Network equipment analysis: auditing, traffic, and security

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A company's network has become the nervous system of the entire businessIf it fails, production stops, access to critical applications is cut off, and the risk of a serious security incident, such as the following, increases significantly: cyberattacks in SpainHaving the equipment turned on and "browsing" is no longer enough; it is necessary to know what is really happening through the cables and Wi-Fi, who is connecting, how the infrastructure is performing, and what doors are open to potential attackers.

A good network equipment analysis combines auditing, monitoring, and security review. to answer key questions: Is the network correctly sized? Are there outdated devices slowing down performance? Are there security gaps? computer viruses Or poorly implemented protocols? What traffic enters and leaves the Internet, and to what destinations? Throughout this article, we will break down, in great detail, how this analysis is approached and what tools and techniques are used in both corporate and industrial environments.

Why is it so important to analyze and audit the network

Network audits allow you to know the "health status" of the infrastructure and anticipate problems before they cause a widespread outage or a security breach. These analyses can detect misconfigurations, performance bottlenecks, unsupported equipment, vulnerabilities, internal and external threats, or even malformed frames that can destabilize end systems.

In corporate networks, the usual focus is on internet access.Because it is usually the most heavily loaded and critical link in the entire organization, poor bandwidth management or an external attack can leave the entire workforce without service. In industrial networks, however, the challenge is different: the number of proprietary or poorly documented protocols often necessitates the use of specialized analyzers capable of understanding each frame and validating its implementation.

Beyond solving specific problemsOrganizations turn to network analysis and auditing when they need to take stock of what they actually have deployed, prepare for a major infrastructure upgrade, meet regulatory requirements (e.g., PCI DSS in the financial sector), or simply ensure that the network remains aligned with current business needs.

These audits are not limited to securityThey also review availability, performance, service quality, monitoring processes, access controls and administration, so that a formal report can be issued with vulnerabilities, risks and clear recommendations for management and the technical team.

Complete audit of network and IT infrastructure

The first part of the analysis involves a thorough review of the entire IT infrastructure.: servers (including how set up a home serverThis includes switches, routers, firewalls, wireless access points, power systems, structured cabling, end devices, and, in industrial environments, control and automation equipment. The goal is to verify that all hardware is properly documented, supported by the manufacturer, and in optimal operating condition.

In this phase, a very detailed inventory is usually compiled. This database records models, firmware versions, device capabilities, available interfaces, installed modules, compatibility with management protocols (SNMP, NetFlow, sFlow, etc.), and lifecycle milestone dates (end of sale, end of support, end of life). This work can be done manually or with specific auditing tools that automate much of the discovery process.

IT infrastructure audits don't stop at just the physical inventoryThey also evaluate how well internal controls, network segregation, high availability mechanisms, configuration standardization, and IT governance are designed. The idea is to verify whether best practices are actually being followed or if "patches" have accumulated over time.

A well-planned infrastructure assessment helps to better size and protect the networkIt improves scalability, increases stability, reduces downtime, and leverages existing technology more effectively. This includes, among other features, proactive and incremental monitoring, preventative mechanisms for high availability, resource optimization and consolidation, and enhanced operational visibility.

In parallel, IT assurance services focus on protecting information Relying on the five pillars of security: integrity, availability, authentication, confidentiality, and non-repudiation. This involves internal and external infrastructure audits, certification services, business resilience analysis, and reviews of privacy and data protection policies.

The server and communications room: the physical heart of the network

The server and communications room houses the critical elements of the networkPhysical servers, perimeter firewalls, main routers, core switches, patch panels, and, in many cases, storage and virtualization equipment. Any serious analysis of network equipment must dedicate specific attention to this area.

Physical aspects are just as important as logical ones.The ambient temperature, cleanliness and dust accumulation on the equipment, the correct organization of the cabling within the racks, the labeling of ports and cables, the adequate separation between power supply and data, as well as physical access to the room (control of keys, cards, cameras, entry and exit records) are checked.

The router that provides the main internet connection deserves a detailed analysisIt is verified that the connection offered by the provider is stable, secure, with sufficient capacity, that the hardware has Gigabit Ethernet ports or higher, that it supports the necessary monitoring protocols, and that the quality of service and bandwidth control policies are well defined.

