By default, the firewall performs a series of checks to determine if a network is public or private

How the Avast Firewall works

Firewall is a feature in Avast Free Antivirus and Avast Premium Security, available for Microsoft Windows.

The free version contains all the same capabilities as the premium version, while 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. These attacks pose  a risk to banking, email, social media and other attacks if the network traffic isn’t encrypted.
• Port Scan Detection/Alerts: The feature 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.

By default, the firewall performs a series of checks to try and determine if a network is Public or Private. A home network is an example of a Private network, while a coffee shop's Wi-Fi network is an example of a Public network.

To change the firewall’s configuration or disable it, open Avast Free Antivirus or Premium Security.

On the left navigation bar, select Protection. 

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

Disabling the Firewall

Here, 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 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 such as printers, speakers, and smart home devices among others.. 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 Show Settings to the right of the network.

You can configure the firewall to block on a per-application basis. To do this, click on Apps. This will bring up the Application panel and you can click Block to the right of the application you want to block.

To see the firewall logs, click on Logs which will bring up the firewall log listing.

“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.