UFW

Enable UFW

Before enabling UFW, ensure that OpenSSH is allowed to prevent being locked out of your server:

sudo ufw allow OpenSSH

Now you can safely enable UFW:

sudo ufw enable

Check UFW Status

sudo ufw status

Set Default Policies

Set the default policies to deny incoming and allow outgoing traffic:

sudo ufw default deny incoming
sudo ufw default allow outgoing

Allow Specific Services or Ports

Allow HTTP and HTTPS:

sudo ufw allow 'Nginx HTTP'
sudo ufw allow 'Nginx HTTPS'

Allow a specific port, such as SSH:

sudo ufw allow 22

Allow a specific IP to connect to a certain port:

sudo ufw allow from 192.168.1.0/24 to any port 3306

Deny Specific Ports

Directly deny a specific port:

sudo ufw deny 23

Delete Rules

Remove a rule that allows a particular service, such as 'Nginx HTTP':

sudo ufw delete allow 'Nginx HTTP'

Reset UFW

Reset UFW to the default state; all rules will be deleted:

sudo ufw reset

Disable UFW

Disable UFW to allow all traffic:

sudo ufw disable

Additional Commands for Specific Scenarios

1. Set Named Services: Some services register with UFW, such as 'Nginx Full', which can be used to allow both HTTP and HTTPS.

   sudo ufw allow 'Nginx Full'
   

2. Check Status with Details: Verify the final status to ensure the settings are correct.

   sudo ufw status verbose
   

3. Logging: Enable logging to monitor security issues.

   sudo ufw logging on
   

These commands will help effectively manage your server's UFW firewall rules, ensuring security and proper service operation.