When it comes to open-source intrusion detection tools, there are only three systems that any organization should be looking at. Suricata, Snort, and Zeek stand above the rest as the most effective open-source network security tools available. But how are you supposed to choose which is right for you? This blog post will provide an introduction to each to help you decide which might be the best for your needs.
What is open-source intrusion detection?
An open-source intrusion detection system (IDS) is a security software system that monitors an organization’s network for malicious activity and is freely available for anyone to use, modify, and distribute. Instead of relying on pre-built commercial security software, open-source intrusion detection tools offer a different approach based on transparency, flexibility, customizability, and community collaboration.
The core idea is that the IDS’s code is open for anyone to download, use, alter, and improve. This openness allows for a wide range of individuals to contribute to its development while also tailoring the system for their own unique needs. The rules used by the IDS are also commonly shared in various threat intelligence sharing platforms, enabling users to support each other and stay up to date with new and emerging threats.
Open-source intrusion detection tools are an incredibly cost-effective option for many organizations because they eliminate the licensing costs associated with commercial security software, making it an attractive option for personal use or budget-conscious organizations.
What are 3 intrusion detection systems?
There are several popular open-source IDS options available, each with its own strengths and weaknesses. Here are three of the most well-known network intrusion detection system examples:
- Snort: Snort is a signature-based open-source Intrusion Detection System (IDS). It inspects network traffic for patterns matching predefined signatures of malicious activity and can be configured to log traffic or even prevent suspicious connections.
- Suricata: Suricata is a high-performance free, open-source IDS. It offers similar functionality as Snort with improved performance due to native multi-threading capabilities. Additionally, Suricata supports deeper packet inspection, allowing analysis of application layer protocols for a more comprehensive security posture. Suricata can be active or passive depending on user configuration and can be used as an IDS, IPS, or network security monitoring (NSM) tool.
- Zeek (formerly Bro): Zeek is a free, open-source network traffic analyzer. Unlike Snort and Suricata, Zeek takes a passive approach, capturing and recording detailed logs of network activity for later analysis. This includes deep inspection of application layer data, providing valuable insights for security investigations and network performance monitoring.
What is an example of a free open-source IDS?
The best network intrusion detection system is Suricata.
Suricata is a powerful network security tool that monitors your network for malicious activity and is freely available under the GNU General Public License (GPLv2). This means anyone can use, modify, and distribute Suricata without any licensing fees.
Suricata is by far the best open-source IDS, known for its efficiency and ability to handle large volumes of network traffic without compromising performance. It uses deep packet inspection to detect more sophisticated threats that might try to hide malicious payloads within seemingly normal data packets. Suricata can be configured as an IDS for passive monitoring or as an IPS for active blocking of unwanted traffic.
Suricata benefits from a large and active community that develops and maintains a vast library of rules to identify various threats. These rules are regularly updated and commonly shared on platforms like the Malware Information Sharing Project (MISP). There is even an annual conference for Suricata users called Suricon, which historically provides workshops and lectures on Suricata topics, development, and best practices.
Is Suricata and IPS or IDS?
Suricata is both an intrusion detection system (IDS) and an intrusion prevention system (IPS), but many people are unaware that it can also be configured to function as a network security monitoring (NSM) tool.
In its IDS mode, Suricata continuously monitors your network traffic for suspicious activity. It compares this traffic to a vast database of known threats and pre-defined rules. Users can also include new rule sets and create custom rules. If it detects a potential attack, like malware or a hacking attempt, Suricata issues an alert, allowing you to investigate and take action.
IDS monitoring is more passive than IPS. Suricata monitors the network traffic but does not intervene. This offers a valuable first line of defense, but some organizations might feel overwhelmed by the number of alerts and the presence of false positives, requiring human intervention to sort through alerts to find actual serious and imminent threats.
You can also configure Suricata as IPS. In IPS mode, it doesn't just detect threats, but it actively blocks them. By analyzing traffic patterns and comparing them to its rule set, Suricata can identify and stop malicious attempts before they infiltrate your system. This is a more active strategy than IDS, but false positives could lead to legitimate traffic being blocked due to poorly configured rules. Configuring Suricata as IPS while avoiding unintended consequences requires a deep understanding and expertise in network security.
Learn More About Suricata
To begin learning more about Suricata, we recommend downloading the open-source book published by Stamus Networks titled “The Security Analyst’s Guide to Suricata” — the first practical guide to threat detection and hunting using Suricata, the world’s most popular open-source network security engine.
Written for security operations center (SOC) analysts and threat hunters who use Suricata to gain insights into what is taking place on their networks, the book provides vital information on entry points and an in-depth analysis of the most important Suricata features.
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