Best Free Firewall

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Firewalls help monitor your system's communication between your network and the Internet to help stop intrusions and attacks. They are particularly useful for controlling the activities of Internet facing applications.

No other freeware product has more of a reputation for causing user angst than a firewall. To find a suitable product may involve a process of trial and error. A firewall should protect while not being too intrusive or too complicated to handle. This article gives you a selection of the best free firewalls available.

Firewalls come in two flavours; software based and hardware based. To avoid potential conflicts only install one (third-party) software firewall. You can improve protection, however, by using a hardware "firewall" (such as a router) and a software firewall in conjunction. Modern routers usually have a built-in firewall; consult your router documentation for more details.

Basic firewall protection is critical for securing your PC. Simple firewalls (like the default Windows firewall) limit access to your system and personal information, and silently protect you from inbound threats. We review basic third-party firewalls that have marginally better security than the Windows firewall, such as simpler features for monitoring programs that request outgoing Internet connections (we call this "outbound protection"). The default Windows firewall has only limited outbound protection.

Proactive firewalls have the most extended protection, including HIPS or program monitoring (HIPS Explained), and watch for malicious behavior before malware gets a chance to take control of your PC or turn it into a botnet drone. They seek to achieve stronger "2-way" protection, preventing programs from broadcasting your personal information to the Internet.

Some kinds of malware are best detected by their behavior, so a proactive firewall (or firewall/HIPS combo) is a solid second layer of protection next to your antivirus program. It's an excellent option for high risk users (check out our Security Wizard to see if this includes you). However, it's plausible to argue that a good resident antivirus will stop some malicious threats before they get a chance to make it to the Internet anyway. Many of the top antivirus programs are starting to provide behavioral blocking and extended scanning of network activity.

It's important to use basic or proactive firewall protection, antivirus software for active protection, and safe practices from our "most important advice of all" (Security Wizard).

You can "upgrade" your security by reading the documentation and learning about proactive firewalls or HIPS programs, or using other protection like least-privileged user accounts or Sandboxie or GeSWall.
 

Review Index

• Basic Firewalls
• Firewalls with Strong HIPS
• Related Links
• Quick Selection Guide
   

Additional Tips

• Before installing new resident security products, including antivirus and firewall programs, you may want to make a full drive image. Windows Vista (Ultimate) and Windows 7 have a built in "Complete PC Backup and Restore" feature, or you can use a free drive imaging program. Everyone's system is unique and may have old, latent drivers that are incompatible with whatever you are installing. Not only does drive imaging allow you to recover from unintentional conflicts but also from severe malware infections.
• To cleanly uninstall your (third-party) firewall before installing a new one, you can use ZSoft Uninstaller to analyze before and after the installation. If you haven't used it on your current firewall, try Revo Uninstaller (or other vendor or Windows uninstaller), check for leftover services and drivers with Autoruns, and restart your computer.

Discussion

The built-in Windows firewall is a common choice since it passes all inbound tests (both stealth and open port) and doesn't have many popup alerts. It doesn't require installation, so it's not likely to conflict with your other programs. And many average users may not reliably handle the popup alerts of the best firewalls on the market (especially at their max settings).

If you scan clean for malware and you don't want/need the additional features of a third-party firewall, then the Windows firewall is a practical and useful solution.

You can replace the Windows firewall with a basic third-party firewall for easier control of outbound protection and additional features. Most simple two-way firewalls ask you to allow or deny Internet access for unknown programs. Many automatically allow trustworthy apps and remember your decisions to become silent over time.

First, you can convert a proactive firewall into a basic two-way firewall, making some of the best free firewalls behave with similar silence and protection as ZoneAlarm. Select the following one-click configurations to set them (see the proactive section for more on them):

• Online Armor Free: Right-click its tray icon > uncheck the "Program Guard". It's a user friendly option for this configuration if it doesn't conflict with your other software.
• Comodo Internet Security: Right-click its tray icon > set "Defense+" to "disabled". Or select the "Firewall only" configuration during installation. Make sure to enable rule creation in 'firewall behavior settings' (so you can modify program rules later).

