Meet the features: Avast One Firewall

Avast 11 Nov 2021

The Avast One Firewall allows for effective use of firewall capabilities without getting lost in the technical details

You can think of your computer like a house. You don’t want strangers being able to come and go into your house as they please. The same goes with your computer and network traffic. In the early days of computers, they were wide open any system or device could send network traffic to any other system or device. This is one of the ways that large-scale malware attacks of the past, like Blaster in 2002, were able to spread themselves quickly and widely across networks.

Attackers still try to send malicious network traffic to computers. They also use tools to scan for computers to locate them, see how they might be vulnerable to attacks and carry out said attacks.

The solution is to protect your computer with a firewall

Having a firewall on your computer can help protect against scans and attacks. A firewall works to build doors and windows on your system to keep unknown and unwanted network traffic from reaching it.

Firewalls help to better protect your system by working to ensure that only the right, trusted network traffic gets to your system while shielding your system from unknown, unexpected or malicious network traffic.

How the Avast One Firewall works

Firewall is a feature in Avast One free and premium, available for Microsoft Windows.


The free version contains all the same capabilities as the premium version except the premium version also includes:

  • Leak Protection: Leak protection increases your security on public networks by preventing your computer from leaking potentially sensitive info like usernames, computer names, email  etc. This can provide additional protection to travelers and remote workers in particular.  

  • Address Resolution Protocol (ARP) Spoofing Detection: This detects devices on the network that are collecting all the network traffic from your computer. This protects against attacks attempting to collect your network traffic and poses a risk to banking,email, social media and other attacks if the network traffic isn’t encrypted.

  • Port Scan Detection/Alerts: This can detect and alert you  when devices or malicious machines scan your computer for open ports. This can be a sign of a potential attack.

Most networks by default will be treated as Untrusted networks.

To change the firewall’s configuration or disable it, open Avast One. On the left navigation bar, select Explore. Then select Firewall.

Next, click the Firewall button to bring up the configuration page as shown below:

Disabling the firewall

You can disable the firewall entirely by clicking on the green slider next to “Firewall”. When you do this, you will be asked how long you want the firewall to be turned off.

After you select how long you want it to be turned off, you’ll be asked to confirm that you want to turn it off. This is a security feature meant to ensure that the firewall is not being turned off by mistake or by malware.

Once the firewall is turned off, you’ll see it disabled in the configuration panel.

You’ll also see it disabled in the main screen. 

You can easily re-enable the firewall by clicking the red slider.

Configuring the firewall

The firewall differentiates between Trusted and Untrusted networks. It has greater security on Untrusted Networks, but that can make it more difficult to connect to other devices on the network. The firewall has less security on Trusted Networks but can more easily connect to other devices. As noted before, you should only mark a network as a Trusted Network if this is your own network or the network of someone you trust like a family member or friend.

To change a network from Trusted to Untrusted or vice-versa click the down arrow to the right of the network.

On this panel, you can also block specific applications. Doing this will protect your computer from network traffic from these applications. However, this does mean that you will lose any ability to use those applications on the network it effectively cuts them off from the network entirely.

To block an application, click the Apps tab.

You will see Active Apps, Inactive Apps, and All Apps tabs. Select any of these to locate the app you want to block.

Once you locate it in the list, click Block. Once it is blocked, you’ll see it at the bottom of the list as shown above.

You can also click the arrow to the right for more information.

To block the application here, click the Internet access slider so that it shows Blocked.

The History tab enables you to see what traffic the firewall has blocked. You can display what it’s blocked in the Last Hour, Last Day, or Last Month.

Clicking the arrow to the right of each entry will expand it to show you the application, time and firewall activity as shown above.

If you have the Premium version of Avast One, you can enable or disable the Advanced Network Security options as well. These options provide greater protection and should only be disabled for specific reasons.

The Avast One Firewall is built to give your system the best protection for the kind of network your computer is on at the time. It differentiates between Trusted and Untrusted networks, giving the best balance of security and capability appropriate for each kind of network. It provides ways for you to tailor your settings by giving you the ability to change the profile for the network that you’re on, the ability to block specific applications, and to see what the firewall has blocked. By keeping the configuration options simple, it makes it possible to use the firewall effectively without being a networking expert and getting lost in deep technical details.


“Meet the Features” is an ongoing series to help introduce you to specific features in Avast products. It’s meant to help you understand and use a specific feature by explaining the security/privacy problem the feature is meant to solve and how it works so that you can quickly understand and use the feature to better protect yourself.

Have a feature you want to meet? Let us know.

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