ntopng holds a clear lead as the primary tool recommended for network traffic analysis. For cost-conscious buyers seeking open-source security tools in small environments, no single option emerges as the outright favorite.
If you want better visibility into network traffic through your firewall, there are several software options that can help you see who is communicating with whom, which applications and protocols are being used, how much bandwidth is consumed, and whether traffic looks suspicious.
The best choice depends on your existing firewall, whether you want real-time monitoring or deeper security analysis, and whether you can install software directly on the firewall or use a separate monitoring server.
Best software options for network visibility
1. ntopng — Best starting point for traffic visibility
(Best overall starting point)
Shows active connections, top bandwidth consumers, hosts, application protocols, and historical traffic statistics through a web dashboard. It can monitor mirrored traffic or collect flow data from compatible network devices.
Best for: Home networks, small businesses, and troubleshooting.
Cost: Free Community edition; paid editions offer additional capabilities.
Website:
2. Security Onion — Best for comprehensive security monitoring
Combines network metadata, intrusion detection alerts, packet capture, and investigation dashboards. It integrates tools including Zeek and Suricata.
Best for: Security teams, threat hunting, and investigating suspicious activity.
Cost: Free, open-source platform.
Website:
3. Zeek — Best for understanding network behavior
Records detailed connection and protocol metadata, such as DNS, HTTP, SSL/TLS, and other network activity. It is particularly useful for understanding what happened during a suspicious connection.
Best for: Advanced troubleshooting, incident response, and custom analysis.
Cost: Free, open source.
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4. Suricata — Best for detecting threats
Inspects network traffic for suspicious patterns and known attack signatures. Depending on deployment and configuration, it can operate as an intrusion detection system (IDS) or intrusion prevention system (IPS).
Best for: Malware-related traffic, exploit attempts, and suspicious connections.
Cost: Free, open source.
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Which should you install?
Your main goal
My recommendation
See which devices use the most bandwidth
ntopng
See applications and active connections
ntopng
Detect malicious network traffic
Suricata
Investigate suspicious connections in detail
Zeek
Centralize security monitoring and investigations
Security Onion
How to connect it to your firewall
You don't necessarily need to install the software directly on the firewall. In many cases, a separate monitoring computer or server is preferable.
Your firewall
Traffic logs, NetFlow/IPFIX, or mirrored packets
Monitoring server
ntopng, Zeek, Suricata, or Security Onion
Visibility and analysis
Dashboards, traffic history, alerts, and investigations
The connection method matters: firewall logs and flow exports provide useful summaries, while a properly configured network TAP or switch mirror port can provide packet-level visibility. Encrypted traffic will still limit how much application content you can inspect.
Let me narrow this down to your firewall
What firewall are you running? That's the most important detail because it determines which software is easiest to install and integrate.
To get better visibility into your network traffic, you don't typically install software directly onto a production firewall appliance (which can compromise stability or void support). Instead, you configure your firewall to export telemetry data —such as flow logs, SNMP metrics, or packet captures —to an external or internal collector/monitoring server.
The best software options categorized by how they provide visibility include:
Flow Collectors and Analyzers (Best for bandwidth and top-talker visibility)
Akvorado : A modern, open-source flow collector, enricher, and visualizer (using NetFlow/IPFIX/sFlow) that features automated SNMP enrichment and beautiful Sankey diagrams.
Elastiflow / ELK Stack : Combines Elasticsearch, Logstash, and Kibana to ingest, process, and intensely visualize massive amounts of NetFlow, IPFIX, and sFlow data from enterprise firewalls.
Network Monitoring Systems / SNMP Pollers (Best for device health and interface stats)
LibreNMS : A fully featured, open-source auto-discovering network monitoring system that polls firewalls via SNMP to graph interface utilization, CPU, memory, and active sessions over long retention periods.
Paessler PRTG Network Monitor : Highly user-friendly, supporting SNMP, packet sniffing, and flow data tracking out of the box (free tier available for smaller environments).
Zabbix : An enterprise-grade open-source monitoring tool that excels at trend analysis and predicting future traffic utilization based on historical data.
Packet-Level Analyzers and IDS (Best for deep inspection and threat detection)
Wireshark : The gold-standard open-source packet analyzer. While manual, you can feed mirrored switch ports or packet captures (PCAP) from your firewall to it when investigating specific anomalies.
Suricata / Snort : Open-source Intrusion Detection Systems (IDS) that inspect actual packet payloads passing through your network perimeter to alert you on specific application behavior or malicious signatures.[](https://www.wireshark.org/)
If you want to narrow this down, let me know:
What brand or model of firewall you are using
Whether you prefer an open-source or commercial tool
If you are looking for real-time alerting or historical bandwidth reporting
To improve network traffic visibility, a firewall can be integrated with network monitoring, traffic-flow analysis, packet inspection, centralized logging, and threat detection tools. These integrations help you understand who is communicating across the network, which applications consume bandwidth, why connections are blocked, and whether traffic indicates a security threat.