Second, additional third-party firewalls behave similar to the basic configurations of proactive firewalls above. ZoneAlarm, for example, has made a comeback with fewer popups and lighter resource use.

Basic Firewall Reviews

ZoneAlarm Free Firewall 2010 is an excellent inbound/outbound OS firewall solution suited for users of every level of experience. ZoneAlarm protects systems from intrusions as well as program access to the web. ZoneAlarm features an easy-to-understand user interface. Users can adjust security settings for their needs to allow for file/printer sharing, public networks, and even turn off the firewall if ever needed. Simple controls in the form of visual slide bars make setting up this firewall a snap. ZoneAlarm offers to help users setup initial program access with a first-run scan of installed software and allows/denies accordingly. This first scan does not always offer accurate access to programs.

Users will have to interact with this firewall for a time after installation to make sure programs needing LAN or internet access are granted proper permissions. Popups are very simple in format offering Deny, Accept, and a checkbox a user can check to make ZoneAlarm remember the decision. Novice users should be able to easily identify the name of the program asking for web access so they can make the appropriate decision.

The Program Control will allow users to set ZoneAlarm for Low, which is a learning mode and no OS firewall protection and limited popups. Or users can choose Medium, which will make programs ask for permission to access the trusted and internet zones. The high setting is not offered in the Free version of ZoneAlarm. The Smart Defense Advisor will help reduce popups by offering settings for programs asking for access, based on the decisions made by other users worldwide. Users can choose whether or not to participate in ZoneAlarm's community defense program. Users can set programs access manually at anytime by going to ZoneAlarm's Program Control and selecting Programs.

Internet Zone controls are divided into the Trusted Zone, used for the local network to share files, printers, etc., and the Internet Zone for communication to/from the web. A simple 3-position format allows users to choose from "No protection" (firewall is off), Medium (Allows file/printer sharing), and High (will allow users to connect to a network but will not allow anyone else to connect to your system). The medium setting is recommended for home networks with more than one system, and for users whose modem requires this setting. The high setting is most recommended for single-system web access (only one computer at home and modem does not require a home network setting), and for public areas such as cafes, restaurants, and hotels (etc.) with wifi.

ZoneAlarm Free offers basic two-way defense, stealth mode, and anti-phishing protection. However, it lacks HIPS or program-to-program protection.

 Windows 7 Firewall Control is a good choice for those intending on using the Windows built-in Firewall. Despite its name, the program is compatible with Windows XP and higher. In a nutshell, Windows7FirewallControl allows the user to configure the Windows firewall to block or allow applications from connecting to the internet; it adds better outbound protection configuration to the built-in Firewall. It is based on the Windows Filtering Platform (which is what the built-in firewall is also based on), so unlike most other firewalls it does not install any third party drivers. The user interface is clean and simple, reflecting what this program does (ie. block or allow application access - nothing more).

There are three modes a user can choose from; Normal, DisableAll, or EnableAll. DisableAll disables all applications regardless of program settings, while EnableAll allows all application access (essentially equivalent to switching off the firewall completely). Unless needing to test something specifically, the Normal Mode is the recommended one - applications/programs are allowed or denied access depending on the rules set.

Under the Normal Mode, when a program tries to access the internet for the first time (upon installation of W7 Firewall Control) a window pop-ups with information on what the application is, the publisher, etc (assuming default program settings). You can then allow or disallow access, either permanently or as a one-time basis. Selecting the former option will add the settings permanently to the Programs list, while with the latter option you will have to deal with the pop-up window again on the next launch.

In addition to the window pop-up for new programs, activities that take place (ie. blocked/allowed traffic, etc) are logged and shows up in the bottom right corner of your screen. Both the pop-up window and log activity notification dialogue can be turned on or off at the user's discretion.

