access to malicious or inappropriate websites as defined by an organization's policies.
• A proxy server acts as an intermediary between a user's device and the internet. Proxy servers can mask a user's IP address and filter web requests to block access to malicious sites or content.
• An email filter (spam filter) helps prevent unwanted emails from reaching the user's inbox or delivers emails with potentially malicious hyperlinks and attachments removed. Simple filters use organizational policies or vendor-specified patterns to detect spam; advanced filters employ heuristic methods to identify suspicious patterns.
• DDoS mitigation tools detect distributed denial of service (DDoS) attacks early, absorb the resulting traffic surge, and help pinpoint the attack's origin.
• Load balancers contribute to network security by distributing network traffic evenly across multiple servers. For instance, they help prevent any single server from becoming overloaded during a DDoS attack.

For more background information on how these devices relate to network communication, review the OSI model in Appendix A.

Network security best practices for threat prevention

Threat prevention controls aim to reduce the attack surface, limit who or what can reach a given system, and contain the damage of any breach that does occur.

Segment your network

Network segmentation involves dividing a network into logical or functional zones, each one defined as much by who or what is allowed to reach it as by where it sits on the wire. This can be achieved through physical devices such as routers and switches, or virtually via VLANs.

The objective is to contain a security breach within a single zone, limiting disruption and damage. Segmentation also allows IT teams to apply different access rules, security controls, and monitoring levels to each zone based on the sensitivity of the data or systems it contains.

Organizations can set up a demilitarized zone (DMZ) to serve as a buffer between the internal network and the internet or other untrusted networks. The DMZ hosts external-facing services like web application servers.

If an attacker compromises those services, they don’t have direct access to the internal network. An extreme form of segmentation is the air gap, where an organization disconnects systems containing backups or highly sensitive data from the network entirely.

Enforce least privilege and strong authentication

Where security devices sit in the network architecture determines how much protection they deliver. Placement matters as much as configuration. Firewalls should ideally be placed at each network zone junction to serve as barriers between different segments. Modern firewalls often include integrated features like intrusion detection and prevention, DDoS mitigation, and web filtering.

Web application firewalls (WAFs) work best in zones where applications are hosted, such as the DMZ, protecting web applications from SQL injection and cross-site scripting attacks. Load balancers and DNS servers should also be located within the DMZ to optimize traffic flow and reduce the exposure of internal infrastructure.

Require VPNs for remote access

Control physical access to network infrastructure. Only authorized personnel should enter wiring closets, main distribution frames, intermediate distribution frames, server rooms, and data centers. Authentication requirements should apply to all critical physical areas. Organizations should also prohibit the use of USB sticks and external drives to prevent insiders from removing sensitive data.

Position your security devices correctly

Network address translation (NAT) maps private internal addresses to a single public IP address for external communication. NAT masks the internal network structure from outsiders, reducing the network topology information available to potential attackers conducting reconnaissance.

Physically secure network equipment

Personal firewalls are software-based firewalls installed on each computer or server. While often integrated into the operating system, they can also be deployed as third-party applications. Like network firewalls, they restrict incoming and outgoing traffic at the device level. Personal firewalls provide an important layer of protection, even in environments with strong perimeter defenses, particularly for devices connecting from outside the corporate network.

Use network address translation

Application whitelisting creates a list of approved software and allows only those applications to run. This reduces the risk of malware delivered through phishing or malicious websites from executing. Maintaining the approved list requires ongoing effort, since it must be updated as legitimate application needs change across the organization.

Use personal firewalls

A web proxy server authenticates and monitors outbound connections, allowing only traffic initiated by legitimate users. This helps prevent malware within the network from communicating with an attacker's command-and-control server. It also enables security teams to log outbound traffic patterns and identify anomalous communication.

Apply application whitelisting when feasible

Restricting each user's access rights to what is essential for their role limits the damage from accidental or deliberate misuse and reduces the extent to which an attacker can reach with a compromised account. Role-based access control (RBAC) provides a structured approach to assigning permissions based on job function. This reduces the risk of access accumulating or going unreviewed over time and addresses a common insider threat vector.

Strong authentication measures, including multi-factor authentication (MFA), protect credentials even when passwords are stolen. The zero-standing-privilege model takes the least-privilege principle further by eliminating persistent admin accounts entirely, granting elevated access only when needed, and automatically revoking it afterward.

Route internet traffic through a web proxy

A virtual private network (VPN) establishes a secure, encrypted connection over a public network infrastructure, enabling remote users to connect as though they’re directly on the corporate network. VPNs reduce the exposure of internal resources to untrusted networks and encrypt data in transit.

Organizations moving toward remote access security models built on zero trust principles may find that zero trust network access (ZTNA) provides more granular control, verifying each session individually rather than granting broad network access upon connection.

Keep software and firmware patched

Unpatched vulnerabilities in network devices, operating systems, and applications remain among the most exploited weaknesses in enterprise environments. Security teams should maintain a current inventory of all software and firmware versions and apply patches as vendors release them.

