IDS vs. IPS: Key Difference and Similarities

An intrusion detection system (IDS) is defined as a solution that monitors network events and analyzes them to detect security incidents and imminent threats. An intrusion prevention system (IPS) is defined as a solution that performs intrusion detection and then goes one step ahead and prevents any detected threats. This article lists the key differences and similarities between IDS and IPS.

What Is an Intrusion Detection System (IDS)?

Intrusion detection systems (IDS) monitor enterprise networks and analyze events to detect security incidents and imminent threats. These security solutions protect businesses by proactively thwarting potential cybersecurity incidents.

IDS/IPS on an Enterprise Network

An intrusion detection system is a monitoring solution that spots suspicious network incidents and sends out alerts to incident responders or security operations center (SOC) analysts. These alerts enable security personnel to investigate the detected issues and execute the appropriate countermeasures to address them before significant damage occurs.

Two main network deployment locations exist for IDS—host-based IDS (HIDS) and network-based IDS (NIDS). HIDS is deployed at the endpoint level and protects individual endpoints from threats, while NIDS solutions monitor and protect entire enterprise networks.

Apart from its deployment location, IDS also differs in terms of the methodology used for identifying potential intrusions. Signature-based IDS leverages fingerprinting to identify known threats, such as malware. Once malicious traffic is identified, its signature is captured and added to the database. Each signature in this database is compared against network traffic in real time to detect new threats. This type of IDS is capable of detecting known threats rapidly and accurately.

False positives are extremely rare as alerts are only sent out once a known threat is detected. However, signature-based IDS solutions cannot detect unknown threats and would be helpless in the face of zero-day vulnerabilities.

On the other hand, anomaly-based IDS operates by creating a ‘normal’ network behavior model. All future network activity is compared against this behavior model, and network anomalies are highlighted as potential threats, with alerts being sent out to security personnel. This type of IDS is capable of detecting zero-day threats. However, both false positives and false negatives are possible here.

Finally, hybrid IDS uses signature-based and anomaly-based threat detection to detect cyberattacks with precision and speed.

What Is an Intrusion Prevention System (IPS)?

Intrusion prevention systems (IPS) perform intrusion detection and then go one step ahead and stop any detected threats. 

An intrusion prevention system is a network security hardware or software that continuously observes network behavior for threats, just like an intrusion detection system. However, IPS goes one step ahead of IDS and automatically takes the appropriate action to thwart the detected threats, including measures such as reporting, blocking traffic from a particular source, dropping packets, or resetting the connection. Some IPS solutions can also be configured to use a ‘honeypot’ (a decoy that contains dummy data) to misdirect attackers and divert them from their original targets that contain accurate data.

IPS is a critical component of modern-day enterprise security. This is because the organizational networks of 2022 have numerous access points and process high data volumes, thus making manually monitoring traffic and responding to threats an imposing task. Additionally, the increased popularity of cloud platforms means enterprises are operating in highly connected environments. While this has various benefits, it presents a vast attack surface and increases vulnerability if the cloud platform is not adequately secured.

As the threats faced by enterprise systems grow in number and become more sophisticated, automated security solutions such as IPS have become more vital than ever before. This network security solution allows businesses to counter threats in near real-time without stretching security teams’ capabilities. It does so by scanning high volumes of traffic without hampering network performance. Many security providers club IPS with unified threat management (UTM) or next-generation firewall (NGFW) solutions.

IPS solutions are placed within flowing network traffic, between the point of origin and the destination. IPS might use any one of the multiple available techniques to identify threats. For instance, signature-based IPS compares network activity against the signatures of previously detected threats. While this method can easily deflect previously spotted attacks, it’s often unable to recognize newly emerged threats.

Conversely, anomaly-based IPS monitors abnormal activity by creating a baseline standard for network behavior and comparing traffic against it in real-time. While this method is more effective at detecting unknown threats than signature-based IPS, it produces both false positives and false negatives. Cutting-edge IPS are infused with artificial intelligence (AI) and machine learning (ML) to improve their anomaly-based monitoring capabilities and reduce false alerts.

Finally, policy-based IPS relies on security policies set by the enterprise to detect and block violations. This type of IPS is less common than signature-based and anomaly-based measures as it requires security teams to create and set up relevant policies manually.

See More: What Is Real User Monitoring? Definition, Key Components, and Best Practices

Top 5 Similarities Between IDS and IPS

Intrusion detection systems and intrusion prevention systems both work to protect network infrastructure. They mainly detect threats by comparing network traffic against a database of known cyber attack signatures or a ‘normal’ network behavior model. The main difference between IDS and IPS is that, while the former simply ‘monitors’ network traffic, the latter ‘controls’ it.

A significant overlap exists in the way IDS and IPS operate. Listed below are the top five similarities between the two cybersecurity solutions.

