How to Monitor Network Traffic with a Raspberry Pi

A Raspberry Pi can turn into a compact network monitoring appliance for a home office, workshop, or small Australian business. It can record bandwidth use, identify connected devices, show traffic patterns, and alert you when something behaves unusually.

The most practical setup uses a Raspberry Pi 4 or Pi 5, a reliable microSD card or solid-state drive, and monitoring software such as Pi-hole, ntopng, or Grafana with Prometheus. The Pi usually watches traffic through a mirrored switch port or by collecting data from a compatible router.

This approach is useful on an NBN connection when the router’s built-in statistics are too basic. It can reveal whether a smart television, security camera, cloud backup, or a work laptop is consuming the household’s upload capacity during an important video call.

The process is affordable, although performance depends on network design. A Pi connected only to an ordinary LAN port cannot automatically inspect every packet moving through the network. It needs the right capture point, sensible storage, and careful configuration to avoid creating a privacy problem.

Monitoring method	Best for	Main advantage	Main limitation
Router statistics	Basic home checks	Simple to enable	Limited history and detail
Pi-hole	DNS visibility and ad blocking	Shows requested domains	Does not inspect all traffic
ntopng	Device and bandwidth analysis	Rich traffic dashboards	Needs suitable traffic access
Port mirroring	Detailed packet monitoring	Captures selected network traffic	Requires a managed switch
Flow export	Larger home or small office networks	Efficient long-term summaries	Router or switch must support it

Choose the Raspberry Pi Hardware

A Raspberry Pi 4 with at least 2GB of memory is adequate for DNS logging and light traffic reporting. A Pi 5 provides more headroom for dashboards, databases, and multiple services. Use Ethernet rather than Wi-Fi for the monitoring device, especially if the internet connection reaches gigabit speeds.

A good power supply matters. Unstable USB power can corrupt storage and produce misleading gaps in the monitoring history. For continuous use, an SSD connected through USB 3 is preferable to a low-cost microSD card, while a small uninterruptible power supply can help during brief outages common in some regional areas.

Select Software That Matches the Goal

Pi-hole is a straightforward starting point because it records DNS requests from devices that use it as their resolver. It can show which devices contact advertising, tracking, or suspicious domains. Anyone reviewing broader home security guidance should treat DNS visibility as one layer rather than a complete security system.

For bandwidth analysis, ntopng presents hosts, protocols, traffic volumes, and historical trends in a browser dashboard. Prometheus and Grafana offer greater flexibility when you want custom graphs, while Wireshark is better for short, detailed investigations than for permanent logging.

Put the Pi in the Right Network Position

The easiest design is to place the Pi on the same LAN as the devices being monitored and use it as the network’s DNS server. This shows domain lookups, but encrypted HTTPS traffic still hides the exact pages and content. It is generally enough to identify unusual connections without collecting sensitive payloads.

For richer information, use a managed network switch with port mirroring, sometimes called SPAN. The switch copies traffic from a chosen port to the Pi’s Ethernet port. A small-business switch with this feature is more suitable than an unmanaged home switch; PoE models can also simplify camera and access-point installations, as explained in this guide to PoE switch options.

Configure Packet Capture Carefully

Install Raspberry Pi OS Lite, update it, assign a fixed local address, and enable only the services required for monitoring. If using ntopng, configure the correct interface and confirm that the dashboard receives traffic. With port mirroring, check that the mirrored port is not also being used for normal network access unless the software and switch design support that arrangement.

Do not assume every packet should be stored forever. Full packet capture quickly consumes disk space and may record private messages, passwords transmitted by poorly designed devices, or information about visitors. Flow records, DNS logs, and hourly totals usually provide useful evidence with far less exposure.

Read Traffic Patterns Instead of Isolated Spikes

A single large download does not necessarily indicate a problem. Steam updates, macOS or Windows patches, cloud photo synchronisation, and streaming services can create short bursts. Look for repeated behaviour, such as a camera uploading heavily overnight or one device contacting unfamiliar domains every few minutes.

Australian households can see unusual peaks around school holidays, when several people stream video or work remotely. On an NBN service, upload congestion can be more noticeable than download congestion, particularly when a family member sends large files or a small business runs an off-site backup during the arvo.

Account for Australian Network Conditions

Some Australian internet providers use carrier-grade NAT, which means the public address shown by a monitoring tool may be shared and inbound connections may not work as expected. This matters when interpreting external addresses or planning remote access. Check the provider’s documentation rather than assuming a traditional public IPv4 address.

Latency can also vary between Sydney, Melbourne, Brisbane, Perth, and regional locations because of routing and distance. A dashboard showing higher response times to an overseas cloud service does not automatically indicate a local fault. Compare several destinations and test the router, Wi-Fi, and NBN service separately before blaming one component.

Protect the Monitoring Appliance

Change default passwords, use SSH keys where practical, disable password login for administration, and keep Raspberry Pi OS and monitoring packages patched. The dashboard should be available only on the trusted LAN or through a properly secured VPN. Avoid exposing its web interface directly to the internet.

Limit who can view device names and browsing metadata. In a small office, tell staff what is collected and why. At home, remember that guests and family members may reasonably expect privacy. If you also manage email from an iPhone, reviewing iPhone inbox apps can help reduce notification noise while you investigate genuine network alerts.

Build a Useful Monitoring Routine

Give devices clear names, record the normal bandwidth range for each important host, and set alerts only for events that deserve attention. Examples include a new device joining the LAN, an unexpected DNS resolver, sustained upload activity, or a sudden change in a camera’s outbound destinations.

Review the dashboard weekly rather than watching it constantly. Keep short summaries for several months, remove raw logs on a defined schedule, and export only the information needed for troubleshooting or security records. A Pi monitoring system works best when it turns network activity into a small set of understandable signals: identify the device, verify the destination, check whether the behaviour is expected, and isolate it if it is not.