Network Audit: A Practical Guide for Industrial IT and OT Environments

A network audit helps organisations understand what is connected, how systems communicate and where risks may exist. In industrial environments, this is especially important because networks often support production lines, control systems, remote access, data collection and safety-critical operations.

A structured network audit gives IT and OT teams a clearer view of assets, configurations, traffic flows, access rights and potential weaknesses. It also supports better planning before upgrades, cybersecurity projects or new industrial connectivity work begins.

What Is a Network Audit?

A network audit is a detailed review of network infrastructure, devices, connections and controls. It can include switches, firewalls, routers, servers, workstations, PLCs, HMIs, industrial gateways, wireless links and remote access routes.

The aim is not simply to produce a list of equipment. A good audit shows how assets are connected, which systems communicate, whether configurations are documented and where operational or security risks may affect performance.

For industrial organisations, the review should consider both IT and OT requirements. Availability, safety, legacy systems and vendor access often matter as much as traditional security controls.

Network Audit Checklist for Industrial Sites

A practical network audit should start with clear scope. Define the sites, systems, zones and assets included. Confirm whether the review covers office IT, production OT, remote access, wireless infrastructure, cloud connections or all of these areas.

Key steps include:

• Build an asset inventory of known and unknown devices
• Review network diagrams, IP addressing and segmentation
• Check firewall rules, routing and switch configurations
• Review user access, privileged accounts and remote connections
• Identify unsupported devices, outdated firmware and weak configurations
• Document data flows between OT, IT and external systems
• Assess backup, change control and incident response processes

Where production systems rely on industrial protocols, the audit should also consider how data moves between control systems and business applications. Solutions such as OPC software and middleware can support structured data exchange when requirements are clear.

Network Audit for OT Cyber Security

An OT network audit should identify risks without disrupting operations. Many industrial systems run continuously, so scanning, testing and documentation must be planned carefully.

This is where OT knowledge is important. A standard IT review may miss issues linked to legacy PLCs, unmanaged switches, flat networks, shared accounts or unsupported engineering workstations. It may also underestimate the impact of downtime.

The findings can support wider OT cyber security work by providing evidence for risk assessments, segmentation plans and security improvement roadmaps. They can also help organisations decide where tools such as industrial firewalls, asset monitoring or controlled remote access are needed.

What To Review During an Industrial Network Assessment

A useful review looks beyond hardware. It should consider policies, procedures and responsibilities as well as technical settings. Asset visibility is the foundation. Teams need to know which devices are active, where they are located and who owns them. This can include production equipment, engineering laptops, HMIs, servers, wireless bridges and external vendor connections.

Access control is equally important. Review who can connect, how permissions are granted, whether accounts are shared and how access is removed when no longer required. For OT environments, this should include maintenance teams, OEMs and third-party suppliers.

Resilience should also be checked. A network audit can highlight single points of failure, poor documentation, missing backups and limited recovery procedures. Products such as AMDT Octoplant can help with version control and backup management where configuration integrity is a concern.

 

Network Audit Findings and Next Steps

The output of a network audit should be practical. A long list of findings is only useful if it helps teams act. Findings should be grouped by priority, operational impact and effort required.

Typical recommendations may include improving segmentation, removing unused rules, documenting assets, limiting remote access, replacing unsupported devices or reviewing backup procedures. Where remote assets or industrial communication devices are involved, machine communications solutions may also be relevant.

For higher-risk environments, the review may lead into more detailed industrial cyber security services, including assessment, network design, diagnostics, implementation and compliance support.

We also offer a network audit service to help industrial organisations assess the current state of their IT, OT and industrial network environments. This can include reviewing connected assets, topology, segmentation, remote access routes, switch and firewall configuration, and potential areas of risk. The findings provide a practical baseline for improving resilience, prioritising OT cyber security actions and supporting safer long-term network planning.

How Often Should a Network Audit Be Completed?

There is no single timetable that suits every organisation. However, a network audit should be reviewed after major changes, site expansions, new machinery installations, remote access changes or cybersecurity incidents.

Many industrial organisations benefit from a regular review cycle. This helps maintain accurate documentation, improve visibility and reduce the risk of unmanaged change. It also supports compliance, supplier management and long-term operational resilience.

Practical Value for Industrial Teams

The main value is clarity. When teams can see assets, connections and risks, they can make better decisions about maintenance, upgrades and security investment. This is especially useful in environments where production equipment has been added over many years and documentation has not kept pace.

A good review also improves communication between engineering, IT, OT and management teams. It creates a shared view of current conditions and helps prioritise work based on business impact rather than assumptions.

It also gives suppliers clearer context before recommending products or support. Instead of working from assumptions, they can review known constraints, critical assets and operational priorities. This helps reduce misconfiguration, avoids unnecessary changes and supports a more controlled improvement plan across industrial sites and connected systems safely over time.