Similarities Between IDS and IPS

1. Built for modern enterprises

The rising prevalence of remote work in the post-pandemic corporate landscape has led to enterprise networks dealing with more access points and higher traffic volumes than in the past. As such, manual network monitoring has become extremely difficult, especially in highly connected cloud environments. In addition to this, the cyber threats faced by enterprise security teams are increasing in number and sophistication.

All this makes cutting-edge IDS and IPS solutions a vital part of the cybersecurity systems of any modern organization. These automated security tools allow organizations to respond to attacks swiftly and efficiently. Regular updates also help these systems stay updated regarding the latest security threats.

2. Operate using signature databases or behavior models

IDS and IPS secure enterprise systems using either a signature-based or a behavior modeling-based approach. Some cybersecurity solutions may even adopt a hybrid methodology that combines the two approaches. Once a threat is detected, these cybersecurity systems alert IT personnel and can even initiate automated actions. 

Signature-based intrusion detection and prevention systems are best suited for identifying known cyber threats. These solutions compare network data against a predetermined list of known indicators of compromise.

An indicator of compromise is defined as any specific behavior known to precede a malicious attack. It includes known byte sequences, malicious domains, file hashes, and even suspicious email content, such as subject lines. Once an indicator of compromise is detected, the packet is flagged for further action.

Upon capturing a signature match, the intrusion detection or intrusion prevention system highlights it and takes further action. Such systems are nearly immune to false positives and negatives and detect threats with very high speed and efficiency. However, they cannot detect a threat if its signature is not present in their databases.

Conversely, behavior model-based intrusion detection and intrusion prevention systems work by detecting anomalies and initiating action in case of unknown or suspicious behavior. Rather than exclusively searching for known threats, these detection and prevention systems use machine learning to build a ‘normalized’ point of reference for how the network behaves typically. All network activity is continuously compared against this baseline. These systems do not search for known indicators of compromise. Instead, they work by identifying anomalous behavior.

IDS and IPS that operate on the behavior analysis principle act on any network behavior that fails to align with the created behavior model. For instance, these systems will highlight user activity outside of business hours, the addition of new devices to a network, or multiple previously-unknown IP addresses attempting to connect with the network.

This might lead to non-malicious behaviors being highlighted simply for being abnormal. Such false positives could require the allocation of additional resources for investigation. However, IDS and IPS that use behavior-based anomaly detection can detect new threats that signature-based detection and prevention systems cannot.

3. Leverage automation

Unlike traditional cybersecurity measures that require round-the-clock monitoring by security personnel, IDS and IPS use automation to protect highly digitalized enterprise environments. This helps IT teams secure organizational networks from cyber threats while expending minimal resources.

Intrusion detection and prevention systems offer network protection using either a hardware-based or a software-based approach. In the former, sensors are strategically placed at key points on the enterprise network to monitor network data. In the latter, detection and prevention tools are installed on devices linked to the network to track inbound and outbound data. Once a threat is detected, these solutions automatically raise the alarm. Based on configured rules and policies, IPS can also initiate further actions without human intervention.

4. Make compliance hassle-free

Regulators in many jurisdictions require corporations to ensure the security of customer data. This is especially true for enterprises operating in more sensitive industry verticals such as healthcare and finance. Complying with the laid down directives entails investments in industry-standard data protection measures, such as IDS and IPS. These security solutions help ensure compliance by addressing numerous regulatory requirements. Additionally, they maintain auditing records that are useful during compliance investigations.

With enterprises constantly increasing their digital footprint, monitoring the complete network environment requires more resources than they normally have. IDS and IPS spot and stop malicious data before it can cause major damage. Through the automated implementation of compliance requirements, IDS, IPS, and other security devices work in unison to reduce the pressure on human security teams.

Complying with stringent regulatory directives might also require the in-depth monitoring of business infrastructure. IDS and IPS can passively monitor various network segments and control less visible traffic. For instance, if installed correctly, these solutions can highlight anomalies in traffic that exist only within a LAN connection and are unmonitored by other security solutions.

Setting IDS and IPS alerts also enables robust protection in line with compliance requirements. Real-time monitoring by intrusion detection and prevention systems allows IT personnel to take the required actions as soon as an anomaly is detected. This helps prevent violations by significantly reducing the complexity of the enterprise’s decision-making process.

Finally, in case of a security breach, the data collected by IDS and IPS may be admissible in the courts of certain jurisdictions. This information can be used as evidence that the affected organization did as much as possible to thwart the violation. It might also give the authorities the forensic data needed to investigate the event and potentially identify the attackers.

5. Enforce business policies effectively

Enforcing business policies in a remote work environment is not always easy. The final key similarity between IDS and IPS is their ability to help ensure highly secure and ethical business operations through policy enforcement.

Intrusion detection and prevention solutions can be set up to enforce security policies at the enterprise network level. For instance, if company policy mandates using a specific VPN service, IPS can be configured to block traffic from other VPNs. The logs and reports generated by these tools can also be used to draft training modules and create new operational and security policies.

