NetSynth

Turn network traffic into ambient sound.

NetSynth captures live network traffic (or reads pcap files), classifies packets by protocol, and synthesizes an ambient MP3 soundscape where each traffic type produces a distinct harmonic drone. A ping sounds different from HTTPS noise, which sounds different from a port scan.

Run it, let it listen, press Ctrl+C, get an audio fingerprint of your network.

Quick Start

# Live capture on eth0 (requires root or CAP_NET_RAW)
sudo netsynth -i eth0

# Press Ctrl+C after a few seconds → saves netsynth-<timestamp>.mp3

# Sonify a pcap file (no privileges needed)
netsynth --read capture.pcap -o output.mp3

# Filter to DNS traffic only
sudo netsynth -i eth0 --filter "port 53" -o dns.mp3

# Use a custom sound config
sudo netsynth -i eth0 --config my-sounds.toml

# Print effective config as a starting template
netsynth --print-config > my-sounds.toml

Installation

Prerequisites

• Go 1.24+
• C compiler (GCC or Clang) — required for MP3 encoding (CGo)

Build from Source

git clone https://codeberg.org/gurix/yoloyolo.git
cd yoloyolo
go build -o netsynth ./cmd/netsynth

For a smaller binary:

go build -ldflags="-s -w" -o netsynth ./cmd/netsynth

Privileges

Live packet capture requires elevated privileges on Linux:

# Option A: run as root
sudo ./netsynth -i eth0

# Option B: grant capability (preferred)
sudo setcap cap_net_raw=eip ./netsynth
./netsynth -i eth0

Usage

netsynth [flags]

Flag	Description
-i, --interface	Network interface to capture on
--read	Read packets from a pcap file instead of live capture
-o, --output	Output MP3 file path (default: netsynth-<timestamp>.mp3)
--filter	BPF filter expression, tcpdump syntax (e.g. "port 53")
--config	Path to a TOML config file for custom sound mappings
--print-config	Print the full effective config as commented TOML and exit
--verbose	Print per-window protocol activity to stderr
--list-interfaces	List available network interfaces and exit

Examples

# Capture all traffic, verbose per-window output
sudo netsynth -i wlan0 --verbose

# Only HTTPS traffic
sudo netsynth -i eth0 --filter "tcp port 443" -o https.mp3

# Sonify a Wireshark capture (output derived: capture.pcap -> capture.mp3)
netsynth --read capture.pcap

# Filter a pcap file to UDP only
netsynth --read traffic.pcap --filter "udp" -o udp-only.mp3

# Use a custom sound config
sudo netsynth -i eth0 --config ~/my-sounds.toml

# Print the full effective config (great for creating a template)
netsynth --print-config > my-sounds.toml

Custom Sound Configuration

NetSynth supports TOML config files to override the default sound mappings per traffic class. You can change the frequency and waveform for any class, define your own classification rules, and inspect the effective config — all without affecting defaults you don't touch.

Config File Discovery

NetSynth looks for config files in this order (first found wins):

1. --config <path> flag (error if file does not exist)
2. ./netsynth.toml in the current working directory
3. ~/.config/netsynth/config.toml

If no config is found, NetSynth starts silently with built-in defaults.

Config File Format

# Override sound settings per traffic class.
# Only the fields you set are changed — everything else keeps its default.

[sounds.ICMP]
frequency = 80.0        # Hz (default: 65.0)
waveform = "triangle"   # sine, square, sawtooth, or triangle

[sounds.HTTPS]
frequency = 200.0

[sounds.DNS]
waveform = "square"

Available Traffic Classes

ICMP, DNS, HTTPS, HTTP, SSH, SMTP, NTP, DHCP, OtherTCP, OtherUDP, Unknown1, Unknown2, Unknown3, Unknown4

Available Waveforms

Waveform	Character
sine	Pure, clean fundamental tone
square	Hollow, buzzy (odd harmonics)
sawtooth	Bright, rich (all harmonics)
triangle	Soft, mellow (odd harmonics, fast rolloff)

All waveforms use bandlimited additive synthesis to prevent aliasing artifacts.

