Lopa

Lopa is a lightweight, centralized network quality measurement and monitoring tool written in Go. It provides active probes (ICMP/TCP/UDP/TWAMP-light), passive interface statistics, and netlink-based monitoring (interface, IP, route changes), with a unified REST API and CLI.

Architecture

• lopad — Daemon: runs the measurement engine, HTTP API, optional reflector (UDP echo + TWAMP-light), and netlink monitor. Start this first on each measurement node.
• lopa — CLI client: talks to lopad via HTTP to create tasks, list/show/stop/delete them, and manage monitors.

The CLI uses http://127.0.0.1:8080 by default; set LOPA_DAEMON_ADDR or use --daemon to point to another lopad.

Features

Active measurement (ping, tcp, udp, twamp)

• Ping — ICMP latency, loss, jitter.
• TCP — TCP connect (TCPing) to a host:port.
• UDP — UDP probe to a reflector (echo); measures RTT/loss/jitter.
• TWAMP — TWAMP-light client to a standard Session-Reflector (e.g. port 862).

Modes: count (N packets), duration (run for T seconds), continuous (until stopped, with sliding-window stats).
In continuous mode you can set loss/latency thresholds and an alert webhook; recovery notifications are also sent.

Passive measurement

• Sample interface counters (bytes/packets in and out, errors, drops) at an interval.
• Modes: duration or continuous. No probe traffic.

Monitor (netlink, Linux)

• Interface — Link up/down, name/MTU changes.
• IP — Address add/delete on interfaces.
• Route — Route add/delete (optional filter by table or destination CIDR).

Events can be stored in memory and sent to a webhook URL per task.

Reflector (built into lopad)

• Generic UDP echo (default :8081) for UDP probe.
• TWAMP-light Session-Reflector (default :862) for TWAMP-light.
  Disable with --no-reflector or config.

Build

# CLI client (talks to daemon)
go build -o lopa ./cmd/lopa

# Daemon (measurement engine + API + reflector + monitor)
go build -o lopad ./cmd/lopad

Run

# 1. Start the daemon (e.g. on the measurement node)
./lopad
# Optional: --no-reflector, --no-monitor
# Config via env: LOPA_HTTP_ADDR, LOPA_LOG_LEVEL, etc.

# 2. Use the CLI (default daemon: http://127.0.0.1:8080)
./lopa --help
./lopa ping 192.168.1.1 --mode count --count 4
./lopa tcp example.com:443
./lopa udp reflector-host:8081 --mode duration --duration 30s
./lopa twamp reflector-host:862
./lopa passive eth0 --mode duration --duration 1m
./lopa task list
./lopa task show <task-id>
./lopa monitor add --type interface --interface eth0 --webhook-url http://localhost:9999/hook
./lopa monitor add --type route --route-dst 0.0.0.0/0
./lopa monitor list
./lopa monitor events <monitor-id>

API (HTTP)

Base path: /api/v1.

Method	Path	Description
POST	/tasks/ping, /tasks/tcp, /tasks/udp, /tasks/twamp, /tasks/passive	Create measurement task
GET	/tasks	List all tasks
GET	/tasks/:id	Get task result
POST	/tasks/:id/stop	Stop task
DELETE	/tasks/:id	Delete task
POST	/monitors	Create monitor task
GET	/monitors	List monitors
GET	/monitors/:id	Get monitor
PATCH	/monitors/:id	Update monitor
DELETE	/monitors/:id	Delete monitor
GET	/monitors/:id/events?last=N	Get recent events

Configuration

lopad uses Viper: config file, environment variables (LOPA_*), or defaults.

Key	Default	Description
http.addr	:8080	HTTP API listen address
log.level	info	Log level
reflector.enabled	true	Enable reflector
reflector.addr	:8081	UDP echo listen address
reflector.twamp_addr	:862	TWAMP-light reflector; empty to disable
monitor.enabled	true	Enable netlink monitor
monitor.event_buffer_size	100	Max events per monitor task

License

See repository. This project is under active development.