That's basically all there is to it. It may get a bit annoying when you first starting using it, since you will have to define the initial rules for all your applications (ie. allow or disallow them); this includes everything from Internet Explorer to your antivirus program. Nevertheless, Windows7FirewallControl allows much greater and easier control over the built-in firewall than what the operating system offers.

Discussion

The following personal firewalls provide excellent network and HIPS protection. Each firewall comes with default settings and shouldn't require much adjustment except for the needs of advanced users.

Firewall products in this section require more time to learn than basic firewalls (to get the most out of them). Since firewalls are often praised for their security effectiveness at their max settings, users will likely have lower protection than mentioned by independent testing sources like Matousec. All of the product vendors seek to provide user friendly features, sometimes incorporating reduced levels of protection in their default settings (by decreasing some HIPS monitoring).

Proactive Firewall Reviews

Comodo Firewall is the best choice for users seeking a full featured security suite. This latest release is suitable for both lightly-skilled users (still must have knowledge of installed programs) and technically advanced users. Its robust and active HIPS (or application monitoring feature), called "Defense+", matches or exceeds the security performance of pay products. Comodo allows for much control and customization for the curious or the paranoid.

Comodo includes a "memory firewall" (against buffer overflow attacks) and a light sandbox component to limit the way unknown applications and new software installations affect your computer. The use of sandbox protection limits the negative effects of malware. It maintains a lengthy list of known safe applications, but if an unknown application attempts entry through the firewall, Comodo will deny the application and ask the user what to do. The new release contains user friendly features by default while allowing experienced users to maintain control over ports, protocols, and configurations.

During installation the user has three firewall installation options to choose from:  Firewall Only, and Firewall with Optimum or Maximum Proactive Defense (ie. the Defense+ feature as mentioned earlier). After installation Comodo automatically selects "Safe Mode", which generates numerous popup alerts for applications not in its trusted vendors list (you can browse this list to see if you trust the vendors: go to the Defense+ tab > "Common Tasks" > "View My Trusted Software Vendors"). When you answer "allow" and "remember your answer" to popup alerts for an application, Comodo creates a custom policy for it. Some of its policies are fairly liberal.

In the more liberal "Clean PC Mode", Defense+ automatically treats all applications on your drive as safe (but if any malware is currently hidden on your drive, it too would be considered safe). Applications still receive some minimal monitoring for Comodo's two protected lists ("my protected registry keys" and "my protected COM interfaces") and for running as an executable, or more/less monitoring depending on their custom policy. And new files get sent to a list of files "waiting for your review" in the "Summary" page. Files listed for review will be considered possibly unsafe and will provoke popup messages, as if in Safe Mode, until their custom policies are made.

Comodo limits the frequency of alerts by automatically treating some programs as safe and allowing some applications to access the Internet. You can additionally automate the behavior of Defense+ by one or more of these methods for treating applications as safe:

• Have it "remember your answer" to all popup alerts when an application first runs, which works for some applications (because some custom policies set this way are close to "trusted" status). But if an application still nags you, click "More Options" in the alert and use the drop down box to select "trusted" or "blocked" (etc.), if available, or set an application to trusted manually ("Defense+" > "Advanced" > "Computer Security Policy" > "Edit..." > "Use a Predefined Policy"), which finally ceases popup alerts and most intrusion prevention for that application.
• Add files to the lists of "My Own Safe Files" or "My Trusted Software Vendors" in the interface (see the "Defense+" tab), which is most helpful for "Safe Mode" or "Paranoid Mode".
• Use the "Clean PC Mode" (right-click the tray icon and select it under the "Defense+ Security Level"). But make sure to scan and remove any malware first.

The following guides may also contain useful information about Comodo's settings: How to Install Comodo, How to Tame Comodo Defense+ Without Disabling It, and MC's Mini Tutorial.