These security solutions can detect inappropriate cyber behavior, capture it, and process it as a security event. This makes it possible to monitor chronic or suspected policy abusers remotely and collect evidence of malicious behavior.

See More: What Is Privileged Access Management (PAM)? Definition, Components and Best Practices

Top 5 Differences Between IDS and IPS

While intrusion detection and prevention systems are similar in numerous important ways, they also have a few key differences in scope, location, type, level of intervention required, and configuration.

Scope
Intrusion Detection System
Intrusion Prevention System

IDS operates as a monitoring tool that reads and compares network packets against a known threat signatures database or a baseline created using

machine learning

.

An IDS is built for detection and surveillance and will take minimal action by itself when a threat is detected.

IPS is a control-based solution that either accepts or rejects network packets based on predetermined rulesets.

An IPS can do the job of an IDS, but vice-versa is not possible.

Location and Range
Intrusion Detection System
Intrusion Prevention System

IDS operates across the enterprise network, monitoring and analyzing traffic in real-time. Packets anywhere on the network are scanned for indicators of compromise, and any detected threats or anomalies are flagged.

Once a violation of the configured security policies–such as a port scanner, ransomware, or malware–is detected, IDS alerts human security personnel for further action.

IPS operates typically in the same network location as a firewall, intercepting traffic at the juncture where the internal network meets the internet at large.

Once a threat is detected, IPS stops the flow of malicious traffic.

Unlike IDS, IPS can shut down the threat and prevent the malicious packets from reaching their target while alerting security personnel.

However, its range can be limited compared to IDS. IPS can rely on IDS to increase its range of surveillance.

Types
Intrusion Detection System
Intrusion Prevention System
Host-based IDS (HIDS)

is deployed at the endpoint level to protect individual devices from cyber threats. This type of IDS can monitor network traffic as it flows in and out of a device. It can also track running processes and examine system logs.

HIDS only protects its host machine, which means it does not have access to the complete network data and the associated context for decision-making. However, it has granular visibility into the workings of the host device.

Network-based IDS (NIDS) monitors the entire enterprise network. It tracks all the traffic that passes to and from every device on the network and makes decisions by studying the metadata and content of packets.

NIDS has a wider viewpoint than HIDS, giving it more contextual information and allowing it to detect widespread threats. However, such systems might not have granular visibility into the devices that they secure.

Host-based IPS (HIPS)

is a cybersecurity software that is located on individual clients and servers. It monitors events and thwarts attacks at the device level.

Network-based IPS (NIPS) is deployed within the enterprise network infrastructure. It monitors all the data in the complete network and thwarts threats before they can reach their targets.

Wireless IPS (WIPS) is a network security device that monitors radio waves for unauthorized access points and automatically takes countermeasures to prevent them from causing damage to enterprise systems.

Intervention Level Required
Intrusion Detection System
Intrusion Prevention System

IDS relies on the intervention of IT teams or other security systems to prevent threats. It is capable of scanning networks for known and previously unknown threats. However, it is not able to use the results of these scans to implement a predetermined plan of action and address identified threats independently.

If another solution, such as IPS, is not implemented, IDS would require a dedicated human resource to deal with malicious traffic once spotted.

IPS is a highly proactive cybersecurity solution that leverages either a database of the latest threat signatures or an ML-powered behavior model to detect and prevent cybersecurity violations.

Unlike IDS, IPS solutions are capable of autonomously stopping threats before they are able to cause any damage.

Configuration
Intrusion Detection System
Intrusion Prevention System

IDS is generally set to operate in the inline mode.

Security teams can specify the expected action of the IDS once a threat is detected. For instance, IDS can create a log of the event, transmit a notification to a pager or a console, or communicate a command to a router or firewall.

Logging the activity provides forensic information that allows security teams to analyze successful exploits. Logs can also be used to update router, firewall, and server policies to stop such events from recurring.

Enterprises normally set up IDS to handle logs and alerts while the routers, firewalls, and servers fight threats.

In a network, IPS is placed behind the firewall.

IPS is generally configured to operate either as an end host or in the inline mode. Behavior-based IPS might occasionally raise false alarms as harmless anomalies are caught in its filter.

By fine-tuning the configuration of this type of IPS, it can be set to recognize normal network traffic and let it through, thus detecting threats without disrupting day-to-day network operations.

Takeaway

In the post-pandemic world, cyber threats have become more dangerous than ever before. Network security systems that integrate signature databases and artificial intelligence, such as IDS and IPS, are powerful tools that enable IT teams to bolster their security posture against advanced threat actors.

These security platforms are similar in terms of the benefits that they offer and mode of operation. However, they differ in configuration, intervention level required, scope, type, location, and range. When combined, these cybersecurity solutions work together to prevent malicious network data from reaching its destination while alerting security personnel for remedial action.

Did this article give you an in-depth overview of the key differences and similarities between intrusion detection and prevention systems? Let us know on LinkedInOpens a new window , TwitterOpens a new window , or FacebookOpens a new window ! 

MORE ON NETWORK SECURITY