---
title: OpnSense - NTFY Integration
description: Security Notifications
published: true
date: 2026-02-23T22:00:46.462Z
tags: 
editor: markdown
dateCreated: 2026-02-23T22:00:37.268Z
---

# OPNsense ntfy Alerts

**Service:** ntfy push notifications from OPNsense
**Host:** OPNsense firewall
**ntfy Server:** Your self-hosted ntfy instance on Netgrimoire
**Methods:** CrowdSec HTTP plugin · Monit custom script · Suricata EVE watcher

---

## Overview

OPNsense does not have a built-in ntfy notification channel, but there are three distinct integration points that together provide complete coverage:

| Method | What It Alerts On | Priority |
|---|---|---|
| **CrowdSec HTTP plugin** | Every IP ban decision CrowdSec makes | 🔴 Best for threat intel alerts |
| **Monit + curl script** | System health, service failures, Suricata EVE matches, login failures | 🔴 Best for operational alerts |
| **Suricata EVE watcher** | Suricata high-severity IDS hits (via Monit watching eve.json) | 🟡 Covered via Monit |

All three use your self-hosted ntfy instance. None require external services.

---

## Prerequisites

Before starting, confirm:
- ntfy is running and reachable at `https://ntfy.netgrimoire.com` (or your internal URL)
- ntfy topic created: e.g. `opnsense-alerts`
- If ntfy has auth enabled, have a token ready
- SSH access to OPNsense as root

---

## Method 1 — CrowdSec HTTP Notification Plugin

This is the cleanest integration for security alerts. CrowdSec has a built-in HTTP notification plugin. Every time it makes a ban decision — whether from community intel, a Suricata match passed through CrowdSec, or a brute-force detection — it POSTs to ntfy.

### Step 1 — Create the HTTP notification config

SSH into OPNsense and create the ntfy config file:

```bash
ssh root@192.168.3.4
```

```bash
cat > /usr/local/etc/crowdsec/notifications/ntfy.yaml << 'EOF'
# ntfy notification plugin for CrowdSec
# CrowdSec uses its built-in HTTP plugin pointed at ntfy
type: http
name: ntfy_default

log_level: info

# ntfy accepts plain POST body as the notification message
# format is a Go template — .[]Alert is the list of alerts
format: |
  {{range .}}
  🚨 CrowdSec Decision
  Scenario: {{.Scenario}}
  Attacker IP: {{.Source.IP}}
  Country: {{.Source.Cn}}
  Action: {{.Decisions | len}} x {{(index .Decisions 0).Type}}
  Duration: {{(index .Decisions 0).Duration}}
  {{end}}

url: https://ntfy.netgrimoire.com/opnsense-alerts

method: POST

headers:
  Title: "CrowdSec Ban — OPNsense"
  Priority: "high"
  Tags: "rotating_light,shield"
  # Uncomment and set token if ntfy auth is enabled:
  # Authorization: "Bearer YOUR_NTFY_TOKEN"

# skip_tls_verify: false
EOF
```

> ⚠ Replace `https://ntfy.netgrimoire.com/opnsense-alerts` with your actual ntfy URL and topic. If ntfy is internal-only and OPNsense can reach it by hostname, the internal URL works fine.

### Step 2 — Register the plugin in profiles.yaml

Edit the CrowdSec profiles file to dispatch decisions to the ntfy plugin:

```bash
vi /usr/local/etc/crowdsec/profiles.yaml
```

Find the `notifications:` section of the default profile and add `ntfy_default`:

```yaml
name: default_ip_remediation
filters:
  - Alert.Remediation == true && Alert.GetScope() == "Ip"
decisions:
  - type: ban
    duration: 4h
notifications:
  - ntfy_default          # ← add this line
on_success: break
```

> ✓ The `ntfy_default` name must match the `name:` field in the yaml file you created above exactly.

### Step 3 — Set correct file ownership

CrowdSec rejects plugins if the configuration file is not owned by the root user and root group. Ensure the file has the right permissions:

```bash
chown root:wheel /usr/local/etc/crowdsec/notifications/ntfy.yaml
chmod 600 /usr/local/etc/crowdsec/notifications/ntfy.yaml
```

### Step 4 — Restart CrowdSec and test

```bash
# Restart via OPNsense service manager (do NOT use systemctl/service directly)
# Go to: Services → CrowdSec → Settings → Apply
# Or from shell:
pluginctl -s crowdsec restart
```

Test by sending a manual notification:

```bash
cscli notifications test ntfy_default
```

You should receive a test push on your device within a few seconds.

Then trigger a real decision to verify the full pipeline:

```bash
# Ban your own IP for 2 minutes as a test (replace with your IP)
cscli decisions add -t ban -d 2m -i 1.2.3.4
# Watch for ntfy notification
# Remove the test ban:
cscli decisions delete -i 1.2.3.4
```

---

## Method 2 — Monit + curl Script

Monit is OPNsense's built-in service monitor. It can watch processes, files, system resources, and log patterns — and call a custom shell script when a condition is met. The script fires a curl POST to ntfy.

