Intrusion Detection Systems (IDS) Explained

Key Concepts

Intrusion Detection Systems (IDS) are security tools designed to monitor and analyze network traffic and system activities for signs of potential security breaches. IDS can be classified into two main types: Network-based IDS (NIDS) and Host-based IDS (HIDS).

Network-based IDS (NIDS)

A Network-based IDS (NIDS) monitors network traffic for suspicious activities. It analyzes packets passing through the network and compares them against a database of known attack patterns. If a match is found, the NIDS generates an alert.

Example: Imagine a security camera installed at the entrance of a building. The camera continuously records and monitors everyone entering and leaving. If it detects someone behaving suspiciously, it alerts the security personnel.

Host-based IDS (HIDS)

A Host-based IDS (HIDS) monitors the activities on individual hosts or servers. It checks for unauthorized changes to files, logs, and system configurations. HIDS can detect intrusions that may not be visible at the network level.

Example: Consider a security guard stationed inside a building. The guard checks each room for any unauthorized activities, such as tampering with files or changes in the environment. If anything suspicious is found, the guard reports it immediately.

Types of IDS Alerts

IDS can generate different types of alerts based on the severity and nature of the detected activity:

• False Positive: An alert that incorrectly identifies a benign activity as malicious.
• False Negative: An alert that fails to detect a real attack.
• True Positive: An alert that correctly identifies a malicious activity.
• True Negative: An alert that correctly identifies a benign activity as non-malicious.

Example: Think of a security alarm system in a house. A false positive would be the alarm going off when there is no intruder, while a false negative would be the alarm failing to go off when there is an intruder. A true positive is the alarm correctly detecting an intruder, and a true negative is the alarm correctly not going off when there is no intruder.

Importance of IDS

IDS plays a crucial role in enhancing an organization's security posture by providing early detection of potential threats. It helps in:

• Real-time Monitoring: Continuous monitoring of network and host activities.
• Threat Identification: Identifying known and unknown threats.
• Incident Response: Facilitating quick response to security incidents.
• Compliance: Ensuring compliance with security policies and regulations.

Example: Imagine a city with a robust security system that includes cameras, patrols, and alarms. This system helps in monitoring the city 24/7, identifying suspicious activities, responding to emergencies quickly, and ensuring that the city complies with safety regulations.