What Is Snort, How It Works, and Its Integration with SIEM for Cybersecurity

You can’t defend against what you can’t see. That’s why the first essential requirement in cybersecurity is to know everything happening in your systems. To achieve this, we implement an IDS (Intrusion Detection System)—a solution that tirelessly monitors every corner of your network like the Eye of Sauron, instantly alerting you to breach attempts and suspicious behavior. Among IDS options, Snort stands out as one of the most popular.
Its effectiveness, open-source nature, Cisco-backed development, and availability for Windows, Linux, and Unix platforms make it a go-to solution for many organizations.
When working in tandem with a SIEM (Security Information and Event Management) platform—which can provide advanced, centralized analysis and alerting, and even trigger defensive actions (by sending in the Nazgûl—or the SOC team, which is basically the same)—Snort helps secure your own private Mordor effectively.
In this article, we’ll explore how Snort works and how it integrates with a SIEM solution like Pandora SIEM for more robust network protection.

How Snort Works

Snort is a software solution that monitors your network by analyzing packets as they pass through —think of it as a police dog at the airport. It also offers certain preventive capabilities, which is why it defines itself as an IPS (Intrusion Prevention System).
Snort operates based on rules, that define what constitutes potentially malicious activity. Following these rules, when Snort detects traffic that matches a predefined pattern, it raises an alert. Imagine it flipping through “Wanted” posters from a Western movie and comparing them against the network traffic—this enables it to detect DDoS ttacks, port scans, buffer overflows, and more.
But Snort doesn’t stop there. It’s a hybrid tool that combines signature-based detection (rules), protocol analysis, and to a certain degree, anomaly detection.
Snort uses two types of rule sets:

• Community Ruleset– Freely available and maintained by expert users around the world. You can download and update these at no cost.
• Subscriber Ruleset– Developed, tested, and maintained by Cisco Talos, these premium rules are available via subscription and offer Cisco-grade detection capabilities.

Each rule follows a specific syntax, consisting of a header (the initial portion) and options (defined at the end).
When writing or modifying these rules, the most critical part is the beginning of the header, which specifies the action Snort should take when it matches a pattern. The main actions include:

• alert: It logs the packet and generates an alert.
• log: It logs the packet without raising an alert.
• pass: It ignores the packet entirely.

These are IDS rules, which detect and log activity without taking further action. However, Snort also includes some prevention capabilities through specific actions such as:

• sdrop: The most basic prevention— it blocks the packet without logging it.
• drop: It preventively blocks the packet and logs the event.
• reject: Same as drop, but it also sends a return packet depending on the protocol (TCP reset/ICMP unreachable or UDP port unreachable).

After the action directive, the rest of the rule’s header includes protocol, source and destination IPs and ports, followed by rule options. By understanding this syntax, you may craft virtually any rule. Here’s a simple example that alerts on HTTP traffic:

alert tcp any any -> 192.168.1.0/24 80 (msg:”HTTP Traffic Detected”; flow:to_server,established; sid:100001;)

This rule generates an alert for any TCP traffic from any source IP and port headed toward destination port 80 on the 192.168.1.0/24 subnet. The msg field provides a description, and sid stands for Snort ID, which is used to uniquely identify and manage rules.
As you may see, this Eye of Sauron is highly versatile. You may write your own rules or adapt examples from the community. Snort allows you to:

• Use Community Rules freely as an unregistered user.
• Register to get access to Cisco’s rules, with a 30-day delay compared to paid subscribers.
• Subscribe (individual or enterprise) for real-time access to Cisco’s premium rulesets.

Snort can operate in multiple modes:

• Packet Sniffer Mode: It reads and displays all IP packets passing through the network, like a live network analyzer.
• Packet Logger Mode: It records all packets to a log file for review and auditing by system administrators.
• NIPDS Mode (Network Intrusion and Prevention Detection System): In this mode, Snort not only “sniffs and barks” but can also take preventive action, acting as a basic IPS.

For organizations with simple infrastructures and moderate risk exposure, Snort is excellent—it’s not just an intelligence agency, it’s also your local police force, capable of “simple arrests.” But for enterprises facing more advanced threats—such as those described in MITRE ATT&CK—this may not be enough. Those threats behave more like cloaked Romulan ships, evading detection through sophisticated techniques, requiring a layered security strategy.

