Unbound Installation Guide Installation Guide

Unbound is a free and open-source DNS Resolver. A validating, recursive, and caching DNS resolver

Hardware Requirements:

CPU: 2 cores minimum (4+ cores recommended)

RAM: 2GB minimum (4GB+ recommended)

Storage: 1GB for installation

Network: 53 ports

Operating System:

Linux: Any modern distribution (RHEL, Debian, Ubuntu, CentOS, Fedora, Arch, Alpine, openSUSE)

macOS: 10.14+ (Mojave or newer)

Windows: Windows Server 2016+ or Windows 10

FreeBSD: 11.0+

Network Requirements:

Port 53 (default unbound port)

Dependencies:

unbound-anchor, unbound-control

System Access: root or sudo privileges required

This guide supports installation on:

RHEL 8/9 and derivatives (CentOS Stream, Rocky Linux, AlmaLinux)

Debian 11/12

Ubuntu 20.04/22.04/24.04 LTS

Arch Linux (rolling release)

Alpine Linux 3.18+

openSUSE Leap 15.5+ / Tumbleweed

SUSE Linux Enterprise Server (SLES) 15+

macOS 12+ (Monterey and later)

FreeBSD 13+

Windows 10/11/Server 2019+ (where applicable)

bash

# Install EPEL repository if needed
sudo dnf install -y epel-release

# Install unbound
sudo dnf install -y unbound unbound-anchor, unbound-control

# Enable and start service
sudo systemctl enable --now unbound

# Configure firewall
sudo firewall-cmd --permanent --add-service=unbound
sudo firewall-cmd --reload

# Verify installation
unbound --version || systemctl status unbound

bash

# Update package index
sudo apt update

# Install unbound
sudo apt install -y unbound unbound-anchor, unbound-control

# Enable and start service
sudo systemctl enable --now unbound

# Configure firewall
sudo ufw allow 53

# Verify installation
unbound --version || systemctl status unbound

bash

# Install unbound
sudo pacman -S unbound

# Enable and start service
sudo systemctl enable --now unbound

# Verify installation
unbound --version || systemctl status unbound

bash

# Install unbound
apk add --no-cache unbound

# Enable and start service
rc-update add unbound default
rc-service unbound start

# Verify installation
unbound --version || rc-service unbound status

bash

# Install unbound
sudo zypper install -y unbound unbound-anchor, unbound-control

# Enable and start service
sudo systemctl enable --now unbound

# Configure firewall
sudo firewall-cmd --permanent --add-service=unbound
sudo firewall-cmd --reload

# Verify installation
unbound --version || systemctl status unbound

bash

# Using Homebrew
brew install unbound

# Start service
brew services start unbound

# Verify installation
unbound --version

bash

# Using pkg
pkg install unbound

# Enable in rc.conf
echo 'unbound_enable="YES"' >> /etc/rc.conf

# Start service
service unbound start

# Verify installation
unbound --version || service unbound status

powershell

# Using Chocolatey
choco install unbound

# Or using Scoop
scoop install unbound

# Verify installation
unbound --version

bash

# Create configuration directory if needed
sudo mkdir -p /etc/unbound

# Set up basic configuration
sudo tee /etc/unbound/unbound.conf << 'EOF'
# Unbound Configuration
num-threads: 4, msg-cache-size: 50m, rrset-cache-size: 100m
EOF

