108 lines
4.8 KiB
Markdown
108 lines
4.8 KiB
Markdown
# NetSynth
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## What This Is
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A Go CLI tool that captures live network traffic on an interface, classifies packets by protocol, and synthesizes an ambient MP3 soundscape where each traffic type produces a distinct harmonic drone or tone. Supports live capture with BPF filtering and offline pcap file sonification.
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## Core Value
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Network traffic patterns are instantly recognizable as distinct sounds — a ping sounds different from HTTPS noise, which sounds different from a port scan.
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## Current State
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**v1.0 MVP shipped 2026-03-26.** 3,254 lines of Go across 6 packages.
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Tech stack: gopacket/gopacket v1.5.0, packetcap/go-pcap (pure Go capture), sjzar/go-lame v0.0.9 (embedded LAME), spf13/cobra v1.10.2.
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All 16 v1 requirements validated. Full pipeline working: capture -> classify -> aggregate -> synthesize -> MP3.
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**Phase 5 complete 2026-03-26:** Waveform types (sine, square, sawtooth, triangle) with bandlimited synthesis added. OscillatorBank decoupled from global config — NewBank now accepts injected config maps with dynamic gain scaling.
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## Requirements
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### Validated (v1.0)
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- Capture live packets from a specified network interface until Ctrl+C
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- Classify packets by known protocols (ICMP, DNS, HTTPS, SSH, etc.) with 12 predefined rules
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- Auto-cluster unrecognized traffic into 4 hash-bucketed unknown classes with distinct tones
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- Aggregate traffic into 500ms time windows driving amplitude evolution
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- End-to-end pipeline: capture -> classify -> synthesize -> MP3 output
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- Map each traffic class to a distinct ambient/drone layer (sine oscillators + EMA smoothing)
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- Stereo mixing with constant-power panning, no distortion
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- MP3 encoding via embedded LAME, zero-packet guard
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- CLI with `-i`, `-o`, `--list-interfaces`, `--verbose`, `--filter`, `--read` flags
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- BPF capture filter for scoping live traffic
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- Offline pcap file sonification with timestamp-based windowing
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### Active
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(See REQUIREMENTS.md for v1.1 requirements)
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### Out of Scope
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- Real-time audio playback — file output only
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- GUI or web interface — CLI only
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- Rhythmic/percussive output — ambient/drone style only
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- Stereo position configuration — v1.1 focuses on frequency, waveform, and custom rules
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## Context
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- Built in Go (CGO_ENABLED=1 for LAME), single binary output
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- Packet capture requires root/CAP_NET_RAW on Linux
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- Pure Go capture layer (no libpcap dependency)
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- MP3 encoding embeds LAME C source (no system library needed)
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- 14 traffic classes: 10 known protocols + 4 hash-bucketed unknowns
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## Constraints
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- **Language**: Go — user preference, single binary output
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- **Privileges**: Packet capture requires root/CAP_NET_RAW on Linux
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- **Audio format**: MP3 output (not WAV or raw PCM)
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- **Interaction model**: Non-interactive capture (run -> Ctrl+C -> file saved)
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## Key Decisions
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| Decision | Rationale | Outcome |
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| Go over Python/Rust | User preference, single binary, good perf | Good |
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| Ambient/drone style | Layered tones better represent continuous traffic patterns | Good |
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| Predefined + auto-cluster | Known protocols get recognizable sounds; unknown traffic still represented | Good |
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| File output only | Simpler v1, avoids real-time audio complexity | Good |
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| go-pcap over libpcap | Pure Go, no CGo for capture, cross-compilation friendly | Good |
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| go-lame (embedded C) over shine-mp3 | Better quality, smaller files, acceptable CGo tradeoff | Good |
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| Hand-rolled synthesis over audio libraries | 20 lines of oscillator code, no unnecessary dependencies | Good |
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| Hash-bucketed unknowns over k-means | Deterministic, zero-config, sufficient for v1 audio distinction | Good |
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| Ordered []Rule classifier over switch | Configurable, extensible, first-match-wins semantics | Good |
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| 500ms window duration | Balances temporal resolution against snapshot frequency for synthesis | Good |
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## Current Milestone: v1.1 Custom Sound Mappings
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**Goal:** Users can customize how traffic sounds via a TOML config file
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**Target features:**
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- Custom frequency per traffic class (override built-in Hz values)
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- Custom waveform per class (sine, square, sawtooth, triangle)
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- User-defined classification rules with custom sounds
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- Auto-discover config from ./netsynth.toml or ~/.config/netsynth/config.toml
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- --config flag for explicit config path
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## Evolution
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This document evolves at phase transitions and milestone boundaries.
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**After each phase transition:**
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1. Requirements invalidated? -> Move to Out of Scope with reason
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2. Requirements validated? -> Move to Validated with phase reference
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3. New requirements emerged? -> Add to Active
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4. Decisions to log? -> Add to Key Decisions
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5. "What This Is" still accurate? -> Update if drifted
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**After each milestone:**
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1. Full review of all sections
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2. Core Value check — still the right priority?
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3. Audit Out of Scope — reasons still valid?
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4. Update Context with current state
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---
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*Last updated: 2026-03-26 after v1.1 milestone start*
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