Implementing OT Network Traffic Analysis with Nozomi

When to Use

• When deploying passive OT network monitoring using Nozomi Networks Guardian sensors
• When requiring asset visibility without active scanning in sensitive ICS environments
• When building a Nozomi-based OT SOC with centralized management via Vantage or CMC
• When integrating OT network monitoring with Fortinet, Splunk, or ServiceNow ecosystems
• When monitoring compliance with IEC 62443 network segmentation policies

Do not use for active vulnerability scanning of OT devices (see performing-ot-vulnerability-scanning-safely), for environments standardized on Dragos (see implementing-dragos-platform-for-ot-monitoring), or for IT-only network monitoring.

Prerequisites

• Nozomi Networks Guardian sensor (hardware, VM, or container)
• Network TAP or SPAN port configured on monitored OT network segments
• Nozomi Vantage (cloud) or Central Management Console for multi-sensor management
• Nozomi Threat Intelligence subscription for updated detection signatures
• Network architecture documentation for sensor placement planning

Workflow

Step 1: Deploy Guardian Sensors for Passive Monitoring

#!/usr/bin/env python3
"""Nozomi Guardian Deployment Manager and Alert Analyzer.

Manages Nozomi Guardian sensor deployment validation, asset inventory
extraction, and threat alert analysis for OT environments.
"""

import json
import sys
from collections import defaultdict
from datetime import datetime
from typing import Dict, List, Optional

try:
    import requests
except ImportError:
    print("Install requests: pip install requests")
    sys.exit(1)


class NozomiGuardianManager:
    """Manages Nozomi Networks Guardian for OT monitoring."""

    def __init__(self, guardian_url: str, api_token: str, verify_ssl: bool = False):
        self.guardian_url = guardian_url.rstrip("/")
        self.session = requests.Session()
        self.session.headers.update({
            "Authorization": f"Bearer {api_token}",
            "Content-Type": "application/json",
        })
        self.session.verify = verify_ssl

    def get_nodes(self, node_type: Optional[str] = None) -> List[Dict]:
        """Retrieve discovered network nodes (assets)."""
        params = {}
        if node_type:
            params["type"] = node_type
        resp = self.session.get(f"{self.guardian_url}/api/v1/nodes", params=params)
        resp.raise_for_status()
        return resp.json().get("result", [])

    def get_alerts(self, severity: str = "high", limit: int = 100) -> List[Dict]:
        """Retrieve security alerts."""
        params = {"severity": severity, "limit": limit, "status": "open"}
        resp = self.session.get(f"{self.guardian_url}/api/v1/alerts", params=params)
        resp.raise_for_status()
        return resp.json().get("result", [])

    def get_links(self) -> List[Dict]:
        """Retrieve communication links between nodes."""
        resp = self.session.get(f"{self.guardian_url}/api/v1/links")
        resp.raise_for_status()
        return resp.json().get("result", [])

    def get_vulnerabilities(self) -> List[Dict]:
        """Retrieve detected vulnerabilities."""
        resp = self.session.get(f"{self.guardian_url}/api/v1/vulnerabilities")
        resp.raise_for_status()
        return resp.json().get("result", [])

    def validate_deployment(self):
        """Validate Guardian sensor deployment and coverage."""
        print(f"\n{'='*65}")
        print("NOZOMI GUARDIAN DEPLOYMENT VALIDATION")
        print(f"{'='*65}")
        print(f"Guardian URL: {self.guardian_url}")
        print(f"Validation Time: {datetime.now().isoformat()}")

        # Check system status
        try:
            resp = self.session.get(f"{self.guardian_url}/api/v1/system/status")
            if resp.status_code == 200:
                status = resp.json()
                print(f"\n--- SYSTEM STATUS ---")
                print(f"  Version: {status.get('version', 'N/A')}")
                print(f"  Uptime: {status.get('uptime', 'N/A')}")
                print(f"  Packets Processed: {status.get('packets_processed', 'N/A')}")
                print(f"  Threat Intelligence: {status.get('threat_intelligence_version', 'N/A')}")
        except requests.RequestException as e:
            print(f"  [!] System status unavailable: {e}")

        # Asset discovery summary
        nodes = self.get_nodes()
        print(f"\n--- ASSET DISCOVERY ---")

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