A solid contender is the free version of Online Armor Free. It has outstanding leak-test and HIPS performance (the HIPS feature is mostly in its "Program Guard"). It has a unique feature called "run safer" that allows you to selectively set risky applications (web browsers, office software, readers/viewers, instant messengers, email or news programs, multimedia software, download managers, etc.) to run as if under a limited user account (go to "Programs" tab > uncheck "Hide Trusted" > highlight a program and click "Run Safer"). It minimizes popup alerts over time with its automatic list of safe programs, your on-demand scans with its safety check wizard, and your responses to popup alerts -- especially in cases where you tell it to remember your decisions and have it treat programs as trustworthy.

Run the wizard and have it search your PC for known programs to allow/block/ask. In this case, Online Armor relies on you to respond to alerts for unknown programs. For the curious or paranoid user, it uses excellent popup messages when it automatically allows a program to connect online and, optionally, when it automatically trusts a program/process to run (these alerts don't require user action and they can be enabled/disabled in the interface with "Options" > "Firewall", and "Programs" > "Options"). For example, I noticed a message when it auto trusted a key logger test, but after I set the tester to untrusted, it gave very informative and detailed security alerts (and then it passed the test and logged the tester in the interface under the "Key Logger" tab, but it only logged the key logger after the test was untrusted). You can even close both its tray tools from its right-click context menu. They are not needed for the firewall and HIPS components to continue running and protecting.

Outpost Firewall Free is a good choice for users who want highly flexible protection without sacrificing usability. It was obviously made with average users in mind, judging by the care taken to simplify alert messages and make it easy to adjust intrusion prevention (or HIPS) monitoring. For example, it remembers your responses to popup alerts without the need to set "trusted" rules (like in Comodo/Online Armor), and like Online Armor it notifies you when it automatically allows an application to access the Internet (especially helpful during the learning phase).

The free version lacks many extras of the pay version, however, such as automatic updates and the ability to break active connections. The HIPS component is called "Host Protection" in the interface. It provides four default levels of protection, which can be easily set with a slider and additionally customized item by item by advanced users. The default "optimal" setting only monitors the "most dangerous activities" (such as memory injections, driver loads, and a healthy list of system critical features -- auto starts, shell extensions, and internet settings) instead of all program activities. But these "optimal" settings lack protection from keyloggers, direct disk accessing, DNS API request monitoring, etc. You can check the types of reduced monitoring in "Settings..." > "Host Protection" > "Customize...".

The installation asks whether you want to train the firewall for a week (using its Auto-Learn mode and Rules Wizard). In this mode, it sets rules automatically for known safe applications.

A former commercial product, Private Firewall is now unrestricted freeware. It is a proactive multi-layer security solution, offering behaviour blocking technology alongside standard firewall protection. Using Behavioral-based Monitoring, it features zero-hour virus, spyware, and malware protection, process and application security, and registry protection, just to name a few. It is definitely a feature-packed firewall/HIPS solution.

 While there is a decent help file available, the user interface can be a bit confusing and overwhelming. There are many configurable settings, and sorting through them may require some time. To help out with that there is a information menu on the right of each screen which explains what each section is for. Training mode allows all actions within a 180-second interval, which is ideal for installing or running programs for the first time. On the first run after installing however, Private Firewall still managed to disable Panda Cloud Antivirus, the antivirus software on my test system, even with Training mode activated. Adding Panda Cloud Antivirus to the allow list seemed to solve this minor issue.

It is also possible to set different security levels for the Internet and the Network. Various levels of protection (High, Low, and Custom) can be separately specified for Internet Access and Network Security (ie. file and printer sharing). This is useful for, say, when one needs to access the internet via a network they don't quite trust. In addition, there are three profiles you can choose: Home, Office, and Remote. You can set appropriate settings for each one and easily switch between them as needed; this is particulary useful for portable computers which connect to many different networks. Another useful feature is that it is possible to block all outbound email; simply click the 'Block Outbound Email' icon in the main user screen and all outbound email should be blocked.

