Internet outage notifications

Paradox: if the internet at home goes down, a notification web service won’t be able to send anything. The solution is to send from a different device: a NAS, a Raspberry Pi with an LTE modem, or a work laptop with an active mobile connection.

What we’ll do

1. On an independent device (with its own fallback channel — an LTE/4G dongle, mobile hotspot) we’ll run the script-watchdog.
2. It tries every minute to reach the home server/router and an external host (for example, 1.1.1.1).
3. On state transitions it sends to Notifly.

Script notifly-net-check

/usr/local/bin/notifly-net-check

#!/usr/bin/env bash
set -eu
set -a; source /etc/notifly.env; set +a

HOME_HOST="192.168.1.1"     # home router
WAN_HOST="1.1.1.1"          # external host
STATE=/var/lib/notifly-net.state

ping_ok() { ping -c1 -W2 "$1" >/dev/null 2>&1; }

if   ping_ok "$WAN_HOST" && ping_ok "$HOME_HOST"; then NOW=ALL_OK
elif ping_ok "$WAN_HOST" && ! ping_ok "$HOME_HOST"; then NOW=HOME_DOWN
elif ! ping_ok "$WAN_HOST" && ping_ok "$HOME_HOST"; then NOW=WAN_DOWN
else NOW=ALL_DOWN
fi

PREV=$(cat "$STATE" 2>/dev/null || echo ALL_OK)
if [[ "$NOW" != "$PREV" ]]; then
    case "$NOW" in
        ALL_OK)    TITLE="✅ Интернет восстановлен"; PRI=4 ;;
        WAN_DOWN)  TITLE="⚠️ Нет внешнего интернета"; PRI=7 ;;
        HOME_DOWN) TITLE="⚠️ Дом не отвечает";        PRI=8 ;;
        ALL_DOWN)  TITLE="🔥 Всё лежит";              PRI=10 ;;
    esac
    curl -fsS -X POST "$NOTIFLY_URL/message?token=$NOTIFLY_TOKEN" \
        -H "Content-Type: application/json" \
        -d "$(jq -n --arg t "$TITLE" \
                  --arg m "Состояние: $NOW (было $PREV)" \
                  --argjson p "$PRI" \
                  '{title:$t, message:$m, priority:$p}')" >/dev/null
fi
echo "$NOW" > "$STATE"

Cron every minute:

* * * * * /usr/local/bin/notifly-net-check

Important

This device must not access the internet via the same channel that it checks. Otherwise, when the channel fails the push will go nowhere. Ideally — a Raspberry Pi / OpenWRT router with a backup LTE SIM.

Alternative: checking from a phone or laptop

If you don’t have a separate device, you can set up the watchdog on a work laptop — it is almost always connected to a mobile hotspot:

# checks the home router and sends a push if it's silent for five consecutive minutes
COUNT=0
while true; do
    if ping -c1 -W2 home.duckdns.org >/dev/null 2>&1; then
        COUNT=0
    else
        COUNT=$((COUNT+1))
        if (( COUNT == 5 )); then
            notifly-send "⚠️ Дом не пингуется 5 минут" "" 7
        fi
    fi
    sleep 60
done

Windows: PowerShell + Test-Connection

If the watchdog is a work Windows laptop with mobile internet. Assumes the function Send-Notifly is configured.

C:\scripts\Notifly-Net-Check.ps1

. $env:USERPROFILE\Documents\WindowsPowerShell\Notifly.ps1

$HomeHost = "192.168.1.1"
$WanHost  = "1.1.1.1"
$State    = "$env:LOCALAPPDATA\notifly-net.state"

function Ping-Ok($h) {
    return Test-Connection -ComputerName $h -Count 1 -Quiet -TimeoutSeconds 2
}

$wanOk  = Ping-Ok $WanHost
$homeOk = Ping-Ok $HomeHost

$now = if     ($wanOk -and $homeOk)  { "ALL_OK" }
       elseif ($wanOk -and -not $homeOk) { "HOME_DOWN" }
       elseif (-not $wanOk -and $homeOk) { "WAN_DOWN" }
       else                              { "ALL_DOWN" }

$prev = if (Test-Path $State) { Get-Content $State -Raw } else { "ALL_OK" }
$prev = $prev.Trim()

if ($now -ne $prev) {
    $info = switch ($now) {
        "ALL_OK"    { @{ Title = "✅ Интернет восстановлен";       Pri = 4 } }
        "WAN_DOWN"  { @{ Title = "⚠️ Нет внешнего интернета";    Pri = 7 } }
        "HOME_DOWN" { @{ Title = "⚠️ Дом не отвечает";          Pri = 8 } }
        "ALL_DOWN"  { @{ Title = "🔥 Всё лежит";                  Pri = 10 } }
    }
    Send-Notifly -Title $info.Title -Message "Состояние: $now (было $prev)" -Priority $info.Pri
}
$now | Set-Content $State

Schedule to run every minute:

$Action  = New-ScheduledTaskAction -Execute "powershell.exe" `
    -Argument "-NoProfile -WindowStyle Hidden -ExecutionPolicy Bypass -File C:\scripts\Notifly-Net-Check.ps1"
$Trigger = New-ScheduledTaskTrigger -Once -At (Get-Date) `
    -RepetitionInterval (New-TimeSpan -Minutes 1)
Register-ScheduledTask -TaskName "Notifly Net Check" -Action $Action -Trigger $Trigger

Benefits

• You’ll find out about an outage before you notice quiet social media.
• Especially valuable for a home server / NAS: you’re out of town, the power at home went out, the NAS is already offline — and you received a push immediately.
• Can be integrated with a UPS: when switching to battery send a message estimating “time until shutdown.”

What to improve next

• Integrate a UPS daemon (apcupsd, nut) — push on switching to battery.
• Attach mtr output to the problematic node.