# Test configuration
sudo unbound -t || sudo unbound configtest

# Reload service
sudo systemctl reload unbound

bash

# Set appropriate permissions
sudo chown -R unbound:unbound /etc/unbound
sudo chmod 750 /etc/unbound

# Enable security features
# See security section for detailed hardening steps

bash

# Enable service
sudo systemctl enable unbound

# Start service
sudo systemctl start unbound

# Stop service
sudo systemctl stop unbound

# Restart service
sudo systemctl restart unbound

# Reload configuration
sudo systemctl reload unbound

# Check status
sudo systemctl status unbound

# View logs
sudo journalctl -u unbound -f

bash

# Enable service
rc-update add unbound default

# Start service
rc-service unbound start

# Stop service
rc-service unbound stop

# Restart service
rc-service unbound restart

# Check status
rc-service unbound status

bash

# Enable in /etc/rc.conf
echo 'unbound_enable="YES"' >> /etc/rc.conf

# Start service
service unbound start

# Stop service
service unbound stop

# Restart service
service unbound restart

# Check status
service unbound status

bash

# Using Homebrew services
brew services start unbound
brew services stop unbound
brew services restart unbound

# Check status
brew services list | grep unbound

powershell

# Start service
net start unbound

# Stop service
net stop unbound

# Using PowerShell
Start-Service unbound
Stop-Service unbound
Restart-Service unbound

# Check status
Get-Service unbound

bash

# Configure performance settings
cat >> /etc/unbound/unbound.conf << 'EOF'
num-threads: 4, msg-cache-size: 50m, rrset-cache-size: 100m
EOF

# Apply system tuning
sudo sysctl -w net.core.somaxconn=65535
sudo sysctl -w net.ipv4.tcp_max_syn_backlog=65535

# Restart service
sudo systemctl restart unbound

bash

# Configure clustering (if supported)
# See official documentation for cluster setup

# Basic load balancing setup example
# Configure multiple instances on different ports

nginx

upstream unbound_backend {
    server 127.0.0.1:53;
    server 127.0.0.1:{default_port}1 backup;
}

server {
    listen 80;
    server_name unbound.example.com;
    return 301 https://$server_name$request_uri;
}

server {
    listen 443 ssl http2;
    server_name unbound.example.com;

    ssl_certificate /etc/ssl/certs/unbound.example.com.crt;
    ssl_certificate_key /etc/ssl/private/unbound.example.com.key;

    location / {
        proxy_pass http://unbound_backend;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        
        # WebSocket support (if needed)
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
    }
}

apache

<VirtualHost *:80>
    ServerName unbound.example.com
    Redirect permanent / https://unbound.example.com/
</VirtualHost>

<VirtualHost *:443>
    ServerName unbound.example.com
    
    SSLEngine on
    SSLCertificateFile /etc/ssl/certs/unbound.example.com.crt
    SSLCertificateKeyFile /etc/ssl/private/unbound.example.com.key
    
    ProxyRequests Off
    ProxyPreserveHost On
    
    ProxyPass / http://127.0.0.1:53/
    ProxyPassReverse / http://127.0.0.1:53/
    
    # WebSocket support (if needed)
    RewriteEngine on
    RewriteCond %{HTTP:Upgrade} websocket [NC]
    RewriteCond %{HTTP:Connection} upgrade [NC]
    RewriteRule ^/?(.*) "ws://127.0.0.1:53/$1" [P,L]
</VirtualHost>

haproxy

frontend unbound_frontend
    bind *:80
    bind *:443 ssl crt /etc/ssl/certs/unbound.pem
    redirect scheme https if !{ ssl_fc }
    default_backend unbound_backend

backend unbound_backend
    balance roundrobin
    option httpchk GET /health
    server unbound1 127.0.0.1:53 check
    server unbound2 127.0.0.1:{default_port}1 check backup

bash

# Set appropriate permissions
sudo chown -R unbound:unbound /etc/unbound
sudo chmod 750 /etc/unbound

# Configure firewall
sudo firewall-cmd --permanent --add-service=unbound
sudo firewall-cmd --reload

# Enable SELinux policies (if applicable)
sudo setsebool -P httpd_can_network_connect on

# Configure fail2ban
sudo tee /etc/fail2ban/jail.d/unbound.conf << 'EOF'
[unbound]
enabled = true
port = 53
filter = unbound
logpath = /var/log/unbound/*.log
maxretry = 5
bantime = 3600
EOF

bash

# Generate SSL certificates
sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 \
    -keyout /etc/ssl/private/unbound.key \
    -out /etc/ssl/certs/unbound.crt

# Configure SSL in unbound
# See official documentation for SSL configuration

PostgreSQL Backend (if applicable)

bash

# Create database and user
sudo -u postgres psql << EOF
CREATE DATABASE unbound_db;
CREATE USER unbound_user WITH ENCRYPTED PASSWORD 'secure_password';
GRANT ALL PRIVILEGES ON DATABASE unbound_db TO unbound_user;
EOF