The condition of the cabling entering and leaving the room is also checked.ensuring that the category (5e, 6 or higher) is consistent with the required speeds, that the terminations on RJ45 panels and sockets are correct, and that there are no splices or "makeshift" connections that could limit the transfer capacity or generate link errors.

Finally, auxiliary systems such as UPSs, air conditioning and sensors are reviewed.A properly sized UPS allows servers and communications to remain active long enough to perform organized backups and shut down equipment without risk of data corruption. Cooling and environmental monitoring are key to extending hardware lifespan and preventing unexpected downtime.

Switching, access and cabling equipment

Switches are responsible for distributing traffic intelligently among all devices connected via Ethernet. During the analysis, it is evaluated whether their switching capacity, the number of ports and their speed (Fast Ethernet, Gigabit, 10 GbE) are sufficient for the current and future load, and whether any obsolete electronics are limiting the overall performance of the network.

It's relatively common to find old switches. These devices, which don't reach 1000 Mbps, act as bottlenecks at key points, hindering communication between servers, storage, and workstations. Detecting and replacing these devices has an immediate impact on the performance perceived by users.

Wireless access points (APs) are also an essential part of the analysisTheir location is checked to ensure homogeneous coverage, it is verified that they are connected to network sockets capable of supporting the necessary bandwidth, that they have adequate power (PoE when applicable) and that their security configuration (WPA2/WPA3, VLANs, client isolation) is correct.

The type and quality of structured cabling has a huge impact on performanceIt is recommended to use at least Category 5e or 6 cabling, or higher, in new installations to reliably support Gigabit speeds or even 10 Gigabit speeds over short distances. In addition to the category, connectors, wall plates, patch cords, and proper placement in cable trays and conduits are checked.

Connectivity and electrical protection are specifically checked at the server location.Accessible location, Gigabit or higher connection to the network core, connection to redundant UPSs, and adequate cooling to prevent overheating. All of these factors directly impact the stability of the services consumed by users.

Analysis of connected devices and network security

One of the key objectives of network equipment analysis is to know who is connectedThrough network scans, SNMP queries, review of ARP and MAC tables and discovery tools, all present devices are identified: PCs, servers, printers, IP cameras, IoT devices, industrial equipment, mobiles, etc., and it is checked whether they are authorized.

Controlling which devices access the network is essential to minimizing risksThe existence of "phantom" or uninventoried equipment is often the gateway to security breaches. In industrial networks, hardware analyzers can even validate that devices correctly implement protocols such as Modbus or DNP3, preventing unexpected behavior.

The network security review encompasses several layersThe logical scheme is analyzed (segmentation into VLANs, demilitarized zones, guest networks), firewall policies and access control lists are reviewed, passwords and authentication methods are audited, and antimalware solutions, IDS/IPS and backup systems are verified.

At this point, vulnerability assessment becomes important.Based on the inventory and collected data, the auditors attempt to "attack" the network first from the outside (simulating an external attacker) and then from the inside (assuming an internal device is compromised). The goal is to chain together small weaknesses until they achieve high-level access and demonstrate the true impact.

After exploiting vulnerabilities, a manual verification is always performed. to separate false positives from real problems, identify systemic causes, and prioritize mitigation actions. The findings are compiled in a management report, accompanied by technical and business recommendations: replacement of obsolete equipment, configuration changes, policy tightening, staff training, etc.

Network analysis tools: software and hardware

There are two main families of tools for analyzing network traffic and equipment behavior.: software-based solutions, usually generic and capable of interpreting widely documented protocols, and hardware solutions, more geared towards specific environments (especially industrial) and with support for very specific protocols.

The most well-known software network analyzers are Wireshark, TCPDump, and Windump.Wireshark, for example, captures frames in real time and allows you to dissect them layer by layer, showing source and destination addresses, ports, protocol flags, and application content. It is useful both for diagnosing errors and for studying whether packets meet specifications.

In the area of ​​network inventory and mapping Tools such as SolarWinds, Open-AudIT, and NetformX are used, capable of discovering devices, generating topology diagrams, associating relationships between devices, and creating comprehensive reports. Other solutions like Nessus and Nipper focus on security assessment, reviewing configurations, proposing best practices, and detecting vulnerabilities such as... hidden cyberattack in browsers.

