Intrusion Prevention System (IPS): Definition, How It Works, and Differences from IDS

In today’s digital era, securing company systems is not enough by just installing a standard firewall. Cyber attacks are becoming increasingly sophisticated and can infiltrate unnoticed if systems only react after problems occur.

Therefore, a security system capable of acting faster and automatically is needed. One such system is the Intrusion Prevention System (IPS). An IPS functions like a digital security guard that not only monitors network traffic but also immediately stops suspicious activity before causing damage.

For companies, understanding IPS is crucial for creating layered data protection.

What Is an Intrusion Prevention System (IPS)?

Intrusion Prevention System (IPS) is a network security system tasked with detecting and simultaneously stopping cyber attacks before they damage the system.

Unlike security systems that merely monitor, an IPS is installed directly in the network traffic path (inline). This means every incoming and outgoing data packet is inspected directly.

If suspicious or malicious data is found, the IPS immediately blocks it automatically, without waiting for human intervention. This way, attacks can be stopped faster, and the risk of system damage can be minimized.

What Is the Difference Between IDS and IPS?

Often the term IPS is juxtaposed or even confused with Intrusion Detection System (IDS). Indeed, both are designed to recognize network threats, but their working mechanisms and impact on the system are very different.

For better understanding, here is an analogy of the difference between IDS and IPS:

• IDS is like a surveillance camera (CCTV). It can see if something suspicious happens and give a warning, but it cannot stop the event itself.
• IPS is like an active security guard. When seeing something dangerous, it immediately takes action to stop it before bad things happen.

Here is a deep technical comparison between the two systems:

Benefits of IPS

Implementing IPS provides a dynamic security layer that traditional firewalls cannot fulfill. The main benefit is security response automation, reducing the IT team’s burden in monitoring threats 24/7.

IPS is also effective in risk mitigation against zero-day exploits (security vulnerabilities without patches yet). With behavioral analysis, IPS can hold off new attacks whose patterns are not yet registered in antivirus databases.

Additionally, IPS usage helps companies meet regulatory compliance standards like PCI-DSS, HIPAA, and UU PDP. This aligns with good data governance principles to protect sensitive customer information.

Types of IPS

To protect various aspects of IT infrastructure, IPS is categorized into several types based on placement location. Choosing the right type depends on network architecture and vulnerable points to protect.

1. Network-based IPS (NIPS)

NIPS is installed at critical locations in the network, for example at internet gateways or between internal company networks. With this position, NIPS can monitor all data passing through that network area.

This system works by analyzing data traffic patterns to look for suspicious activity. Because it is installed right after the firewall, NIPS serves as an initial defense layer helping prevent external attacks before they go deeper into the network.

2. Host-based IPS (HIPS)

HIPS is installed directly on individual endpoints, such as servers, laptops, or employee desktop computers. This system monitors inbound and outbound traffic specific to that device only.

The advantage of HIPS is its ability to detect attacks that might slip past NIPS, especially threats originating from within the network (insider threat) or via physical media like USB.

3. Wireless Intrusion Prevention System (WIPS)

WIPS is designed specifically to monitor wireless networks (Wi-Fi). This system detects illegal access points (rogue access points) and unauthorized devices trying to connect to the corporate network.

WIPS is very important for companies with BYOD (Bring Your Own Device) policies or those with open workspaces. This system prevents Man-in-the-Middle attacks often occurring in wireless networks.

4. Network Behavior Analysis (NBA)

Network Behavior Analysis (NBA) or Behavior-based IPS works by learning “normal” traffic patterns in your network.

When anomalies occur, such as sudden data spikes or connections to unusual ports, NBA will consider them threats. This approach is highly effective for detecting DDoS attacks and new vulnerabilities that do not yet have digital signatures.

How Does an Intrusion Prevention System Work?

IPS works through a continuous cycle involving monitoring, analysis, and execution. This process happens in milliseconds to ensure security without sacrificing service availability.

1. Data Collection

The first step is packet sniffing. IPS captures data packets passing through the network interface in real-time.

The system not only looks at packet headers (origin and destination) but also performs Deep Packet Inspection (DPI) to view the payload content of that data.

2. Data Analysis

After data is collected, IPS analyzes it using several methods.

• Primary method includes signature-based matching comparing packets with known threat databases.
• Secondary method is statistical anomaly analysis (anomaly-based) comparing current traffic with network normal baselines. The third method is stateful protocol analysis ensuring compliance with internet protocol standards.

3. Threat Detection

If analysis finds a match with attack signatures or significant behavioral deviation, the system will flag it as a threat.