# Configure unbound to use PostgreSQL
# See official documentation for database configuration

bash

# Create database and user
sudo mysql << EOF
CREATE DATABASE unbound_db;
CREATE USER 'unbound_user'@'localhost' IDENTIFIED BY 'secure_password';
GRANT ALL PRIVILEGES ON unbound_db.* TO 'unbound_user'@'localhost';
FLUSH PRIVILEGES;
EOF

bash

# Kernel parameters
sudo tee -a /etc/sysctl.conf << EOF
net.core.somaxconn = 65535
net.ipv4.tcp_max_syn_backlog = 65535
net.ipv4.ip_local_port_range = 1024 65535
net.core.netdev_max_backlog = 5000
vm.swappiness = 10
EOF

sudo sysctl -p

# Unbound specific tuning
num-threads: 4, msg-cache-size: 50m, rrset-cache-size: 100m

bash

# Configure system limits
sudo tee -a /etc/security/limits.conf << EOF
unbound soft nofile 65535
unbound hard nofile 65535
unbound soft nproc 32768
unbound hard nproc 32768
EOF

yaml

# prometheus.yml configuration
scrape_configs:
  - job_name: 'unbound'
    static_configs:
      - targets: ['localhost:53']
    metrics_path: '/metrics'

bash

# Basic health check script
#!/bin/bash
if systemctl is-active --quiet unbound; then
    echo "Unbound is running"
    exit 0
else
    echo "Unbound is not running"
    exit 1
fi

bash

# Configure log rotation
sudo tee /etc/logrotate.d/unbound << 'EOF'
/var/log/unbound/*.log {
    daily
    rotate 14
    compress
    delaycompress
    missingok
    notifempty
    create 0640 unbound unbound
    postrotate
        systemctl reload unbound > /dev/null 2>&1 || true
    endscript
}
EOF

bash

#!/bin/bash
# Unbound backup script
BACKUP_DIR="/backup/unbound"
DATE=$(date +%Y%m%d_%H%M%S)

mkdir -p "$BACKUP_DIR"

# Stop service (if required)
systemctl stop unbound

# Backup configuration
tar -czf "$BACKUP_DIR/unbound-config-$DATE.tar.gz" /etc/unbound

# Backup data (adjust paths as needed)
tar -czf "$BACKUP_DIR/unbound-data-$DATE.tar.gz" /var/lib/unbound

# Start service
systemctl start unbound

# Clean old backups (keep 30 days)
find "$BACKUP_DIR" -name "*.tar.gz" -mtime +30 -delete

echo "Backup completed: $BACKUP_DIR"

bash

# Stop service
sudo systemctl stop unbound

# Restore configuration
sudo tar -xzf /backup/unbound/unbound-config-*.tar.gz -C /

# Restore data
sudo tar -xzf /backup/unbound/unbound-data-*.tar.gz -C /

# Set permissions
sudo chown -R unbound:unbound /etc/unbound
sudo chown -R unbound:unbound /var/lib/unbound

# Start service
sudo systemctl start unbound

1. Service won't start:

bash

# Check logs
sudo journalctl -u unbound -n 100
sudo tail -f /var/log/unbound/*.log

# Check configuration
sudo unbound -t || sudo unbound configtest

# Check permissions
ls -la /etc/unbound
ls -la /var/lib/unbound

2. Connection refused:

bash

# Check if service is listening
sudo ss -tlnp | grep 53
sudo netstat -tlnp | grep 53

# Check firewall
sudo firewall-cmd --list-all
sudo iptables -L -n

# Test connection
telnet localhost 53
nc -zv localhost 53

3. Performance issues:

bash

# Check resource usage
top -p $(pgrep unbound)
htop -p $(pgrep unbound)

# Check connections
ss -ant | grep :53 | wc -l

# Monitor I/O
iotop -p $(pgrep unbound)

bash

# Run in debug mode
sudo unbound -d
# or
sudo unbound debug

# Increase log verbosity
# Edit configuration to enable debug logging

yaml

version: '3.8'
services:
  unbound:
    image: unbound:latest
    container_name: unbound
    ports:
      - "53:53"
    volumes:
      - ./config:/etc/unbound
      - ./data:/var/lib/unbound
    environment:
      - unbound_CONFIG=/etc/unbound/unbound.conf
    restart: unless-stopped
    networks:
      - unbound_net

