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IDS/IPS Placement

Intrusion Detection Systems (IDS) and Intrusion Prevention Systems (IPS) are critical components of network security infrastructure that help detect and respond to potential security threats. Their placement within a network is essential for effective monitoring and protection.

How IDS/IPS placement typically works:

Perimeter Placement:

External Facing: IDS/IPS can be placed at the network perimeter, where they monitor incoming and outgoing traffic between the internal network and the Internet. This placement allows them to detect and block potential threats before they enter or leave the network. It is sometimes referred to as a North-South placement.

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Internal Placement:

Internal Segments: IDS/IPS can also be deployed within internal network segments to monitor traffic between different network parts. This placement helps detect and prevent lateral movement of threats within the network, such as malware spreading from one workstation to another. It will, at times, be referred to as an east-west placement.

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Host-based Placement:

Endpoints: Host-based IDS/IPS software can be installed directly on individual computers or servers to monitor and protect them from internal and external threats. This placement helps detect and prevent attacks targeted at specific hosts.

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In-Line vs. Out-of-Line Deployment:

  • Inline Deployment: In this configuration, IDS/IPS devices are placed directly in the path of network traffic, allowing them to inspect and potentially block malicious traffic in real-time actively. While effective, inline deployment can introduce latency and single points of failure. AN IPS Must be placed inline.  
  • Out-of-Line Deployment: IDS/IPS devices can be deployed out-of-line, monitoring a copy of network traffic without actively participating in the data flow. This approach reduces the risk of disruption to network traffic but may delay response times.  

Strategic Placement Based on Risk:

  • Cyber key terrain (CKT): IDS/IPS should be strategically placed to protect the network's critical assets and sensitive data. This could include placing them near servers hosting valuable information or at chokepoints where network traffic converges.  
  • High-Risk Areas: IDS/IPS deployment should consider high-risk areas within the network, such as wireless networks, remote access points, or DMZs (Demilitarized Zones), which attackers are more likely to target.

Scalability and Coverage:

  • Network Scale: The placement of IDS/IPS should account for the size and complexity of the network, ensuring comprehensive coverage while maintaining scalability.
  • Traffic Visibility: IDS/IPS placement should provide adequate visibility into network traffic, including encrypted traffic, to effectively detect and respond to threats.