unRAID Script for ProtonVPN / qBittorent (u/the-ephus)

#!/bin/bash

# CONFIGURATION
CONTAINER="qbittorrent" # exact name of the torrent container in unRAID
LISTENING_PORT="6881" # port that the torrent software is expecting to listen on for P2P connections (found in webUI settings)
WGTUNNEL="10.2.0.1" # Local tunnel network pool (change last number to 1). Provided in VPN provider's Wireguard configuration.
LOGFILE="/var/log/natpmp_forward.log" # where the script logs will be stored - this script will create the file if needed. /var/log directory is stored in RAM and will not persist on reboot.
LOG_RETENTION_DAY=3 # how often (in days) the log file is purged and a new one created
INTERVAL=45 # How often this script loops, in seconds. Some VPN providers will only reserve a port for 60 seconds.

if ! docker exec "$CONTAINER" which natpmpc &>/dev/null; then
    echo "natpmpc not found in container '$CONTAINER'. Exiting." >&2
    exit 1
fi

while true; do
    mkdir -p "$(dirname "$LOGFILE")"

    # Rotate log if older than retention period
    if [[ -f "$LOGFILE" ]]; then
        FILE_AGE_DAYS=$(( ( $(date +%s) - $(stat -c %Y "$LOGFILE") ) / 86400 ))
      if (( FILE_AGE_DAYS >= LOG_RETENTION_DAY )); then
          rm -f "$LOGFILE"
      fi
    fi

    DATE_LINE="===== $(date) ====="
    echo "$DATE_LINE"
    echo "$DATE_LINE" >> "$LOGFILE"

    # Check if container is running
    if ! docker inspect -f '{{.State.Running}}' "$CONTAINER" 2>/dev/null | grep -q true; then
        echo "Container '$CONTAINER' is NOT running." | tee -a "$LOGFILE"
        sleep "$INTERVAL"
        continue
    fi

    # Run natpmpc for TCP
    TCP_OUTPUT=$(docker exec "$CONTAINER" natpmpc -a 0 "$LISTENING_PORT" tcp 1200 -g "$WGTUNNEL" 2>&1)
    echo "TCP Mapping Output:" >> "$LOGFILE"
    echo "$TCP_OUTPUT" >> "$LOGFILE"
    echo "" >> "$LOGFILE"

    # Run natpmpc for UDP
    UDP_OUTPUT=$(docker exec "$CONTAINER" natpmpc -a 0 "$LISTENING_PORT" udp 1200 -g "$WGTUNNEL" 2>&1)
    echo "UDP Mapping Output:" >> "$LOGFILE"
    echo "$UDP_OUTPUT" >> "$LOGFILE"
    echo "" >> "$LOGFILE"

    # Extract mapped port
    MAPPED_PORT=$(echo "$UDP_OUTPUT" | grep -oP 'Mapped public port \K[0-9]+' | tail -n1)

     if [[ -z "$MAPPED_PORT" || ! "$MAPPED_PORT" =~ ^[0-9]+$ ]]; then
        echo "Failed to map port or retrieve mapped port. Check natpmpc output above." | tee -a "$LOGFILE"
        echo "" >> "$LOGFILE"
    else
        echo "VPN port mapped successfully: $MAPPED_PORT to $LISTENING_PORT" | tee -a "$LOGFILE"
        echo "" >> "$LOGFILE"
    fi

    sleep "$INTERVAL"
done