IDS vs IPS: Definitions and Why You Need Both

What is the Difference Between IDS and IPS?

If you’re a small business owner, the last thing you want is for your firm to fall prey to a cyberattack. The bad news is, the likelihood of this happening has only increased since we started living in a technological age.

And the question is, will your cybersecurity system be able to withstand it when it does?

This is why having intrusion detection systems and intrusion prevention systems in place is extremely important. Think of these software applications as similar to the missile defense system on a fighter jet.

Their purpose is to detect and destroy security threats before they can cause any harm, making your business invulnerable to cyberattacks.

What is an Intrusion Detection System (IDS)?

How does an Intrusion Detection System Work?

Because they only need to monitor network traffic for malicious activity or security policy violations, IDS systems are located out-of-band on the network infrastructure. They operate outside of the direct line of communication between the sender and the receiver of information.

There are three main intrusion detection methods that IDS systems use to identify potential threats, namely:

1. Signature-based detection: This method uses signatures stored in a database to identify known threats. When the IDS detects malware or other malicious behavior, it generates a fingerprint or signature. This signature is added to the database that is used by the IDS solution to test network traffic for malicious instruction sequences.

This means that a signature-based IDS achieves high threat detection rates with no false positives. In other words, these systems do not generate false security alerts. This is because all the alerts are generated based on the detection of known threats. However, this means that a signature-based IDS is limited to identifying known threats and is blind to what you would call zero-day vulnerabilities.

2. Statistical anomaly-based detection: This type of IDS solution performs a behavior analysis of the protected system. This is done to determine the “normal” behavior of that particular system. Any future network behavior that differs from what is considered “normal” is then flagged as potentially harmful.

While an anomaly-based IDS can identify unknown threats, generating an accurate representation of the “normal” behavior of the system in question is complex. This is because these IDS solutions must strike a balance between false positives (incorrect alerts) and false negatives (missed detections).

3. Hybrid detection: Hybrid IDS solutions combine both methods of intrusion detection. This allows them to identify more potential threats with lower error rates.

We will now move on to a discussion of the main types of IDS.

What are the Main Types of IDS?

Network Intrusion Detection System (NIDS)

This allows the NIDS system to identify patterns in the behavior of network traffic. So, when any malicious or anomalous activity is detected, such as a change in the standard packet size or traffic load, the NIDS system generates a warning.

Host Intrusion Detection System (HIDS)

A host-based IDS is an inbuilt software package that identifies threats that manage to bypass the network perimeter. It does this by using sensors known as “HIDS agents,” installed on assets, such as computers, servers, and routers.

The HIDS sensors monitor the processes and applications running on these devices, which are also called hosts. Therefore, each host has its HIDS, which will investigate any changes that are made to the system of a particular host and generate a warning when it detects any unauthorized or suspicious activity.

For deeper security visibility, a host-based IDS system is generally deployed together with a NIDS.

Like NIDS, HIDS is also a hybrid IDS solution that utilizes a combination of signature-based detection and anomaly-based detection methods.

HIDS systems can identify a variety of threats, including:

      • Unauthorized access and login attempts
      • Privilege escalation
      • Modification of application binaries, data, and configuration files
      • Rogue processes
      • Critical services that have stopped or failed to run

What is an Intrusion Prevention System (IPS)?

However, you can differentiate between these two systems by examining their functions and where they fit into the network.

As you already know, an IDS monitors traffic at various points in the network, providing visibility regarding its security status and alerting you to any threats that need to be investigated.

How does an Intrusion Prevention System work?

It works like this: when a firewall receives a network packet, it goes through its rules, looking for one that says “allow this packet through.” If it runs through all of its rules and reaches the end without finding a rule saying “allow this packet through,” then the packet is denied entry into the network.

What happens is, when a network packet appears at the IPS, the IPS searches through its rules to look for a reason to drop the packet. If it cannot find a single rule that says “block this known security problem,” it will ultimately allow the packet to pass through. In the absence of a reason to drop it from the network, the IPS will allow the packet to pass.

However, if the IPS comes across a rule that identifies a packet as malicious, it will block all future traffic from the offending source IP address.

What are the Main Types of IPS?

Network Intrusion Prevention System (NIPS)

Like NIDS, its purpose is to monitor the entire network. However, unlike NIDS (which is a passive security system), NIPS can not only detect malicious traffic; it can also prevent it from causing harm to the system.

Host Intrusion Prevention System (HIPS)

Wireless Intrusion Prevention System (WIPS)

Network Behavior Analysis (NBA)

Can IDS and IPS Work Together?

As you are aware by now, having intrusion detection and intrusion prevention systems in place will protect your small business against network intrusion.

So, the short answer to the question is yes.

However, the other question that can be raised in this regard is: is it necessary to have both?

Well, that partly depends on the kind of functions that you want each system to perform. If you’re looking for a system that provides visibility into your network security, then an IDS is your best option. Conversely, if you want a system that gives control, then an IPS might be more suited to your needs.

Bear in mind, though, that a security tool like an IDS that provides visibility is only helpful when there is someone to look at what it is telling you. Similarly, with an IPS, you will have to configure it to match your network to put up a proper defense against threats.

Conclusion

The main difference between them is that intrusion detection systems passively identify network intruders and alert you to their presence, whereas intrusion prevention systems will actively block threats when detected.

Keep Your Small Business Safe!