A continuous vulnerability management program tracks exposure between patch cycles and prioritizes remediation based on exploitability and business impact. Automated patch management tools reduce the window between vulnerability disclosure and remediation, particularly in high-volume environments where manual patching isn’t practical.

Harden endpoints against malware

Endpoints are common entry points because phishing, drive-by downloads, and credential theft all target devices rather than network infrastructure directly. Endpoint security tools, including endpoint detection and response (EDR) and endpoint protection platform (EPP) solutions, extend visibility into device behavior and block known threats. Applying behavioral monitoring alongside application whitelisting creates multiple detection layers at the device level.

Network security best practices for threat detection and response

Prevention reduces exposure, but detection and response capabilities determine how quickly a team identifies and contains a threat that gets through, especially one already moving under a legitimate but compromised identity.

Baseline network protocols and monitor for deviations

Establish baseline usage patterns for different protocols on wired and wireless networks, and for who normally accesses which systems, from where, and when. Gather data from routers, switches, firewalls, wireless access points, network sniffers, and dedicated data collectors. Monitor for deviations from these baselines, which can indicate data tunneling, malware communicating with external servers, an account accessing systems it's never accessed before, or other threat activity that would otherwise go unnoticed.

Use honeypots and honeynets

A honeypot is a decoy system designed to appear as a real network asset. A honeynet is a network of honeypots that simulates a more complex network environment. Both divert adversaries from production assets and allow security teams to study attack techniques and gather threat intelligence without exposing live systems.

Deploy intrusion detection and prevention systems

An intrusion detection system (IDS) monitors network traffic for potentially malicious activity and alerts administrators. An intrusion prevention system (IPS) goes further, automatically blocking or mitigating threats in addition to generating alerts.

Pairing these tools with SIEM firewall integration enables security teams to correlate alerts across multiple data sources, including identity and access logs, reducing false-positive noise and surfacing real threats more quickly.

By comparing current network activity against established baselines, these tools can detect spikes that may indicate ransomware activity or SQL injection attempts. Attack signature libraries extend detection to known threat patterns.

Automate response to known threats

Many modern security tools can be configured to automatically respond to known threats. For example, these systems can:

• Block the IP address: An IPS or firewall can block the attacking host's IP address. This option is very effective against phishing and denial-of-service attacks. However, some attackers spoof the source IP address during attacks, resulting in the wrong address being blocked.
• Terminate Connections: Routers and firewalls can be configured to terminate connections an intruder maintains to the compromised system by directing TCP RESET packets to the attacker.
• Gain additional insights: Tools can also gather valuable information to determine the initial entry point, which accounts were compromised, how intruders moved around the network, and the data they stole.
• Revoke or suspend access: Identity and privileged access tools can disable a compromised account or revoke standing privileges the moment anomalous behavior is detected, cutting off the path before an attacker can escalate further.

Build and test an incident response plan

Detection without a structured response plan leaves security teams making decisions under pressure, with no defined roles or procedures. An information security policy framework should include a documented incident response plan that assigns roles and responsibilities, establishes communication channels for key stakeholders, and outlines containment steps for known and zero-day threats.

Plans modeled on NIST Cybersecurity Framework guidance provide a recognized structure for each phase of the response lifecycle. The incident response team should rehearse the plan through tabletop exercises before a real incident occurs.

Use solutions from multiple vendors

Using security tools from different vendors reduces the risk from a single point of failure. If one vendor's solution is compromised, other vendors' solutions maintain the defensive posture. A multi-vendor approach also enables greater adaptability as threat landscapes evolve and security requirements change.

Cloud and remote work security

Modern enterprise networks extend well beyond the corporate perimeter. Remote workers, cloud workloads, and SaaS applications mean that network security controls must follow users and data wherever they operate.

Cloud security policies should address access management for cloud-hosted resources, encryption of data in transit and at rest, and monitoring of cloud service provider environments. Shared responsibility models mean that cloud providers secure the underlying infrastructure, but organizations remain responsible for securing what runs on top of it.

For remote workers, VPNs and ZTNA solutions extend secure access to off-network devices. Organizations should apply the same data loss prevention controls to remote endpoints as they do to on-premises devices and maintain visibility into the data that remote users access and transfer.

How Netwrix helps you monitor and secure your network

Netwrix answers the question this piece keeps coming back to: who and what can reach your network, and what happens once they're in.

Netwrix Auditor delivers continuous visibility into user activity, configuration changes, and access events across hybrid Microsoft environments. That's the record that catches an account reaching for something it's never touched before, so teams can investigate before it becomes an incident.

Netwrix Privilege Secure, mirroring the "revoke or suspend access" response described above, but built in rather than bolted on.

Request a demo to see how Netwrix can help you monitor network activity, enforce least privilege, and detect threats before they escalate.

Appendix A: The OSI Model

The OSI (Open Systems Interconnection) model is an established framework for network systems. It comprises seven layers, from physical hardware to application-level interactions: