What is Suricata?

Suricata is an open-source, high-performance engine for Network Security Monitoring (NSM), Intrusion Detection (IDS), and Intrusion Prevention (IPS). It is a powerful tool that analyzes network traffic in real-time, looking for signs of malicious activity such as hacking attacks, malware, or port scanning attempts.

It is the main competitor to the older Snort project, but offers a modern multi-threaded architecture, allowing it to perform much more efficiently on modern multi-core processors.

How Does Suricata Work?

Suricata operates on several levels:

  1. Packet Capture: It uses modern mechanisms like AF_PACKET (Linux) or PF_RING to efficiently collect packets from the network interface.
  2. Decoding and Analysis: It understands and decodes network protocols (TCP/IP, UDP, ICMP) and application layers (HTTP, DNS, TLS, SMB, and many others).
  3. Signature Matching: It compares analyzed traffic against a database of rules (signatures). If a packet matches a rule (e.g., “detected SSH login attempt from suspicious IP”), Suricata takes action.
  4. Logging (EVE JSON): This is one of Suricata’s biggest advantages. All events – alerts, flow metadata, file information – are saved in a single, standardized JSON format (eve.json). This facilitates integration with SIEM systems like the ELK Stack (Elasticsearch, Logstash, Kibana).

IDS vs. IPS: Two Modes of Operation

  • IDS (Intrusion Detection System): Suricata works passively. It copies traffic from the network (e.g., via port mirroring), analyzes it, and generates alerts when it detects something suspicious. It does not block traffic, only warns.
  • IPS (Intrusion Prevention System): Suricata works “inline”, between the internet and your network. It analyzes every packet before letting it through. If it detects an attack, it can actively block it (drop the packet).

Installation and First Steps (Ubuntu/Debian)

Suricata is available in most repositories, but it’s worth using the official PPA for the latest version.

  1. Installation:

    sudo add-apt-repository ppa:oisf/suricata-stable
sudo apt update
sudo apt install suricata

  2. Updating Rules: Suricata needs rules to know what to look for. The suricata-update tool downloads a free rule set (ET Open).

    sudo suricata-update

  3. Configuration: The main file is /etc/suricata/suricata.yaml. You need to define the listening network interface and your home network IP ranges (HOME_NET) there.

  4. Starting:

    sudo systemctl enable suricata
sudo systemctl start suricata

Summary

Suricata is the foundation of modern network security. Thanks to multi-threading and JSON support, it is the ideal choice for both small offices and massive data centers. Deploying Suricata is the first step to stop guessing what is happening in your network and start seeing it.