Bandwidth usage, top talkers, source/destination IPs, ports, protocols, and traffic trends. Uses NetFlow, IPFIX, or sFlow where supported.
2. SIEM platforms
Splunk Enterprise Security, IBM QRadar, Microsoft Sentinel
Centralizes firewall logs with other security data to correlate events, investigate incidents, and generate alerts.
3. Packet analyzers
Wireshark, tcpdump
Examines individual packets and protocol details to troubleshoot failed connections, latency, retransmissions, and suspicious traffic.
4. Network Detection and Response (NDR)
ExtraHop RevealX, Vectra AI, FortiNDR
Detects suspicious communications, lateral movement, command-and-control activity, and potential data exfiltration.
5. Intrusion detection and prevention systems (IDS/IPS)
Suricata, Snort
Inspects traffic for known attack signatures and suspicious patterns; IPS configurations can also block matching traffic.
6. Network performance monitoring (NPM)
ManageEngine OpManager, PRTG Network Monitor
Tracks interface utilization, device health, packet loss, latency, and connectivity problems. SNMP is commonly used for device and interface metrics.
7. Centralized logging and log management
Graylog, Elastic Stack
Collects firewall syslog events, policy matches, blocked connections, VPN events, and administrative activity for searching and reporting.
Which should you choose?
For bandwidth and traffic visibility
Start with a NetFlow/IPFIX collector such as SolarWinds NetFlow Traffic Analyzer or PRTG. This is useful for identifying bandwidth-heavy devices, applications, and traffic destinations.
For centralized security monitoring
Forward firewall logs to a SIEM such as Splunk or Microsoft Sentinel to correlate firewall events with endpoint, identity, and cloud activity.
For detailed troubleshooting
Use Wireshark or tcpdump with a firewall packet capture or a network TAP/SPAN port to investigate specific connections.
For advanced threat detection
Add NDR or IDS/IPS to identify suspicious behavior that ordinary firewall allow/deny logs may not reveal.
Recommended integration architecture
Firewall
Traffic rules, connection logs, flow records
Flow collector
NetFlow / IPFIX
Log collector
Syslog / APIs
Packet analyzer
PCAP / deep inspection
NDR / IDS
Threat detection
Central monitoring dashboard / SIEM
Correlated events, traffic analytics, alerts, and investigations
Important: Choose integrations that your firewall supports, and consider enabling only the telemetry you need. Flow records provide efficient traffic summaries, while packet captures offer much greater detail but can consume storage and processing resources. Encrypted traffic also limits what can be inspected without authorized decryption.
For a more specific recommendation, which firewall are you using — Fortinet FortiGate, Palo Alto, Cisco, pfSense/OPNsense, Sophos, or a cloud firewall such as AWS or Azure? I can suggest compatible tools and the integration method.
To significantly enhance network traffic visibility, context, and threat detection, firewalls can be integrated with several specialized security and management tools . Because firewalls primarily act on perimeter enforcement and local stateful inspection, combining them with broader analytical platforms bridges the gap between raw data collection and actionable insight.
SIEM (Security Information and Event Management) Platforms : Tools like Splunk or IBM QRadar ingest firewall syslogs, connection records, and threat prevention alerts. They centralize and correlate this data with logs from endpoints, identity providers, and cloud services to provide an end-to-end timeline of network traffic behavior.[](https://shieldworkz.com/blogs/ndr-network-monitoring-go-beyond-basic-traffic-visibility)
NDR (Network Detection and Response) Solutions : Platforms like or specialized behavioral tools passively analyze mirrored firewall traffic, NetFlow/IPFIX data, or stream telemetry. NDR adds continuous, machine-learning-driven behavioral analysis to spot lateral movement or anomalies that standard firewall rule logs might miss.[](]()](]()]()
Zabbix : A flexible, enterprise-grade open-source monitoring platform that can track firewall performance, interface traffic rates, and packet throughput via SNMP, SSH, or agent logs. With customizable dashboards and trigger mapping, it excels at highlighting historical traffic anomalies and usage spikes.[](https://blog.domotz.com/all/firewall-monitoring-tools/)
PRTG Network Monitor : An all-in-one monitoring tool utilizing customized sensors to poll firewalls via SNMP, packet sniffing, and NetFlow/IPFIX protocols. It breaks down traffic patterns by protocol, IP address, or application type, presenting data through visual, customizable dashboards.[](https://blog.domotz.com/all/firewall-monitoring-tools/)
Grafana with Prometheus / Loki : A modern telemetry stack where Prometheus collects metric data (bandwidth stats, interface counters) and Loki/Promtail aggregates firewall syslogs. Combined with Grafana , you can build tailored, high-performance dashboards visualizing complex traffic patterns and throughput metrics over custom timeframes.