This covers things CrowdSec doesn't — service failures, high CPU, gateway down events, SSH login failures, disk usage, and Suricata EVE alerts.

### Step 2.1 — Create the ntfy alert script

```bash
cat > /usr/local/bin/ntfy-alert.sh << 'EOF'
#!/usr/local/bin/bash
# ntfy-alert.sh — called by Monit to send ntfy push notifications
# Monit provides variables: $MONIT_HOST, $MONIT_SERVICE,
#                           $MONIT_DESCRIPTION, $MONIT_EVENT

NTFY_URL="https://ntfy.netgrimoire.com/opnsense-alerts"
# NTFY_TOKEN="Bearer YOUR_NTFY_TOKEN"  # uncomment if ntfy auth enabled

TITLE="${MONIT_HOST}: ${MONIT_SERVICE}"
MESSAGE="${MONIT_EVENT} — ${MONIT_DESCRIPTION}"

# Map Monit event types to ntfy priorities
case "$MONIT_EVENT" in
  *"does not exist"*|*"failed"*|*"error"*)
    PRIORITY="urgent"
    TAGS="rotating_light,red_circle"
    ;;
  *"changed"*|*"match"*)
    PRIORITY="high"
    TAGS="warning,yellow_circle"
    ;;
  *"recovered"*|*"succeeded"*)
    PRIORITY="default"
    TAGS="white_check_mark,green_circle"
    ;;
  *)
    PRIORITY="default"
    TAGS="bell"
    ;;
esac

curl -s \
  -H "Title: ${TITLE}" \
  -H "Priority: ${PRIORITY}" \
  -H "Tags: ${TAGS}" \
  -d "${MESSAGE}" \
  "${NTFY_URL}"

# Uncomment for auth:
# curl -s \
#   -H "Authorization: ${NTFY_TOKEN}" \
#   -H "Title: ${TITLE}" \
#   -H "Priority: ${PRIORITY}" \
#   -H "Tags: ${TAGS}" \
#   -d "${MESSAGE}" \
#   "${NTFY_URL}"
EOF

chmod +x /usr/local/bin/ntfy-alert.sh
```

### Step 2.2 — Enable Monit

Navigate to **Services → Monit → Settings → General Settings**

| Setting | Value |
|---|---|
| Enabled | ✓ |
| Polling Interval | 30 seconds |
| Start Delay | 120 seconds |
| Mail Server | Leave blank (using script instead) |

Click **Save**.

### Step 2.3 — Add Service Tests

Navigate to **Services → Monit → Service Tests Settings** and add the following tests:

**Test 1 — Custom Alert via Script**

| Field | Value |
|---|---|
| Name | `ntfy_alert` |
| Condition | `failed` |
| Action | Execute |
| Path | `/usr/local/bin/ntfy-alert.sh` |

This is the reusable action that all other tests will invoke.

**Test 2 — Suricata EVE High Alert**

| Field | Value |
|---|---|
| Name | `SuricataHighAlert` |
| Condition | `content = "\"severity\":1"` |
| Action | Execute → `/usr/local/bin/ntfy-alert.sh` |

This watches for severity 1 (highest) alerts written to the Suricata EVE JSON log.

**Test 3 — Suricata Process Down**

| Field | Value |
|---|---|
| Name | `SuricataRunning` |
| Condition | `failed` |
| Action | Execute → `/usr/local/bin/ntfy-alert.sh` |

**Test 4 — CrowdSec Process Down**

| Field | Value |
|---|---|
| Name | `CrowdSecRunning` |
| Condition | `failed` |
| Action | Execute → `/usr/local/bin/ntfy-alert.sh` |

**Test 5 — SSH Login Failure**

| Field | Value |
|---|---|
| Name | `SSHFailedLogin` |
| Condition | `content = "Failed password"` |
| Action | Execute → `/usr/local/bin/ntfy-alert.sh` |

**Test 6 — OPNsense Web UI Login Failure**

| Field | Value |
|---|---|
| Name | `WebUILoginFail` |
| Condition | `content = "webgui"` |
| Action | Execute → `/usr/local/bin/ntfy-alert.sh` |

### Step 2.4 — Add Service Monitors

Navigate to **Services → Monit → Service Settings** and add:

**Monitor 1 — Suricata EVE Log (high alerts)**

| Field | Value |
|---|---|
| Name | `SuricataEVE` |
| Type | File |
| Path | `/var/log/suricata/eve.json` |
| Tests | `SuricataHighAlert` |

**Monitor 2 — Suricata Process**

| Field | Value |
|---|---|
| Name | `Suricata` |
| Type | Process |
| PID File | `/var/run/suricata.pid` |
| Tests | `SuricataRunning` |
| Restart Method | /usr/local/etc/rc.d/suricata restart |

**Monitor 3 — CrowdSec Process**

| Field | Value |
|---|---|
| Name | `CrowdSec` |
| Type | Process |
| Match | `crowdsec` |
| Tests | `CrowdSecRunning` |

**Monitor 4 — SSH Auth Log**

| Field | Value |
|---|---|
| Name | `SSHAuth` |
| Type | File |
| Path | `/var/log/auth.log` |
| Tests | `SSHFailedLogin` |

**Monitor 5 — System Resources (optional)**

| Field | Value |
|---|---|
| Name | `System` |
| Type | System |
| Tests | `ntfy_alert` (on resource threshold exceeded) |

Click **Apply** after adding all services.

