Rescoot Modem Service

Overview

The Rescoot Modem Service is a Go-based monitoring tool designed to track and manage cellular modem connectivity using ModemManager, with state synchronization through Redis.

It is a free and open replacement for the unu-modem service on unu's Scooter Pro.

Features

• Real-time modem state monitoring
• Retrieval of modem connectivity information
• Public and interface IP address tracking
• Signal quality and access technology reporting
• Redis-based state synchronization and pub/sub notifications

Dependencies

• ModemManager (mmcli)
• Redis
• gpsd

Building / Installing

Assuming your mdb is connected via USB Ethernet as 192.168.7.1 and aliased as mdb;

make dist
ssh root@mdb mkdir -p /etc/rescoot /etc/librescoot
scp rescoot-modem-arm-dist root@mdb:/usr/bin/rescoot-modem

Configuration

The service supports the following command-line flags:

Flag	Default Value	Description
-redis-url	redis://127.0.0.1:6379	Redis URL
-gpsd-server	localhost:2947	GPSD server address
-polling-time	5s	Polling interval for modem checks
-internet-check-time	30s	Interval for internet connectivity checks
-interface	wwan0	Network interface to monitor

Modem State Tracking

The service monitors and publishes the following modem state attributes:

• Connection status
• Public IP address
• Interface IP address
• Access technology
• Signal quality
• IMEI
• ICCID

Redis Integration

The service uses Redis to:

• Store current modem state
• Publish state change notifications on the internet channel

Redis Hash Structure

The service maintains a Redis hash internet with the following keys:

• modem-state (off, disconnected, connected, or UNKNOWN)
• ip-address (external IPv4 address or UNKNOWN)
• access-tech (access tech, depending on modem & SIM support)
  • "UNKNOWN"
  • "2G" / "GSM"
  • "3G" / "UMTS"
  • "4G" / "LTE"
  • "5G"
• signal-quality (0-100, in %, or 255 if UNKNOWN)
• sim-imei IMEI (unique hardware identifier) (this actually identifies the modem, but the name is kept for backward compatibility)
• sim-imsi IMSI (unique subscriber identity)
• sim-iccid ICCID (unique SIM card identifier)

Usage

rescoot-modem \
  -redis-url redis://redis.example.com:6379 \
  -interface wwan0 \
  -internet-check-time 45s \
  -gpsd-server localhost:2947

Error Handling

The service logs errors and attempts to maintain the most recent known state. If modem information cannot be retrieved or internet connectivity is lost, the service will update the state accordingly.