Cyberattacks no longer target only large corporations or governments. Small businesses, healthcare providers, and educational institutions now face daily attempts to breach their networks.
According to IBM’s Cost of a Data Breach Report, the global average cost of a data breach reached USD 4.45 million, reflecting a steady rise year over year. Against this backdrop, organisations require mechanisms that do more than just block traffic. They must observe, analyse, and detect malicious activity in real time. An Intrusion Detection System (IDS) plays a central role in meeting this requirement.
Understanding the Basics of an Intrusion Detection System
An Intrusion Detection System is a security tool that monitors network traffic or system activities to identify suspicious behaviour, policy violations, or potential attacks.
Unlike preventive tools that actively stop threats, an IDS focuses on detection and alerting. It acts as a surveillance system, constantly watching for indicators of compromise.
IDS solutions compare observed activity against known attack patterns or normal behaviour baselines. When deviations occur, the system generates alerts for security teams to investigate. This early warning capability helps organisations respond before attackers cause extensive damage.
Why Intrusion Detection Systems Are Necessary
Modern networks handle vast volumes of data and support remote work, cloud services, and third-party integrations. Firewalls alone cannot inspect every internal action or lateral movement. Industry data shows that over 60% of breaches involve compromised credentials or insider misuse, which traditional perimeter defences often miss.
An IDS addresses this gap by monitoring internal and external activity. It detects reconnaissance attempts, malware communication, brute-force logins, and policy violations. How can organisations protect sensitive data if they remain blind to what happens inside their own networks? IDS provides that visibility.
Types of Intrusion Detection Systems
Network Intrusion Detection System
Network Intrusion Detection System (IDS) monitors the network traffic and can detect different attacks such as viruses, worms, Trojans, buffer overflow, denial of service attacks, etc. A Network Intrusion Detection System (IDS) provides all the necessary features and functions to detect intrusions.
NIDS can be deployed in various forms, such as host-based, network-based, or cloud-based, depending on an organisation’s requirements. The main advantage of using NIDS is that it can detect both known and unknown attacks through signature detection and anomaly detection techniques. Once an attack is detected, the system sends alerts to administrators with details about the attack so they can take appropriate measures to prevent further damage.
Network intrusion detection systems are used for different network applications such as network monitoring, web applications, intrusion detection, enterprise security, firewall, network security, etc.
Host Intrusion Detection System
A Host Intrusion Detection System (HIDS) is a crucial security measure that can safeguard your system against unauthorized access, misuse, and abuse. HIDS monitors the activity on individual systems such as servers or workstations and identifies any suspicious behaviour. This system helps in detecting and preventing known and unknown attacks before they cause significant damage to your system.
A HIDS works by monitoring the file configurations, registry settings, logs, network activity, and other critical aspects of a host machine. The system evaluates this information against predefined security policies to identify any unusual or malicious activity. In case of an attack, HIDS alerts the administrator immediately so that quick action can be taken to prevent further damage.
Without a proper intrusion detection system in place, attackers can quickly exploit vulnerabilities in your network by installing malware or accessing sensitive data without authorisation. A HIDS ensures that all endpoints are monitored round-the-clock for potential threats.
Intrusion Prevention System
An Intrusion Prevention System (IPS) is a proactive security measure designed to prevent unauthorised access to computer networks. IPS technology works by examining network traffic in real-time, identifying potential threats, and taking action to block them before they can cause harm. An IPS is an essential component of any comprehensive cybersecurity strategy.
Intrusion Prevention Systems are capable of detecting and preventing a wide range of cyber attacks, including malware infections, denial-of-service attacks, and SQL injection attempts. By analysing network traffic patterns and comparing them against established baselines, an IPS can quickly identify suspicious activity and take steps to mitigate the risk. This makes it an invaluable tool for businesses seeking to protect their sensitive data from would-be attackers.
One key advantage of Intrusion Prevention Systems is that they are able to act autonomously without requiring human intervention.
Protocol-based intrusion detection system (PIDS)
A PIDS operates by analyzing network traffic using predefined protocols to identify suspicious activity. It can detect anomalous behaviour such as network scans, port scanning, or attempts at unauthorized access. Additionally, it can provide alerts and notifications to IT professionals when an attack is detected, allowing for prompt mitigation before any significant damage occurs.
With the increasing sophistication of cyber attacks, it’s essential to have a robust security infrastructure in place. A PIDS provides an extra layer of protection against malicious activity that may go undetected by traditional firewalls or antivirus software.
Purpose of Using an Intrusion Detection System
The main goal of an intrusion detection system is to detect security threats by monitoring traffic and activity on a system. Software-based intrusion detection systems can be installed on each workstation or on the network gateway. If installed on the network gateway, remote users can access the IDS to report suspicious activity.
An Intrusion Detection System (IDS) identifies the intrusion attempts made in the network, whether in the form of viruses, worms, Trojans, back doors, application attacks, buffer overflow or Denial of Service (DoS). Identifying the intrusions is done by checking the packets, identifying the network traffic, collecting the logs and analysing the data based on the predefined rules.
Intrusion detection systems should be considered as a layer of security on top of the underlying operating systems, network, and services, and not in place of these layers. An IDS should only be installed if there is a clear need to monitor that area of the network.
Conclusion
An IDS (Intrusion Detection System) can be described as a device or software system that monitors the activities of an IT network and produces events that indicate that the network has been compromised. The IDS can alert the network administrator about the issue and take corrective action. This may include sending a ‘message’ to notify the system administrator, alerting the system administrator or notifying the users who are connected to the network.