### Step 2.5 — Test Monit alerts

```bash
# Manually invoke the script to test ntfy connectivity
MONIT_HOST="OPNsense" \
MONIT_SERVICE="Test" \
MONIT_EVENT="Test alert" \
MONIT_DESCRIPTION="Testing ntfy integration from Monit" \
/usr/local/bin/ntfy-alert.sh
```

You should receive a push notification immediately.

---

## Alert Topics & Priority Mapping

Consider using separate ntfy topics to filter notifications by type on your device:

| Topic | Used For | Suggested ntfy Priority |
|---|---|---|
| `opnsense-alerts` | CrowdSec bans, Suricata high hits | high / urgent |
| `opnsense-health` | Monit service failures, process restarts | high |
| `opnsense-info` | Service recoveries, status changes | default / low |

To use separate topics, change the `NTFY_URL` in the Monit script and the `url:` in the CrowdSec config accordingly.

---

## ntfy Priority Reference

ntfy supports five priority levels that map to different notification behaviors on Android/iOS:

| ntfy Priority | Numeric | Behavior |
|---|---|---|
| `min` | 1 | No notification, no sound |
| `low` | 2 | Notification, no sound |
| `default` | 3 | Notification with sound |
| `high` | 4 | Notification with sound, bypasses DND |
| `urgent` | 5 | Phone rings through DND, repeated |

For firewall alerts: use `urgent` for process failures and `high` for IDS/ban events. Reserve `urgent` sparingly to avoid alert fatigue.

---

## Keeping Config Persistent Across Upgrades

OPNsense upgrades can overwrite files in certain paths. The safest locations for persistent custom files:

| File | Location | Persistent? |
|---|---|---|
| ntfy-alert.sh | `/usr/local/bin/ntfy-alert.sh` | ✓ Yes — not touched by upgrades |
| CrowdSec ntfy.yaml | `/usr/local/etc/crowdsec/notifications/ntfy.yaml` | ✓ Yes — plugin config directory |
| CrowdSec profiles.yaml | `/usr/local/etc/crowdsec/profiles.yaml` | ⚠ Re-check after CrowdSec updates |

After any OPNsense or CrowdSec update, verify:
```bash
# Check CrowdSec notification config is still present
ls -la /usr/local/etc/crowdsec/notifications/

# Test CrowdSec ntfy still works
cscli notifications test ntfy_default

# Check Monit script is still executable
ls -la /usr/local/bin/ntfy-alert.sh
```

---

## Troubleshooting

**No notification received from CrowdSec test:**

```bash
# Check CrowdSec logs for plugin errors
tail -50 /var/log/crowdsec.log | grep -i ntfy
tail -50 /var/log/crowdsec.log | grep -i notification

# Verify ntfy URL is reachable from OPNsense
curl -v -d "test" https://ntfy.netgrimoire.com/opnsense-alerts

# Check profiles.yaml has ntfy_default in notifications section
grep -A5 "notifications:" /usr/local/etc/crowdsec/profiles.yaml
```

**No notification received from Monit:**

```bash
# Run the script manually with test variables
MONIT_HOST="test" MONIT_SERVICE="test" \
MONIT_EVENT="test" MONIT_DESCRIPTION="test message" \
/usr/local/bin/ntfy-alert.sh

# Check Monit is running
ps aux | grep monit

# Check Monit logs
tail -50 /var/log/monit.log
```

**CrowdSec plugin ownership error:**

```bash
# Fix ownership if CrowdSec refuses to load the plugin
chown root:wheel /usr/local/etc/crowdsec/notifications/ntfy.yaml
ls -la /usr/local/etc/crowdsec/notifications/
```

**ntfy auth failing:**

```bash
# Test with token manually
curl -H "Authorization: Bearer YOUR_TOKEN" \
     -H "Title: Test" \
     -d "Auth test" \
     https://ntfy.netgrimoire.com/opnsense-alerts
```

---

## Related Documentation

- [OPNsense Firewall](./opnsense-firewall) — parent firewall documentation
- [CrowdSec](./crowdsec) — threat intelligence engine sending these alerts
- [Suricata IDS/IPS](./suricata-ids-ips) — source of EVE alerts watched by Monit
- [ntfy](./ntfy) — self-hosted notification server on Netgrimoire