Integrating Snort with a SIEM

Snort scans the network with eagle-eyed precision, inspecting every packet that flows through it—which is both a huge advantage and a potential challenge. Whether operating in Sniffer or Logger mode, Snort analyzes every single packet, generating a huge volume of data and potential alerts.
But more data doesn’t automatically mean more knowledge.
In fact, too much raw data can fill your haystack to the brim—while what you’re really after is the needle, and you need to find it before you get pricked. That’s where integration with a SIEM (Security Information and Event Management) comes into play. A SIEM excels at turning raw data into actionable intelligence, filtering out noise and revealing advanced threats.
This is made possible by the SIEM’s ability to correlate events collected by Snort with information from other security components (like EDRs on endpoints, for example). So while Snort monitors network-level activity, the SIEM connects the dots across the entire infrastructure.
While specific Snort-to-SIEM integration depends on the platform you’re using, the basic process typically involves sending Snort’s logs to the SIEM which then includes them in its analysis pipeline.
That way, the SIEM sees the full Matrix.
Some solutions—like Pandora SIEM—can go a step further, performing global correlation and applying Machine Learning to detect complex anomalies that go beyond Snort’s signature-based detection or what’s visible from the network alone. That means you might just catch that cloaked Romulan ship as it crosses into the Neutral Zone.
To get the most out of your Snort + SIEM integration, consider following some key best practices:

• Filter Snort alerts properly: Even if your SIEM can handle advanced analysis and correlation, you don’t want to overload it. Filter out benign traffic (e.g., Windows updates) to avoid alert fatigue.
• Keep both Snort and the SIEM updated.
• Test regularly: Ensure Snort is capturing data properly, and double-check that logs aren’t empty—or worse, filled with irrelevant noise that slows down your SIEM.
• Customize rules and alerts: Every organization has a unique threat surface. What’s high-risk for one may be irrelevant for another. Even though Snort and your SIEM come with solid defaults, a security admin should tailor rules to align with the organization’s infrastructure and priorities.

Benefits of Advanced Threat Detection with Snort and a SIEM

The advantages of using Snort and a SIEM together become obvious after reviewing how they complement each other:

• Centralized visibility into security events. Snort doesn’t monitor everything—its view is limited to network traffic. But threats don’t always enter through the front door. A USB drive found in the parking lot might look harmless… until it turns out to be a malicious Rubber Ducky that injects payloads directly into a machine. A SIEM brings visibility to endpoints, applications, user behavior, and more—essentially combining Snort’s Eye of Sauron with other Palantíri that scan every corner of the IT infrastructure.
• More sophisticated threat detection. You can customize Snort’s rule files extensively, but it can’t detect what it can’t see. Multi-vector attacks, lateral movement, or credential-based attacks often occur beyond the scope of network traffic. A SIEM detects these by correlating logs from multiple sources, not just what Snort observes.
• Automated response capabilities through SIEM. Going further than the basic IPs features of Snort.
• Fewer false positives and reduced manual workload IDS tools generate huge volumes of alerts, many of which turn out to be noise, but that a SIEM is capable of filtering. Saving analysts time, vision, and sanity.

Challenges of Using Snort with a SIEM

Everything we’ve covered so far sounds great—like turning your IT kingdom into a fortress where no two hobbits with a cursed ring are going to sneak in and bring ruin.
But, as with any epic defense, this comes at a price and with several challenges:

• The eternal trade-off between money and knowledge. Snort is open source, so it doesn’t cost you any money to acquire it—but nothing in life is truly free. You pay in technical expertise. Deploying Snort, tuning its rules, and integrating it with a SIEM requires a solid understanding of networking, security, and log management.
• Ongoing maintenance and constant updates.
• Verifying that updates don’t break things Every time you apply a new rule or update either Snort or your SIEM, you need to test.
• Noise needs fine-tuning techniques like: using thresholds to raise the bar before triggering alerts; customizing rules to your environment and ignoring routine traffic (like HTTP requests on known-good web servers), unless you truly need to be alerted every time someone browses a site.

Snort gives organizations of any size access to enterprise-grade intrusion detection capabilities. When paired with a strong SIEM, you can deploy a multi-layered defense that watches, analyzes, and responds to threats in real time. But don’t expect plug-and-play magic. This combo demands planning, tuning, and care.
Still, for any organization with even modest IT complexity—especially those following frameworks like NIST, under regulations like NIS2, or where a breach could cost dearly—Snort + SIEM isn’t just a smart choice, it’s a critical one.