Building a Flipper Zero Ethernet Adapter for Red Team Recon

Physical access to a network jack is often overlooked in internal security audits. But when red teams or attackers gain access to a live Ethernet port, they can quickly determine whether a system is vulnerable — especially if they have a stealthy tool in hand.

In this project, I transformed a Flipper Zero into a compact Ethernet reconnaissance device using a W5500 module and the Flipper protoboard. The final setup lets me plug into any wall port or switch and instantly verify:

• If the port is live
• Whether DHCP is available
• If there’s basic Layer 3 network access (pinging gateways or public IPs)
• Whether the port is on an isolated VLAN or internal network

This build is fast to deploy, minimally invasive, and easy to conceal — making it ideal for red team operations, network diagnostics, or security testing in enterprise environments.

Objectives

By the end of this guide, I will have:

• Soldered a W5500 Ethernet module onto a Flipper Zero protoboard
• Installed the Flipper W5500 app
• Verified DHCP IP assignment, ping response, and gateway reachability
• Evaluated how this setup supports red team objectives and internal network assessments

What is the W5500 Ethernet Module?

The W5500 is a hardwired Ethernet controller with a built-in TCP/IP stack. It communicates over SPI, making it compatible with many microcontrollers — including the Flipper Zero.

Key Specs:

• Supports 10/100 Mbps Ethernet
• Has native support for DHCP, UDP, TCP, and ARP

In this project, the W5500 is responsible for establishing the physical and data link layers, while the Flipper handles interface logic via its custom app.

What is the Flipper Protoboard?

The Flipper protoboard is a GPIO breakout accessory for the Flipper Zero that allows custom hardware mods. It connects to the Flipper via the GPIO header and exposes pins for SPI, UART, I2C, and power.

I used it to mount and wire the W5500 module securely, using standard header pins and jumper wires to maintain modularity.

Step 1: Soldering the W5500 Module

I used a standard W5500 breakout board with an onboard RJ45 Ethernet jack. This board exposes the SPI pins necessary for communication and includes onboard voltage regulation for compatibility with either 3.3V or 5V input. To connect it to the Flipper Zero, I used the official protoboard, which provides easy access to the Flipper’s GPIO header.

Here’s how I mapped the pins:

Notes:

• I confirmed the specific version of my W5500 module could operate at 3.3V, which matches the Flipper’s logic level. 
• Applied a flux to ensure each solder joint was solid and oxidation-free.

The end result was a clean, stable connection between the Flipper and the W5500 — durable enough to be moved around during testing without breaking or wobbling.

Step 2: Installing the Flipper W5500 App

The Flipper W5500 app enables basic Ethernet support through SPI. It communicates with the W5500 driver, configures the module, and presents a simple interface for IP configuration and testing. Just find the app in the app store under, “W5500 Ethernet.”

Here’s what the app supports out of the box:

• DHCP IP acquisition — auto-assigns an IP from the network
• Static IP config — can be used in segmented networks
• ICMP pings — test reachability of a host (local or remote)
• Basic diagnostics — shows link state and IP info

If successful, the app displays:

• Assigned IP address
• Gateway
• Subnet mask

It also includes a ping test tool, allowing you to verify network connectivity directly from the device.

Step 3: Live Testing with a Router

Once the Flipper W5500 app was installed, I connected the Flipper + W5500 module to a known-good Ethernet port on a standard consumer router to validate core functionality: DHCP and basic network reachability.

Test Environment:

• Router: default settings, DHCP enabled (192.168.1.0/24 subnet)
• Flipper connected directly to a LAN port via Ethernet cable
• Network had internet access, but no DNS resolution was needed for testing

What I tested:

DHCP Lease Acquisition

• Launched the W5500 app on the Flipper
• Plugged into the LAN port
• The app automatically requested an IP via DHCP
• Flipper displayed a valid IP (e.g., 192.168.1.162) with subnet and gateway

This confirmed the Flipper could negotiate a lease with a standard DHCP server and was logically part of the network.

Gateway Ping

• Used the app’s built-in ICMP ping function to target the default gateway (192.168.1.1)
• All packets returned successfully with low latency

This verified Layer 3 connectivity inside the LAN.

External IP Ping

• Sent pings to 8.8.8.8 (Google)
• Responses confirmed that the Flipper had outbound access to the internet
• DNS wasn’t required for this test since it used a raw IP address

Red Teaming and Enterprise Implications

Even though this project involved just a few wires and a simple app, the end result is a functional Ethernet recon tool — one that’s small, silent, and ideal for on-site testing. Here’s how this setup fits into red teaming and enterprise assessment workflows:

Red Team Use Cases

• Live Port Identification  In physical engagements, this tool can be plugged into any wall jack to quickly determine if the port is active and routable. If the Flipper receives a DHCP lease and can ping the gateway or external IPs, the port is live and has internet access — a critical piece of intel when assessing how secure or segmented a physical network is.
• Low-Profile Recon  Compared to using a laptop or Raspberry Pi, the Flipper draws far less attention. It’s small enough to fit in a pocket and can be deployed in under 10 seconds. No boot time, no keyboard or monitor required. Ideal for fast tests in lobbies, conference rooms, or under desks where unmonitored ports are often left live.
• Test Without Triggering Alerts  This method doesn’t rely on active scanning or traffic generation. It passively requests a DHCP lease and runs ICMP pings — both actions that often go unnoticed in default logging configurations. This makes it useful for initial low-noise probing before launching more active enumeration tools.

Enterprise Security Takeaways

• Port Security Gaps  If the Flipper receives an IP and confirms outbound access, it means the port isn’t locked down with 802.1X, MAC filtering, or VLAN isolation. That’s a signal for defenders that physical layer access controls are missing or misconfigured.
• DHCP and Network Monitoring Blind Spots  Networks that don’t alert on unknown MAC addresses receiving DHCP leases are vulnerable to exactly this type of tool. Enterprise NAC and logging systems should be able to detect and respond to unauthorized DHCP requests — especially from hardware not on an allow list.
• Compliance Implications  Regulatory frameworks often require that physical ports in sensitive areas be disabled or monitored. Running this tool against unused jacks can validate whether policies are actually enforced in practice — something that often gets missed in checkbox-based audits.

Conclusion

By combining a W5500 Ethernet module with the Flipper Zero protoboard and a simple app, I built a compact, functional Ethernet testing tool. It reliably detects live ports, confirms DHCP availability, and performs basic connectivity checks — all from a device that fits in the palm of your hand.

This build is a valuable addition to a red team toolkit. It’s quick to deploy, hard to spot, and capable of silently confirming internal network exposure without triggering alarms. Whether used for reconnaissance during a physical engagement or to verify security controls in an enterprise environment, this tool does one thing very well: tell you if a network is accessible — and it does it fast.

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