# Firewalls and Firewalld in Ubuntu

In today's interconnected world, protecting your systems from unauthorized access is non-negotiable. This is where **firewalls** come in, serving as your first line of defense against potential cyber threats. If you're using Ubuntu and want to efficiently manage your firewall, **Firewalld** is a tool you should know about. In this post, we'll explore what firewalls are, why they matter, and how to use Firewalld to secure your Ubuntu system.

### **What is a Firewall?**

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1734221864441/e2496a07-02d8-41b4-9830-47bea4f02d6d.png align="center")

A **firewall** is like a security guard for your network. It monitors traffic entering and leaving your system and decides whether to allow or block it based on predefined rules. Firewalls are crucial for:

* **Blocking Unwanted Traffic:** Preventing hackers and malicious programs from gaining access.
    
* **Allowing Trusted Services:** Ensuring that essential services like SSH or web servers are accessible.
    
* **Monitoring and Controlling Traffic:** Keeping tabs on what’s happening in your network.
    

Think of it as a filter that only lets the right people in while keeping the wrong ones out.

Now, let’s use **Firewalld** - a powerful and flexible firewall management tool for Linux to experiment with firewalls.

Firewalld is a dynamic firewall. It allows you to make real-time changes without restarting the entire service. Here are a few reasons to use Firewalld:

* **Zone-based Configuration:** You can define trust levels for network connections using zones.
    
* **Real-time Changes:** Add or remove rules without interrupting active connections.
    
* **Integration with iptables:** It simplifies the complexity of managing iptables directly.
    

### **Install Firewalld**

Firewalld isn’t installed by default on Ubuntu, but you can get it up and running in just a few steps:

```plaintext
sudo apt update  
sudo apt install firewalld  
sudo systemctl start firewalld  
sudo systemctl enable firewalld  
```

These commands update your package lists, install Firewalld, and ensure it starts automatically whenever your system boots.

### **Checking Firewalld Status**

Once installed, verify that Firewalld is active:

```plaintext
sudo systemctl status firewalld  
```

If it’s running, you’ll see “active (running).”

### **Firewalld Basics**

Now that you have Firewalld installed, we will quickly run through some basics about configuring it.

**Zones in Firewalld**

Zones are the core of Firewalld’s functionality. They define trust levels for your network connections. Common zones include:

* **Public:** For untrusted networks, like public Wi-Fi.
    
* **Home:** For trusted networks, like your private Wi-Fi.
    
* **Work:** For office networks with medium trust levels.
    

You can view active zones with:

```plaintext
firewall-cmd --get-active-zones  
```

**Allowing a Service**

Let’s say you’re hosting a website and must allow HTTP traffic. Run:

```plaintext
firewall-cmd --add-service=http --permanent  
firewall-cmd --reload  
```

**Blocking a Service**

To block a service like SSH, use:

```plaintext
firewall-cmd --remove-service=ssh --permanent  
firewall-cmd --reload  
```

### **Practical Example: Securing a Web Server**

Imagine you’re hosting a web application on an Ubuntu server.

*PS: Instead of imagining, you can run a simple site inan Apache server and try securing it*

Here’s how you can secure it with Firewalld:

1. **Allow HTTP Traffic:**
    

```plaintext
firewall-cmd --add-service=http --permanent  
firewall-cmd --reload  
```

2. **Block Other Traffic:**
    

Remove unnecessary services (e.g., SSH):

```plaintext
firewall-cmd --remove-service=ssh --permanent  
firewall-cmd --reload  
```

3. **Verify Rules:**
    

Check active rules to ensure only HTTP is allowed:

```plaintext
firewall-cmd --list-all  
```

This will display the active zone and its rules.

Firewalls are essential for securing your systems. Take a moment today to try and practically implement and play around with this.