Overall, Private Firewall is a very effective firewall; it ranks among the top products on Matousec. A number of members at our forum speak highly of the developers of Private Firewall, and the software itself is quite trusted. However, it is slightly tailored for the more advanced users. Beginner computer users may want to consider another firewall instead, but if you are comfortable with the basics of Windows, you should definitely consider Private Firewall.

AVS Firewall differs from other regular ones in that it comes with additional protection modules; namely a registry defender, a banner blocker, and parental control options – it is something like a suite. The firewall itself does not have as many configurable options as some of the firewalls listed on this page, but the standard selections are still there – off, which turns off the firewall; custom, which allows you to set your own connection rules; and high, which blocks all connections.

Each section of the program is displayed clearly; navigation is through the menu on the left. Alerts are generally clear and straightforward, as is configuration.

The registry defender protects the registry from being modified, with the option of only protecting select categories. The parental control limits the list of websites that can be accessed, but you must manually add each website to be trusted, ie. You cannot block specific websites; you can only allow certain websites. The anti-banner component blocks undesirable web page content including ads, flash banners, pop-ups and the like. All three of these additional modules can be disabled independently as desired. AVS Firewall also comes with a monitoring utility so you can check the size of network traffic which is sent and received by each application.

During installation of this firewall, the installer automatically installs the AVS Software Browser; there is no option to opt-out of installing this, but the program can be removed separately after installation with no affect on the actual firewall program. The installer also has a pre-checked option to install AVS Registry Cleaner, and it is recommended that it is unchecked so the installer does not install it.

Despite trying to bundle in a few additional programs by the vendor, AVS Firewall is a decent firewall program.  It has some additional features not found in your everyday firewall program, though most of those features can be found in other third party programs.

• Sygate Personal Firewall (Windows 2000/XP/2003) [No Longer Supported]
• NetVeda Safety.Net (Windows 95/98/Me/NT/2000/XP, requires registration) [No longer supported]
• Ashampoo FireWall Free (Windows 2000 SP4, XP SP2) [No longer supported]
• Filseclab Personal Firewall (Windows 95/98/Me/NT/2000/2003/XP, 32-bit) [No longer supported]

Related to Firewalls

• Comprehensive List of Firewalls (PBSLW)
• Best Free Intrusion Prevention and Detection Utility (HIPS)
• HIPS Explained
• Matousec Proactive Security Tests Analyzed

Security Guides

• Security Advice Wizard
• Probably the Best Security List in the World
• Gizmo's Guide to Securing Your PC
• Safe Computing in Under an Hour
• Best Free Security Diet Plan
• How to Stay Safe While Online
• How to Improve Security When Using a Public Terminal

Security Products

• Best Free Antivirus Software
• Best Free Browser Protection Utility
• Best Free Adware/Spyware/Scumware Remover
• Best Internet Safety Check Freeware
• Best Free Software Update Monitor
• Best Free Encryption Utility
• Best Free Anonymous Surfing Service
• Best Free Drive Imaging Program
• Best Free Password Manager

Inbound Vulnerability Tests

• Nessus (open ports test, vulnerability scan)
• GRC ShieldsUp! (stealth test)
• Audit My PC (open ports test)
• Nmap Online (open, closed, filtered, unfiltered ports test)
• Security Space (open ports test)
• Symantec Security Scan (open ports test)
• SecurityMetrics (stealth test)

Outbound Vulnerability Tests

• Matousec Proactive Security Challenge (testing suite results)
• Matousec SSTS/BSODhook (a suite of tests for experts). It may receive antivirus warnings, but they are false positives.

Learn More

• How Firewalls Work
• Wilders Security: Firewall Questions for Beginners
• Microsoft: Firewall FAQ
• US-CERT: Understanding Firewalls
• OnGuard Online (threat information)

Your opinion matters! If you've used one of these firewalls before, or know of another outstanding freeware firewall, let us know in the comments section below. For a more comprehensive discussion, please visit our forum.

This software category is maintained by volunteer editor Tim; registered site visitors can contact Tim by clicking here