Automating Home Network Security with Python and Open Source Tools

The Problem: Security Doesn't Scale Without Automation

Digital security concept with code and lock symbols Photo by Franck on Unsplash

Requirements

To run the code examples in this post, you'll need to install the following packages:

pip install collections email ipaddress nmap requests smtplib sqlite3 subprocess vulners

Or create a requirements.txt file:

collections
email
ipaddress
nmap
requests
smtplib
sqlite3
subprocess
vulners

Managing home network security is like being a one-person SOC (Security Operations Center). You've got multiple devices, various family members with different tech literacy levels, and new threats emerging daily. Manual security management simply doesn't scale – especially when you're also trying to be present for bedtime stories.

This post shares the Python scripts and automation workflows I've developed to maintain security without sacrificing family time.

How It Works

graph TB
    subgraph "Threat Actors"
        TA1[External Attackers]
        TA2[Insider Threats]
        TA3[Supply Chain]
    end
    
    subgraph "Attack Vectors"
        AV1[Network]
        AV2[Application]
        AV3[Physical]
    end
    
    subgraph "Defenses"
        D1[Prevention]
        D2[Detection]
        D3[Response]
    end
    
    TA1 & TA2 & TA3 --> AV1 & AV2 & AV3
    AV1 & AV2 & AV3 --> D1
    D1 -->|Bypass| D2
    D2 --> D3
    
    style D1 fill:#4caf50
    style D2 fill:#ff9800
    style D3 fill:#f44336

The Foundation: Network Discovery and Asset Management

First challenge: knowing what's actually on your network. New devices appear constantly – kids' friends' phones, that new smart gadget someone bought, the mysterious device that might be the neighbor's printer.

True story: Years ago, I spent an hour hunting down an "ESP_8266_UNKNOWN" device on my network. I was ready to declare a security incident when my wife walked in: "Oh, that's probably the smart light bulb I installed in the guest bathroom."

Silence.

"You installed a what now?"

That's when I realized we needed automation – not just for security, but for marital harmony.

Automated Device Discovery

Here's the script that saves my sanity (runs hourly, alerts immediately):

#!/usr/bin/env python3
import nmap
import json
import sqlite3
from datetime import datetime
    # ... (additional implementation details)
        print(f"⚠️  Found {len(new_devices)} new devices!")
        # Send notification (covered in the notification section)

DNS Monitoring and Ad Blocking

One of the most effective security measures is controlling DNS. I use Pi-hole for ad blocking but enhanced it with security monitoring.

Detecting Suspicious DNS Queries

This script monitors DNS logs for suspicious patterns:

import re
import sqlite3
from collections import defaultdict
from datetime import datetime, timedelta

    # ... (additional implementation details)
            # Add more from threat feeds
        }

Automated Vulnerability Scanning

Keeping devices patched is crucial. This script runs weekly to identify vulnerable services:

import nmap
import vulners
import json
from datetime import datetime

    # ... (additional implementation details)
        
        return report

Smart Firewall Rules Management

Static firewall rules don't adapt to changing threats. Here's how I automate rule updates:

import subprocess
import ipaddress
from datetime import datetime, timedelta

class DynamicFirewall:
    # ... (additional implementation details)
            # Update pfBlockerNG lists
            self.update_pf_blocker_list(country_code)

Notification System

All this automation is useless if you don't know what's happening. Here's my notification system:

import smtplib
import requests
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart

    # ... (additional implementation details)
        
        self.send_email("Daily Security Summary", html_content, html=True)

Putting It All Together

The real power comes from orchestrating these scripts. Here's my master automation script:

#!/usr/bin/env python3
"""
Home Security Automation Orchestrator
Runs various security checks and responds to threats
"""
    # ... (additional implementation details)
    orchestrator = SecurityOrchestrator()
    orchestrator.run()

Lessons Learned

1. Start with Visibility

You can't secure what you can't see. Network discovery and asset management should be your first automation project.

2. Alert Fatigue is Real

Fine-tune your alerts. Too many notifications and you'll start ignoring them. I learned this the hard way when my phone wouldn't stop buzzing.

3. Family-Friendly Automation

Your security automation shouldn't impact family life. My scripts include:

Whitelisting for family devices
"Quiet hours" for non-critical alerts
Easy override mechanisms

4. Test in Isolation

Always test security automation in an isolated environment first. I once accidentally blocked my entire home network. The family was... not amused.

5. Document Everything

Future you (or your family when you're not home) needs to understand how to disable things. I maintain a simple wiki with:

What each script does
How to temporarily disable automation
Emergency contacts

Tools and Resources

Here are the key tools I use:

nmap: Network discovery and port scanning
Pi-hole: DNS filtering and logging
Dream Machine Professional: Firewall and routing
Python libraries: python-nmap, vulners, schedule
Notification: Pushover for mobile alerts

What's Next?

Security automation is an ongoing journey. My upcoming projects include:

Machine learning for anomaly detection
Automated incident response playbooks
Integration with threat intelligence feeds
Voice alerts for critical events ("Alexa, announce security alert")

Conclusion

Automating home network security has transformed my approach to protecting my family's digital life. Instead of constantly checking logs and running manual scans, I can focus on improving defenses while automation handles the routine work.

The best part? When my kids ask what I do for work, I can show them our "home security robot" in action. Nothing beats seeing their faces light up when they understand that Dad's job is basically being a cyber superhero.

Remember: the goal isn't to build Fort Knox, it's to raise the bar high enough that attackers move on to easier targets. Automation helps you maintain that bar without burning out.