What is Netplan?

Netplan is a network configuration tool used in Ubuntu for managing network settings. It utilizes YAML files to define network configurations in a clear and manageable format. Netplan reads these configuration files and applies the settings using various network rendering methods, such as NetworkManager or systemd-networkd. The beauty of Netplan lies in its ability to simplify network configuration and make it more readable and easier to maintain.

In the past, network configuration in Ubuntu required manual edits to multiple files. Netplan brings all of that under one umbrella, making it more structured and user-friendly.

Steps to Assign a Static IP Address with Netplan

To assign a static IP address using Netplan, you need to edit the appropriate configuration file. These files are typically found in the /etc/netplan/ directory and have a .yaml extension. The default filename is usually something like 00-installer-config.yaml, but it may vary depending on the system.

Follow these steps to configure a static IP address:

1. Open the Terminal and Get Root Access:
   First, open your terminal and gain root privileges to make changes to the configuration files.

   sudo -i

2. Edit the Netplan Configuration File:
   Now, you need to edit the Netplan configuration file. You can use any text editor, but we will use nano for this example. If the default configuration file exists, open it as follows:

   sudo nano /etc/netplan/00-installer-config.yaml

If the file doesn’t exist, you may need to create it or check for files in the directory.

3. Edit the Configuration File to Assign the Static IP Address:
   Once the file is open, you need to specify your network interface and static IP settings. Below is an example configuration:

   network:
     version: 2
     renderer: NetworkManager
     ethernets:
       enp1s0:
         addresses:
           - 172.16.1.61/24
         nameservers:
           addresses: [8.8.8.8, 8.8.4.4]
         routes:
           - to: default
             via: 172.16.1.1

Explanation:

• version: 2: Specifies the version of Netplan configuration.
• renderer: NetworkManager: Tells Netplan to use NetworkManager for managing the network.
• ethernets: The section where you define the Ethernet interface, in this case, enp1s0.
• addresses: Specifies the static IP address (e.g., 172.16.1.61/24), where /24 denotes the subnet mask.
• nameservers: Specifies the DNS servers to use, in this case, Google’s DNS servers (8.8.8.8 and 8.8.4.4).
• routes: Defines the default gateway, which is the IP address that packets will be routed to if they are not for the local network (in this case, 172.16.1.1).

1. Save and Close the File:
   After making the necessary changes, save and close the file. In nano, you can do this by pressing CTRL + X, then Y to confirm changes, and finally Enter to save the file.
2. Apply the Netplan Configuration:
   To apply the new network configuration, run the following command:

   sudo netplan apply

This command applies the new network settings, including the static IP address you specified.

Testing the Configuration

Once the configuration is applied, you can check if the static IP address has been successfully assigned by using the following command:

ip a

This command will display a list of network interfaces and their assigned IP addresses. You should see the static IP address you assigned (e.g., 172.16.1.61) listed under the appropriate network interface.

Additional Tests

To ensure the network is functioning correctly, you can perform a few additional tests:

• Ping the Gateway:
  To verify that the network gateway is reachable, run:

  ping 172.16.1.1

If you receive responses from the gateway, it means the route is correctly set.

• Check DNS Resolution:
  You can verify that DNS is working properly by running:

  nslookup google.com

This will query the DNS server to ensure that domain names are being resolved correctly.

Conclusion

Netplan is an excellent tool for managing network configurations in Ubuntu. Assigning a static IP address with Netplan is straightforward and involves editing a single YAML file. This process helps maintain clear and easy-to-manage network configurations, especially for systems that require consistent network settings.

By following the steps in this guide, you should be able to configure a static IP address on your Ubuntu system quickly and effectively.

Thanks to its integration with Ubuntu’s system firewall infrastructure, UFW operates reliably while maintaining compatibility with system-level operations.

In this tutorial, we will explore how to list and delete UFW firewall rules effectively. Additionally, we’ll address some frequently asked questions about UFW to provide a comprehensive understanding of its functionality.

Advantages of UFW

1. Simplicity: UFW offers an accessible interface for users of all technical skill levels, making firewall management straightforward.
2. Security: By effectively filtering network traffic, UFW prevents unauthorized access to your computer or network, enhancing overall system security.
3. Integration: Built on top of iptables, UFW seamlessly integrates with Ubuntu’s system firewall, ensuring reliable operation and compatibility.
4. Flexibility: UFW allows users to create inbound and outbound rules, providing detailed control over network traffic and enabling customization for specific requirements.
5. Logging: UFW makes it easy to enable logging, which is useful for troubleshooting or monitoring firewall activities for security purposes.