Custom Classification Rules

Define your own traffic classification rules using [[rules]] blocks. User-defined rules fire before built-in rules (first-match-wins):

# Match internal API traffic on port 8080
[[rules]]
protocol = "tcp"
port = 8080
class = "InternalAPI"

# Match all UDP traffic (port omitted = match any)
[[rules]]
protocol = "udp"
class = "AllUDP"

# Optionally customize the sound for your custom class
[sounds.InternalAPI]
frequency = 1500.0
waveform = "sawtooth"

Custom classes that don't have a [sounds.*] entry automatically get a unique frequency in the 1200-2350 Hz range.

Print Config

Inspect the full effective configuration (defaults merged with your overrides):

# Print defaults (useful as a starting template)
netsynth --print-config

# Print with your overrides applied
netsynth --config my-sounds.toml --print-config

# Save as a template to edit
netsynth --print-config > template.toml

The output includes (default), (override), and (auto-assigned) annotations so you can see what's customized.

Validation

• Unknown keys are rejected at startup with an error naming the bad key (catches typos like frequncy)
• Unknown class names produce a warning but do not prevent startup
• Invalid waveform values are rejected with a clear error

How It Works

NetSynth processes traffic through a four-stage pipeline:

Capture -> Classify -> Aggregate -> Synthesize -> MP3

1. Capture — Packets are read from a live interface (via go-pcap) or a pcap file. Optional BPF filtering reduces the stream to traffic of interest.

2. Classify — Each packet is matched against protocol rules (ICMP, DNS, HTTPS, SSH, HTTP, SMTP, NTP, DHCP, etc.) plus any user-defined rules from the config file. User rules fire first. Unrecognized traffic is deterministically hash-bucketed into 4 "unknown" classes so it still produces distinct sounds.

3. Aggregate — Classified packets are grouped into 500ms time windows. Each window records per-protocol packet counts that drive synthesis amplitudes.

4. Synthesize & Encode — Each traffic class maps to an oscillator at a specific frequency, waveform, and stereo position. Amplitudes rise and fall via EMA smoothing based on traffic volume. All layers are mixed and encoded to MP3 via LAME.

Sound Design

Traffic Class	Frequency	Character
ICMP (Ping)	65 Hz	Deep, distinctive ping tone
DNS	110 Hz	Quick lookup sound
HTTPS/TLS	175 Hz	Steady drone (bulk traffic)
HTTP	220 Hz	Warm web traffic hum
SSH	330 Hz	Distinct interactive tone
SMTP	440 Hz	Mail delivery tone
NTP	520 Hz	Time sync pulse
DHCP	600 Hz	Network setup sound
Other TCP	700 Hz	Generic TCP hum
Other UDP	780 Hz	Generic UDP hum
Unknown 1-4	862–1047 Hz	Dissonant, attention-grabbing

Sustained traffic sounds louder; quiet periods fade to silence. The result is a unique audio fingerprint of your network activity. All frequencies and waveforms can be overridden via the config file.

Project Structure

cmd/netsynth/   CLI entry point (Cobra)
capture/        Packet capture, BPF validation, pcap file reading
classify/       Protocol classification rules and types
aggregate/      Time-window aggregation and summary output
synth/          Oscillators, waveforms, EMA layers, stereo mixer, tone bank
config/         TOML config loading, validation, and partial merge
encode/         MP3 encoding via embedded LAME

Dependencies

Library	Purpose
gopacket/gopacket	Packet decoding
packetcap/go-pcap	Pure Go live capture (no libpcap)
sjzar/go-lame	MP3 encoding (embedded LAME C source)
spf13/cobra	CLI framework
BurntSushi/toml	TOML config parsing

No runtime dependencies beyond the compiled binary. CGo is required at build time only (for LAME).

Testing

go test ./... -v

All tests run without root privileges (capture tests use mock data and programmatically generated pcap files).

License

See LICENSE for details.