Basic UFW setup guide for Debian/Ubuntu

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Introduction to UFW

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Installation

sudo apt update
sudo apt install ufw

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Basic UFW commands

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Check UFW status

sudo ufw status

sudo ufw status verbose

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Enable and disable UFW

sudo ufw allow 22/tcp
sudo ufw enable

sudo ufw disable

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Managing basic rules

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Allow incoming connections

sudo ufw allow 22    # Allow SSH
sudo ufw allow 80    # Allow HTTP
sudo ufw allow 443   # Allow HTTPS

sudo ufw allow ssh
sudo ufw allow http
sudo ufw allow https

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Deny incoming connections

sudo ufw deny 23     # Deny Telnet

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Delete rules

1. List rules with numbers:

sudo ufw status numbered

2. Delete a specific rule:

sudo ufw delete [number]

sudo ufw delete allow 80

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Advanced configuration

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Allow specific IP addresses

sudo ufw allow from 203.0.113.4

sudo ufw allow from 203.0.113.4 to any port 22

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Configure default policies

sudo ufw default deny incoming
sudo ufw default allow outgoing

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Best practices

1. Always allow SSH first Before enabling UFW, ensure SSH access is allowed:
   sudo ufw allow ssh
   
2. Use specific rules Instead of allowing all traffic to a port, specify the service and protocol:
   sudo ufw allow 80/tcp
   
3. Regular audits Regularly review your firewall rules:
   sudo ufw status verbose
   
4. Back up rules Back up your UFW rules periodically:
   sudo cp -a /etc/ufw /root/ufw-backup
   

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Common configuration examples

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Basic web server setup

# Allow SSH, HTTP, and HTTPS
sudo ufw allow ssh
sudo ufw allow http
sudo ufw allow https

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Database server setup

# Allow MySQL/MariaDB from specific IP
sudo ufw allow from 203.0.113.4 to any port 3306

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Rate limiting

sudo ufw limit ssh

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Troubleshooting

1. Check UFW status
   sudo ufw status verbose
   
2. View UFW logs
   sudo tail -f /var/log/ufw.log
   
3. Reset UFW Resetting UFW deletes configured rules and disables it. Use this only when deliberately rebuilding the firewall with console access available:
   sudo ufw reset
   

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Conclusion