For performance evaluation and detailed traffic analysisIn addition to Wireshark, utilities such as iperf, ntop, or NetFlow/sFlow flow analysis systems are used, which help to understand who consumes the most bandwidth, which applications generate the most traffic, and how the load varies over time.

Hardware analyzers, very common in industrial control systemsThey typically include advanced features such as a fuzzer for testing protocol implementations, an oscilloscope for checking signals and frequencies, and electrical panel analyzers. Products like Achilles, Netdecoder, or Line Eye devices are specifically designed to work with Ethernet, serial (RS-232, RS-485), fiber, and other media interfaces.

Methods for capturing and analyzing network traffic

In order for a software analyzer to be able to study network trafficIt is necessary that the frames of interest reach the equipment where it is installed. This can be achieved in several ways: by connecting an old hub where all traffic is repeated across all ports, by configuring a mirrored port (SPAN) on a switch, or by using specific hardware devices such as Network TAPs.

Using a mirrored port on a switch is the most common option in modern networksThe switch is instructed to copy all traffic from one or more ports or VLANs to a designated port, to which the analyzer is connected. This allows for accurate monitoring of what passes through the switch, although it's important to note that excessive traffic can saturate the mirrored port and cause missed captures.

Network TAPs are devices designed to insert a “transparent” observation point. between two network segments. They replicate traffic to the analyzer without interfering with communication, and typically support different physical media and speeds. In industrial or mission-critical environments, where switching configurations are undesirable, they are a highly valued option.

The big difference between software and hardware analyzers The former focus primarily on monitoring and analyzing captures (even after the fact), while the latter add active protocol testing capabilities, physical signal measurement, and synthetic traffic generation, which is vital for validating industrial equipment without relying on public manufacturer documentation.

In any case, the use of analyzers must be planned. To avoid impacting production: protocol implementation tests or fuzzing campaigns should be run in laboratory environments or when the main system is not in use, as they generate invalid packets that can leave the network or controllers in unstable states.

Protocols and techniques for discovering equipment and topology

A key part of network equipment analysis is automatically discovering the topology and the relationships between devices. This is achieved by combining various protocols and techniques, which allow management tools to jump from device to device until the complete network map is drawn.

SNMP is the most widespread network management protocolCompatible devices (routers, switches, firewalls, printers, etc.) include an SNMP agent that responds to manager queries via UDP, avoiding the overhead of a TCP connection. Managed information is organized into object identifiers (OIDs) within MIB databases, which store counters, interface states, forwarding tables, ink levels, port statistics, and much more.

The LLDP (Link Layer Discovery Protocol) protocol provides another piece of fundamental informationEach device that supports it periodically advertises data about itself (device type, identifier, port) to its direct neighbors at layer 2. These neighbors store this data in their own MIBs, so that management tools can chain neighbors together to reconstruct the physical topology.

Even simple utilities like ping are still useful for discovery.By sending ICMP echo requests and checking who responds, it's possible to detect active devices on a subnet. This technique is simple, but when combined with SNMP, ARP, and other methods, it helps to complete the inventory.

The ARP protocol, responsible for associating IP addresses with MAC addressesThis is also leveraged during audits. By querying the ARP cache of routers and switches via SNMP, management software can build its own database of routes, subnets, and Layer 2 and Layer 3 neighbors, continuing this recursive process until all known segments are covered.

Network traffic analysis, NetFlow, and advanced visibility

In addition to capturing individual packets, many organizations rely on flow analysis. to obtain an aggregated view of traffic. Technologies such as NetFlow (Cisco), sFlow, J-Flow or IPFIX export summaries of network conversations to a central collector, which stores and graphically represents them.

Tools like NetFlow Analyzer are responsible for collecting that flow data.They correlate this data and generate reports with information on who is consuming bandwidth, which applications are generating the most traffic, which ports and protocols are being used, and how network usage has evolved over different periods. They allow you to view both real-time data (one-minute granularity) and historical data for hours, days, months, or quarters.