This stage is crucial to minimize false positives. Modern IPS often uses artificial intelligence to improve detection accuracy.

4. Prevention Actions

Once a threat is confirmed, IPS takes preventive action according to policy configuration. This action can be dropping the malicious packet so it doesn’t reach the destination.

Other actions include terminating TCP connections (reset connection), blocking the attacker’s IP address, or automatically reconfiguring firewalls or routers to close access.

5. Reporting and Logging

Every detected incident and action taken will be recorded in system logs. This data is vital for audit trails and post-incident digital forensics.

These reports help administrators understand attack trends faced by the organization and refine future security policies.

Attacks Detected by IPS

IPS is designed to handle various complex network attack vectors. Here are some main threats effectively mitigated by this system.

• Address Resolution Protocol (ARP) Spoofing
  This attack fakes MAC addresses to redirect network traffic to the attacker’s computer. IPS detects IP-to-MAC mapping inconsistencies and blocks fake ARP packets.
• Buffer Overflow
  Attackers send excess data to application memory to overwrite program code and take over the system. IPS detects execution instruction patterns (shellcode) commonly used in these exploits within network payloads.
• Distributed Denial of Service (DDoS)
  This attack floods the network with fake traffic to paralyze services. IPS uses behavioral analysis to identify abnormal traffic spikes and block attack sources without disturbing legitimate users.
• IP Fragmentation
  This method breaks malicious packets into small fragments to evade security detection. IPS reassembles fragments in memory before forwarding, so malicious payloads can be identified intact.
• Operating System (OS) Fingerprinting
  Attackers scan the network to know the target’s operating system type to find specific vulnerabilities. IPS can detect these scanning patterns and obfuscate network responses to confuse attackers.
• Ping of Death
  This legacy attack sends ping packets exceeding the IP protocol maximum size to cause crashes on target systems. Although modern systems are more immune, IPS still blocks such malformed packets.
• Port Scanning
  This is reconnaissance activity to find open entry points (ports) on target servers. IPS recognizes sequential or random scanning patterns and can proactively block scanner IPs.
• Server Message Block (SMB) Probes
  SMB protocols are often targets for ransomware attacks (like WannaCry) to spread within networks. IPS monitors suspicious SMB commands and prevents remote code execution via this protocol.
• Smurf
  This attack uses IP spoofing to flood targets with ICMP (ping) responses from many devices on the network. IPS detects and discards unreasonable ICMP broadcast requests.
• Secure Sockets Layer (SSL) Evasion
  Attackers often encrypt malicious traffic using SSL/TLS to be unreadable by security tools. Advanced IPS has SSL decryption capabilities to inspect threats hidden inside encrypted traffic.
• SYN Flood
  This attack floods servers with TCP connection requests (SYN) without completing them (ACK), consuming server resources. IPS acts as an intermediary validating connections before forwarding to destination servers, an effective technique against brute force attacks and connection floods.

Conclusion

Intrusion Prevention System (IPS) is a mandatory component in enterprise network security architecture. Its ability to detect and stop attacks in real-time provides vital protection against service disruption and data theft.

However, IPS only protects the network and infrastructure layers. In today’s digital era, threats often enter via legitimate but leaked user credentials, an area unreachable by IPS alone. Therefore, a holistic security strategy must also include robust identity management.

To complete your network defense with impenetrable access security, Adaptist Prime arrives as an integrated Identity & Access Management (IAM) solution. Prime ensures that even if your network is secure, only the right people have access to company data.

With the support of Adaptist Prime, your company can build a digital ecosystem that is secure, time-efficient, and ready to grow without sacrificing data protection or user convenience.

FAQ

1. Do I still need a Firewall if I already use IPS?

Yes, firewalls and IPS have different but complementary functions. Firewalls filter traffic based on IP and Port rules, while IPS inspects packet content to look for malicious material.

2. Will IPS slow down company internet connection?

Poorly configured IPS or inadequate hardware can cause latency (bottleneck). However, modern enterprise-grade IPS solutions are designed to process gigabit traffic with minimal impact on speed.

3. What is the difference between Host-based IPS (HIPS) and Antivirus?

Antivirus generally works based on known malicious file signature databases and runs periodically. HIPS monitors system behavior and network traffic in real-time to prevent malicious code execution, even those without antivirus signatures.

4. Does Adaptist provide IPS solutions?

Adaptist focuses on identity security and data compliance layers (Layer 7 and Governance). We recommend using network IPS from trusted vendors, then combined with Adaptist Prime for access control.