Frequently Asked Questions¶

Common questions about Espilon.

General¶

What is Espilon?

Espilon is an ESP32-based embedded agent framework for security research. It allows ESP32 microcontrollers to act as networked agents controlled via a C2 (Command & Control) server.

Is Espilon legal to use?

Espilon is a security research tool. It is legal to use for:

Authorized penetration testing
Security research in controlled environments
CTF competitions
Educational purposes

Unauthorized use is illegal. Always obtain written permission before deployment.

What can I do with Espilon?

Espilon agents can:

Scan networks (ARP, ICMP)
Create fake access points
Capture images (ESP32-CAM)
Proxy network traffic
Monitor wireless activity
And more with custom modules

Which ESP32 boards are supported?

Supported boards include:

ESP32 DevKit (any variant)
LilyGO T-Call (for GPRS)
ESP32-CAM (for camera features)
NodeMCU-32S
Most ESP32 boards with 4MB+ flash

Hardware¶

Which board should I buy?

Depends on your use case:

Use Case	Recommended Board
General WiFi	ESP32 DevKit
GPRS/Cellular	LilyGO T-Call
Camera/Vision	ESP32-CAM
Development	NodeMCU-32S

Does ESP32 support 5GHz WiFi?

No. The ESP32 only supports 2.4GHz WiFi (802.11 b/g/n). This is a hardware limitation.

How long does battery last?

Typical battery life with 1500mAh Li-Po:

Mode	Runtime
Idle (connected)	10-14 hours
Active commands	6-10 hours
Streaming	3-5 hours
Deep sleep	100+ hours

Can I use external antenna?

Yes, for boards with U.FL/IPEX connector:

LilyGO T-Call: Yes (GSM antenna included)
ESP32-CAM: Some variants
ESP32 DevKit: Rarely (most have PCB antenna)

Software¶

Which ESP-IDF version is required?

Espilon requires ESP-IDF v5.3.2 or compatible version. Using other versions may cause build errors.

Can I use Arduino instead of ESP-IDF?

Espilon is built with ESP-IDF, not Arduino. While ESP-IDF is more complex, it provides:

Better performance
Lower-level access
More features
Production-ready stability

How do I update the firmware?

cd espilon_bot
git pull
idf.py build
idf.py -p /dev/ttyUSB0 flash

Can I add custom modules?

Yes! See the Module Development Guide for creating custom modules. Basic structure:

Create module in components/modules/
Register commands in command registry
Enable in menuconfig
Build and flash

Connectivity¶

WiFi or GPRS - which should I use?

Factor	WiFi	GPRS
Range	50-100m	Nationwide
Speed	Fast	Slow (~50Kbps)
Cost	Free	SIM + data plan
Latency	Low	Medium
Setup	Easy	Moderate

Use WiFi for local deployments. Use GPRS for remote/mobile.

Can I use both WiFi and GPRS?

Not simultaneously. You must choose one network backend at compile time. However, you can have multiple agents with different backends.

What encryption is used?

All C2 communication uses ChaCha20 stream cipher with:

256-bit key (32 bytes)
96-bit nonce (12 bytes)
Per-message encryption

Can the C2 traffic be detected?

The traffic is encrypted but not hidden. Network monitoring can detect:

Connection to C2 IP/port
Traffic patterns
Data volume

For stealth, use VPN or tunneling.

C2 Server¶

Can C2 run on Windows?

Yes, via WSL2 (Windows Subsystem for Linux). Native Windows support is not tested.

How many agents can connect?

Default: 100 concurrent connections. Adjustable in config. Practical limit depends on:

Server resources
Network bandwidth
Command frequency

Can I control agents from mobile?

Not directly. C3PO is a CLI application. Options:

SSH to C2 server from mobile
Build a web interface (community contribution)
Use remote desktop

Is there a web interface?

Not built-in. C3PO is CLI-only. A web interface could be built using the Python API.

Troubleshooting¶

Why won't my device flash?

Common causes:

Not in download mode: Hold BOOT, press RESET
Wrong port: Check with ls /dev/ttyUSB*
Permission denied: Add user to dialout group
Bad cable: Use data-capable USB cable

Why does my device keep rebooting?

Common causes:

Power issue: Use better power supply
Brownout: Add capacitor or reduce load
Code crash: Check serial monitor for errors
Watchdog: Increase timeout or fix blocking code

Why is my connection unstable?

Check:

Power supply stability
WiFi signal strength
Network congestion
C2 server resources
Encryption key match

How do I factory reset?

# Erase everything
idf.py -p /dev/ttyUSB0 erase_flash

# Reflash
idf.py -p /dev/ttyUSB0 flash

Security¶

Is the communication secure?

Yes, all C2 traffic is encrypted with ChaCha20. However:

Keys must be kept secret
Compromised keys = compromised security
Traffic patterns may be analyzed

Can agents be hijacked?

With proper security:

Encryption prevents interception
Unique keys per deployment
No known vulnerabilities in protocol

Without proper security:

Default keys are public
Unencrypted = fully exposed

What about physical security?

ESP32 has limited physical security:

Flash can be read without encryption
JTAG debug possible on some boards
Physical access = potential compromise

For sensitive deployments, enable flash encryption.

Contributing¶

How can I contribute?

Contributions welcome:

Fork the repository
Create feature branch
Make changes
Submit pull request

Areas needing help:

Documentation improvements
New modules
Bug fixes
Testing

Where do I report bugs?

GitHub Issues

Include:

ESP-IDF version
Board type
Error messages
Steps to reproduce

Is there a community?

GitHub Discussions: Q&A and ideas
Issues: Bug reports and features
Documentation: This site

See also: Troubleshooting | Getting Started