Like firewalls, intrusion detection systems (IDS) are incredibly popular early lines of defense for many organizations. For those who are unfamiliar with intrusion detection systems in cyber security but are familiar with the firewalls, you may be curious what the differences are and whether or not they can work together. This blog post seeks to answers all of those questions, but first let’s review a little bit about IDS.
What is IDS?
An intrusion detection system (IDS) is a cybersecurity tool that analyzes system activity or network traffic for patterns that might indicate an attack. These patterns could be:
- Unusual login attempts (repeated failed logins, access from unexpected locations)
- Attempts to exploit known vulnerabilities in software
- Denial-of-service attacks flooding the system with traffic
By identifying these patterns, IDS helps security personnel identify potential threats and take necessary steps to mitigate those threats. There are two main types of intrusion detection systems:
- Network Intrusion Detection System (NIDS): This type of system monitors network traffic for suspicious activity, such as port scans, denial-of-service attacks, or attempts to exploit vulnerabilities.
- Host-based Intrusion Detection System (HIDS): This type of system is installed on individual devices and monitors the activity on those devices for suspicious activity.
When an IDS detects suspicious activity, it will typically send an alert to a security administrator. The security administrator can then investigate the alert and take appropriate action, such as blocking the attacker's IP address or shutting down a compromised device.
Intrusion detection systems are an important part of a layered security defense. They can help to identify and respond to attacks that other security measures, such as firewalls, may miss. However, it's important to note that IDS systems are not foolproof and can sometimes generate false alarms or cause alert fatigue.
What is the difference between IDS and firewall?
The main difference between a firewall and IDS is that a firewall is simply a control mechanism, while an intrusion detection system actually detects and alerts on potentially malicious traffic. Firewalls enforce a set of pre-defined rules to permit or deny traffic flow based on characteristics like IP addresses, ports, protocols, or applications. It allows only authorized traffic through the network perimeter.
IDS is a monitoring and detection system. It analyzes network traffic for malicious activity or suspicious patterns that might indicate an ongoing attack. IDS doesn't directly block traffic but raises alerts for further investigation and potential response by security personnel. However, some IDS solutions, like Suricata, can be configured to function as an IPS. In this instance, the IPS can actually block traffic much like a firewall. Some organizations opt to use an IPS instead of a firewall, while others use a firewall and an IDS together.
Does IDS go before or after firewall?
The ideal IDS placement in network security depends on your specific needs and resource limitations. There are two main approaches:
IDS after the Firewall (Most Common):
- Advantages:
- Reduced Load on IDS: The firewall acts as a first filter, blocking a significant portion of unwanted traffic before it reaches the IDS. This improves the efficiency of the IDS by focusing its resources on analyzing legitimate traffic for suspicious activity.
- Focus on Internal Threats: Placing the IDS inside the network allows it to monitor for malicious activity originating from within as well as external threats that bypassed the firewall.
- Disadvantages:
- Potential Security Gap: Malicious traffic that slips through the firewall could reach the IDS before being blocked.
IDS before the Firewall (Less Common):
- Advantages:
- Early Detection: This provides the potential to know about threats before they even reach the firewall, offering an extra layer of protection.
- Reduced Network Load: Blocking some threats before they enter the internal network can lessen the overall load on network resources.
- Disadvantages:
- Increased Resource Consumption: The IDS will need to analyze all incoming traffic, including a larger volume of unwanted traffic, potentially impacting performance.
- Limited Visibility into Internal Threats: Primarily focuses on external threats.
Here are some additional factors to consider:
- Network Size and Complexity: For larger networks with complex traffic patterns, placing the IDS after the firewall can be more efficient.
- Security Priorities: If internal threats are a major concern, placing the IDS inside the network might be more important.
- IDS capabilities: Some advanced IDS systems, like Suricata, can handle the increased load of being placed before the firewall.
Ultimately, the best placement depends on your specific situation. It's recommended to consult with a network security professional to determine the optimal placement for your network environment.
Can IDS and firewall work together?
Yes, IDS software and firewalls can and absolutely should work together to provide a layered defense for your network security. They complement each other in different ways:
- Firewall: Controlling incoming and outgoing traffic based on predefined rules. It allows legitimate traffic and blocks suspicious connections.
- IDS: Monitors network traffic for malicious activity. It doesn't directly block traffic, but it can alert administrators about potential attacks.
Here's why they work well together:
- Reduced Load: Firewall filters out most obvious malicious traffic, reducing the burden on the IDS to analyze safe traffic.
- Deeper Inspection: IDS can delve deeper into allowed traffic, looking for anomalies that might bypass the firewall's rules.
- Multi-layered Defense: Together, they provide a stronger defense against various threats.
Explore a modern alternative
IDS is undoubtedly a powerful and effective means to detect known threats on your organization’s network. Unfortunately, most IDS deployments are riddled with false positives, provide limited threat detection, and lack sufficient visibility into anomalous activity and subtle attack signals. Traditional IDS vendors have failed to innovate in ways that solve these challenges, leading to inefficient or downright ineffective threat detection.
You need a network security platform that doesn’t generate an endless stream of useless alerts across part of your network, and instead automatically identifies alerts of interest and notifies you of only serious and imminent threats. Your organization deserves response-ready detection with visibility into your entire network regardless of the environment with easy access to all the contextual evidence you need to stop an attack before it can cause damage. Replace your legacy IDS with a modern network detection and response platform that gives you these features and more.
The Stamus Security Platform™ is a network-based threat detection and response solution that eliminates the challenges of legacy IDS while lowering your response time. Stamus Security Platform harnesses the full potential of your network, bringing state-of-the-art threat detection, automated event triage, and unparalleled visibility to the security team.
Book a demo to see if the Stamus Security Platform is right for your organization.