These traffic analysis systems usually offer very comprehensive dashboardswhere you can identify at a glance which interface, application, user, host, or conversation is hogging resources. Reports are typically exported in CSV or PDF format, which is especially useful for presenting to senior management and justifying investments or policy changes.

Another interesting point is the ability to detect anomalous behavior. through the traffic flows themselves: unusual spikes in traffic to specific ports, patterns reminiscent of denial-of-service attacks, flows with strange TOS values, or malformed packets. By classifying these events, internal or external threats can be identified, allowing for a rapid response.

Traffic analyzers are also becoming a key forensic tool in the event of a possible intrusion. By preserving detailed information about what has happened on the network, they allow the incident to be reconstructed: which equipment was involved, what volumes of data were exfiltrated, and at what times the suspicious accesses occurred.

How to structure and execute a network audit step by step

Any robust network security audit or assessment relies on three main phasesPlanning, execution, and post-audit. Skipping or minimizing the planning stage usually ends in frustration and wasted time, because permissions, data, or tools are discovered missing halfway through the project.

During the planning phase, the scope is precisely defined.: what devices are included (usually routers, switches, firewalls and security equipment, leaving out workstations and application servers unless otherwise stated), what objectives are pursued (inventory, compliance, troubleshooting, performance improvement), what regulations apply and what work windows will be used.

The commitment of stakeholders is also ensuredWithout support from management and the technical team, it is virtually impossible to perform a complete network audit, as it requires access credentials (SNMP, Telnet, SSH), temporary configuration changes (such as enabling SNMP or SPAN), and even computers or laptops with sufficient capacity to run the necessary tools.

Tool selection is another key point in this phaseFor small networks, a more manual approach can be chosen, connecting device by device, but in medium and large environments it is usually essential to use automatic discovery solutions, configuration analysis, vulnerability scanners and traffic analyzers.

Once the plan has been drawn up, the audit execution begins.With the credentials prepared and the tool configured (SNMP community strings, Telnet/SSH usernames and passwords, IP ranges, or seed devices), the discovery process begins. Depending on the size of the network, this phase can last from a few hours to several days.

Once the data collection is complete, the post-audit stage begins.where all results are analyzed in depth: reports are generated, risks are identified, vulnerabilities are prioritized by impact, false positives are separated, and clear recommendations are drafted. Part of the report will focus on business language (costs of an outage, legal risks, impact on productivity) and another part will be purely technical.

Detailed phases in network security assessments

In more thorough security audits Specialists usually divide the work into several well-differentiated technical phases to ensure that no angle is left unchecked.

The first phase is footprint analysis and information gatheringHere, a physical and virtual inventory of the network is created: hardware, software, licenses, domain names, IP ranges, published services, routes, security policies, monitoring processes already in operation, etc. The goal is to have the most complete network model and security profile possible.

The second phase focuses on the analysis and evaluation of vulnerabilities from an external perspectiveTaking advantage of the information gathered, the aim is to penetrate the network by exploiting low-level weaknesses that, together, can provide access to sensitive information or critical systems.

The third phase repeats the same strategy, but from within the organization.The scenario assumes an attacker has already gained entry (for example, via a phishing email or an infected USB drive) and attempts to escalate privileges and move laterally. This tests the strength of internal defenses and system segmentation.

In the fourth phase, each exploited vulnerability is manually verified.This involves reviewing configurations, versions, patches, and potential alternative attack vectors. This verification prevents resources from being invested in remediating problems that are not truly exploitable or that have minimal impact on the organization's specific context.

Finally, a comprehensive vulnerability analysis is performed. to identify patterns and root causes: design errors, lack of policies, lack of training, unsupported equipment, absence of regular testing, etc. From there, prioritized action plans are defined, which the IT department must implement in coordination with management.

Both network audits and IT infrastructure audits are essential to ensure that the company's computer systems are robust, can be used with confidence, and offer the highest possible level of privacy and protection against increasingly sophisticated cyber threats.

A rigorous analysis of network equipment, combined with continuous monitoring, good tools, and regular reviews It makes the difference between an organization that reacts to problems when it is too late and one that detects failures, attacks and bottlenecks in time, avoiding business interruptions, data loss and penalties for regulatory non-compliance.