Prerequisites

• You must have sudo privileges to execute UFW commands.

Step 1: Listing UFW Rules

One of the most common tasks in firewall management is listing rules. To check the status of UFW and view all rules, use the following command:

sudo ufw status

Output:

If UFW is disabled, you’ll see the following:

Status: inactive

If UFW is enabled, the output will display all active firewall rules:

Status: active

To                         Action      From
--                         ------      ----
22/tcp                     ALLOW       Anywhere          
22/tcp (v6)                ALLOW       Anywhere (v6)

For more detailed information, use the status verbose command:

sudo ufw status verbose

Output:

This will provide information about logging, default policies, and new profiles:

Status: active
Logging: on (low)
Default: deny (incoming), allow (outgoing), disabled (routed)
New profiles: skip

To                         Action      From
--                         ------      ----
22/tcp                     ALLOW       Anywhere          
22/tcp (v6)                ALLOW       Anywhere (v6)

To see numbered rules, use the status numbered command. This is particularly useful when adding or deleting specific rules:

sudo ufw status numbered

Example Output:

Status: active

     To                         Action      From
     --                         ------      ----
[ 1] 22/tcp                     ALLOW IN    Anywhere
[ 2] 80/tcp                     ALLOW IN    Anywhere
[ 3] 443/tcp                    ALLOW IN    Anywhere
[ 4] 8069/tcp                   ALLOW IN    Anywhere

Step 2: Deleting UFW Rules

There are two primary methods to delete UFW rules:

1. By rule number
2. By specification

Note: Always ensure you are deleting the correct firewall rule to avoid accidentally blocking essential services like SSH (default port 22).

Step 3: Deleting Rules by Rule Number

Start by listing all rules and identifying the rule number of the rule you want to delete:

sudo ufw status numbered

Use the following command to delete a rule by its number:

sudo ufw delete [rule_number]

Example:

To delete rule number 4:

sudo ufw delete 4

You will be prompted for confirmation:

Deleting:
 allow 22/tcp
Proceed with operation (y|n)? y

Press y and hit Enter. The rule will be deleted:

Rule deleted

Important: The rule numbers will shift after each deletion, so always verify the list before proceeding with further deletions.

Step 4: Deleting Rules by Specification

An alternative method is to delete rules using their specifications. For example, if you previously allowed traffic on port 2222:

sudo ufw allow 2222

You can delete this rule by specifying it directly:

sudo ufw delete allow 2222

Step 5: Resetting UFW

If you need to disable UFW and delete all active rules, use the reset command:

sudo ufw reset

This will deactivate UFW and restore it to its default configuration, removing all rules in the process.

Frequently Asked Questions

1. What is the UFW rate limit?

By default, UFW limits SSH connections from a single IP address to six attempts within 30 seconds to prevent brute-force attacks.

2. Can I delete multiple firewall rules at once?

Unfortunately, UFW doesn’t provide a native option to delete multiple rules simultaneously. Each rule must be deleted individually.

3. How can I delete all UFW firewall rules at once?

You can reset UFW using the sudo ufw reset command to delete all rules and return to the default configuration.

4. How do I view UFW firewall rules without numbering them?

Use the sudo ufw status command to see a list of firewall rules without numbers.

5. How can I check specific details of a firewall rule, such as the associated ports or IP addresses?

You can view the details of a rule using the sudo ufw show [rule_number] command, which displays its configuration.

6. Is it possible to list UFW rules showing resolved IP addresses instead of just port numbers?

Yes, you can use the sudo ufw show resolv command to display rules with resolved IP addresses.

7. How can I delete all inactive UFW rules?

Run the following command to remove all inactive rules, retaining only the active ones:

sudo ufw delete inactive

Conclusion

We hope this detailed guide has helped you understand how to list and delete UFW firewall rules. UFW simplifies firewall management, making it accessible for users of all levels while maintaining robust security features.

If you have any questions or doubts, please feel free to share them in the comments section below. We’ll be happy to assist!