🛡️ Raspberry Pi – Security Tips & Hardening (2025 Best Practices Guide)

🧲 Introduction – Secure Your Raspberry Pi from the Start

Your Raspberry Pi may be small, but it’s still a full-fledged computer—and like any Linux system connected to a network, it can be a target for attacks. Whether used as a web server, IoT controller, or remote access hub, your Pi needs proper security hardening to stay safe.

🎯 In this guide, you’ll learn:

• Key security practices for Raspberry Pi
• How to secure SSH, users, and network services
• Enable firewalls and auto-updates
• Best tools and scripts for system auditing

🔐 1. Change Default Username & Password

The default user pi is widely known. Change it or create a new user.

✅ Create a new user:

sudo adduser myuser
sudo usermod -aG sudo myuser

✅ Disable or delete pi:

sudo deluser pi

Or lock:

sudo passwd -l pi

🔑 2. Use Strong Passwords & SSH Keys

✅ Enforce strong password:

Use passwd to change user password with complexity.

✅ Use SSH Key Authentication:

ssh-keygen
ssh-copy-id pi@raspberrypi.local

Then disable password login:

sudo nano /etc/ssh/sshd_config

Set:

PasswordAuthentication no
PermitRootLogin no

Restart SSH:

sudo systemctl restart ssh

🔍 3. Enable UFW Firewall (Uncomplicated Firewall)

Install and enable UFW:

sudo apt install ufw
sudo ufw allow ssh
sudo ufw enable

Add rules for other ports/services as needed:

sudo ufw allow 80/tcp   # Web server
sudo ufw allow 443/tcp  # HTTPS

✅ Use sudo ufw status to check rules.

🛡️ 4. Keep System & Packages Updated

✅ Update regularly:

sudo apt update && sudo apt full-upgrade -y

✅ Enable unattended upgrades:

sudo apt install unattended-upgrades
sudo dpkg-reconfigure --priority=low unattended-upgrades

👁️ 5. Monitor Users & Processes

✅ List logged-in users:

who

✅ See active processes:

htop

✅ Check sudo usage logs:

sudo less /var/log/auth.log

📁 6. Secure File & Directory Permissions

✅ Review file permissions:

ls -l /home/pi

✅ Make scripts non-executable by others:

chmod 700 /home/pi/private_script.sh

✅ Avoid 777 permissions and regularly audit /etc/sudoers.

🧪 7. Disable Unused Services

Use raspi-config:

sudo raspi-config

➡️ Go to Boot Options and disable unused interfaces like:

• SPI
• I2C
• Serial
• Bluetooth

You can also check active services:

sudo systemctl list-units --type=service

🔌 8. Close Open Ports

Scan open ports:

sudo netstat -tuln

Or:

sudo ss -tuln

Disable unnecessary services:

sudo systemctl disable <service>

🧠 9. Use Fail2Ban to Block Brute Force Attacks

Install Fail2Ban:

sudo apt install fail2ban

Basic config:

sudo nano /etc/fail2ban/jail.local

Example:

[sshd]
enabled = true
port    = ssh
logpath = %(sshd_log)s
maxretry = 5

Restart:

sudo systemctl restart fail2ban

🔎 10. Audit Security with Lynis

Install Lynis:

sudo apt install lynis

Run audit:

sudo lynis audit system

✅ Get a full report on system security recommendations.

🧠 Bonus: Physical Security Tips

📌 Summary – Recap & Next Steps

Raspberry Pi may seem simple, but it can run critical systems and servers—making security a top priority. Use this guide to harden your Pi against common attacks and keep it safe whether it’s online or running locally.

🔍 Key takeaways:

• Change default credentials and enforce SSH keys
• Use UFW + Fail2Ban for port and login protection
• Regularly update and audit your system
• Disable unused services and ports to reduce attack surface

⚙️ Real-world relevance: Perfect for home servers, IoT gateways, kiosk devices, and remote systems running unattended.

❓ FAQs – Raspberry Pi Security Hardening

❓ Should I disable SSH when not in use?

✅ Yes. You can run:

sudo systemctl stop ssh

And enable it only when needed.

❓ What if I forget my SSH key and disable password login?

✅ Use a monitor + keyboard to regain access, or re-edit sshd_config via SD card reader on another system.

❓ Is a firewall necessary on Raspberry Pi?

✅ Yes, especially if it’s on a public or shared network. UFW is lightweight and effective.

❓ Can I encrypt my Raspberry Pi storage?

✅ Full-disk encryption is complex but possible. For basic use, encrypt only sensitive folders using tools like gocryptfs.

❓ How can I monitor login attempts?

✅ Use:

sudo less /var/log/auth.log

And set up Fail2Ban for automatic blocking.