networks:
  unbound_net:
    driver: bridge

yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: unbound
spec:
  replicas: 3
  selector:
    matchLabels:
      app: unbound
  template:
    metadata:
      labels:
        app: unbound
    spec:
      containers:
      - name: unbound
        image: unbound:latest
        ports:
        - containerPort: 53
        volumeMounts:
        - name: config
          mountPath: /etc/unbound
      volumes:
      - name: config
        configMap:
          name: unbound-config
---
apiVersion: v1
kind: Service
metadata:
  name: unbound
spec:
  selector:
    app: unbound
  ports:
  - port: 53
    targetPort: 53
  type: LoadBalancer

yaml

---
- name: Install and configure Unbound
  hosts: all
  become: yes
  tasks:
    - name: Install unbound
      package:
        name: unbound
        state: present
    
    - name: Configure unbound
      template:
        src: unbound.conf.j2
        dest: /etc/unbound/unbound.conf
        owner: unbound
        group: unbound
        mode: '0640'
      notify: restart unbound
    
    - name: Start and enable unbound
      systemd:
        name: unbound
        state: started
        enabled: yes
  
  handlers:
    - name: restart unbound
      systemd:
        name: unbound
        state: restarted

Maintenance

bash

# RHEL/CentOS/Rocky/AlmaLinux
sudo dnf update unbound

# Debian/Ubuntu
sudo apt update && sudo apt upgrade unbound

# Arch Linux
sudo pacman -Syu unbound

# Alpine Linux
apk update && apk upgrade unbound

# openSUSE
sudo zypper update unbound

# FreeBSD
pkg update && pkg upgrade unbound

# Always backup before updates
tar -czf /backup/unbound-pre-update-$(date +%Y%m%d).tar.gz /etc/unbound

# Restart after updates
sudo systemctl restart unbound

Regular Maintenance Tasks

bash

# Clean logs
find /var/log/unbound -name "*.log" -mtime +30 -delete

# Verify integrity
sudo unbound --verify || sudo unbound check

# Update databases (if applicable)
sudo unbound-update-db

# Optimize performance
sudo unbound-optimize

# Check for security updates
sudo unbound --security-check

Official Documentation: https://docs.unbound.org/

GitHub Repository: https://github.com/unbound/unbound

Community Forum: https://forum.unbound.org/

Wiki: https://wiki.unbound.org/

Comparison vs BIND, PowerDNS Recursor, Knot Resolver: https://docs.unbound.org/comparison

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Note: This guide is part of the HowToMgr collection. Always refer to official documentation for the most up-to-date information.

1. Prerequisites

2. Supported Operating Systems

3. Installation

RHEL/CentOS/Rocky Linux/AlmaLinux

Debian/Ubuntu

Arch Linux

Alpine Linux

openSUSE/SLES

macOS

FreeBSD

Windows

Initial Configuration

Basic Configuration

Security Hardening

5. Service Management

systemd (RHEL, Debian, Ubuntu, Arch, openSUSE)

OpenRC (Alpine Linux)

rc.d (FreeBSD)

launchd (macOS)

Windows Service Manager

Advanced Configuration

Performance Optimization

Clustering and High Availability

Reverse Proxy Setup

nginx Configuration

Apache Configuration

HAProxy Configuration

Security Configuration

Basic Security Setup

SSL/TLS Configuration

Database Setup

PostgreSQL Backend (if applicable)

MySQL/MariaDB Backend (if applicable)

Performance Optimization

System Tuning

Resource Limits

Monitoring

Prometheus Integration

Health Checks

Log Monitoring

9. Backup and Restore

Backup Script

Restore Procedure

6. Troubleshooting

Common Issues

Debug Mode

Integration Examples

Docker Compose

Kubernetes Deployment

Ansible Playbook

Maintenance

Update Procedures

Regular Maintenance Tasks

Additional Resources