Elasticsearch, Logstash, and Kibana (elastic Stack / ELK) : An enterprise log management and visualization powerhouse. By streaming firewall logs into Elastic, Kibana lets you build sophisticated dashboards mapping geographic traffic origins, top talkers, protocol breakdowns, and denied vs. allowed connection patterns.
If you'd like to narrow down these options, tell me:
What specific firewall vendor or OS (e.g., pfSense, Fortinet, Palo Alto, Cisco) are you running?
Are you looking for a package to run directly on the firewall hardware or on a separate monitoring server?
Several software packages can be deployed directly on a compatible firewall or on a dedicated monitoring system connected to the firewall to gain deeper insight into network traffic. They help identify bandwidth usage, frequently communicating hosts, application protocols, suspicious connections, and long-term traffic trends.
Recommended network traffic analysis packages
1. ntopng
(Best for traffic visibility)
Provides a web dashboard showing bandwidth consumption, top talkers, active connections, application protocols, hosts, and historical trends. It can collect NetFlow, sFlow, IPFIX, and firewall logs, as well as analyze mirrored traffic. It supports Linux, FreeBSD, pfSense, and OPNsense.
Flow Collectors and NPM (Network Performance Monitoring) Tools : Systems utilizing NetFlow, sFlow, or IPFIX (such as SolarWinds NPM or ManageEngine NetFlow Analyzer ) consume flow data exported directly by firewalls. This gives network engineers granular traffic volume visibility, bandwidth utilization breakdowns, and conversation paths without bogging down firewall CPU resources.
SOAR (Security Orchestration, Automation, and Response) Platforms : Tools like Palo Alto Cortex XSOAR or Splunk SOAR integrate directly with firewall APIs. When anomalous traffic or an indicator of compromise (IoC) is identified, the SOAR platform can automatically query the firewall for traffic context, isolate segments, or push dynamic blocking rules.
Threat Intelligence Platforms (TIP) & Feeds : Integrating external threat intelligence feeds directly into your firewall ecosystem enriches standard traffic metadata with up-to-the-minute reputation data on malicious IP addresses, domains, and hashes, instantly illuminating communication attempts with known command-and-control (C2) infrastructure.[](https://stellarcyber.ai/learn/top-ndr-solutions/)
Would you like to explore how to set up log forwarding from a specific firewall vendor (like Palo Alto, Fortinet, or Cisco), or are you looking to design an architecture around a particular tool category like SIEM or NDR?
Analyzes network sessions and application protocols, generating detailed logs for connections, DNS, HTTP, TLS, and other activity. Particularly useful for investigating unusual communication patterns and performing security forensics.
Website:
3. Suricata
Inspects network packets to detect known attack patterns, suspicious traffic, and policy violations. Best suited to security monitoring and intrusion detection rather than general-purpose traffic visualization.
Website:
4. Wireshark
Captures and inspects individual packets, allowing you to examine protocols, connection behavior, retransmissions, and communication failures. Best for troubleshooting specific problems, rather than continuous, whole-network monitoring directly on a production firewall.
Website:
5. pmacct
Collects and aggregates flow records such as NetFlow, IPFIX, and sFlow. Useful for traffic accounting, per-host or per-network usage reports, and historical analysis when the firewall or network devices export flow data.
Website:
Which should you choose?
Your goal
Best fit
Visualize traffic and bandwidth usage
ntopng
Understand detailed network communication patterns
Zeek
Detect threats and suspicious activity
Suricata
Troubleshoot individual connections and packets
Wireshark
Track traffic volume over time using flow records
pmacct
For security-focused traffic analysis, Suricata can also export detailed event logs for integration with other monitoring tools.
Deployment advice
You don't necessarily need to install every package on the firewall itself. A practical approach is to:
Run ntopng on a compatible firewall platform if you want convenient dashboards.
Export firewall logs or NetFlow/IPFIX records to a separate monitoring server.
Deploy Zeek or Suricata on a dedicated sensor receiving traffic through a network TAP or switch mirror port when deeper inspection is required.
Running packet inspection on the firewall itself can consume substantial CPU and memory, so check hardware capacity and platform compatibility before deployment.
One question that would help narrow this down: Which firewall are you using — pfSense, OPNsense, Linux (iptables/nftables), or a commercial firewall such as FortiGate or Palo Alto? I can recommend packages that fit your platform.
