Best Free Firewall

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A firewall protects your system from unwanted intruders. It also protects your system from programs that will send out or broadcast your personal information. You could think of a firewall as being a security system like the entry door on your residence. If you have no door, intruders could freely enter or leave your residence and have full access to everything in it. When you have a firewall on your system, it's like installing and then locking the door to your residence. No one can get in except you and those who are allowed access by you, whether you give them a key, "buzz them in," or you open the door for them when asked.

Firewalls that are doing their job will often tell you there's someone at the door (trying to communicate with or gain access to your system) and ask if you want to let them in. A popup appears telling you someone/something is trying to connect to you, or that a program wants access to the internet. The alert may show a name of a network, a program, a website, or even an ip address. The firewall will ask you what you want to do and it's up to you if you want to open the door (to your system) or not.

Many people misunderstand alerts (often popup alerts) from their firewalls. It is very important to be able to have control over your system and to be aware of who or what is trying to gain access to it, and to know what communication is originating from your system. Firewall alert messages should never be seen as a nuisance.

There are some malicious programs that get into your system and "prop the back door open" or they "make a key to your door" for themselves. This is done by masquerading as a harmless program and at a predetermined time or action, this program you thought was harmless will unleash its destructive power as the virus it truly is. A virus in your system may modify your hosts file and even turn your system into a cyber-soldier in a huge botnet army. Your personal information can be broadcast across the web to criminals who will destroy your good name. These are a type of trojan which is a very dangerous type of malware. A common symptom of a compromised hosts file is whenever you turn on your computer or open your browser, you are automatically directed to one or multiple nasty websites. You will feel as though you've lost all control of your system.

It is extremely important to have a good firewall installed to control access to your system and protect your personal information. It is also equally important to install antivirus software and maybe additional security protection for your system. An effective firewall monitors your system's communication with your local network (if any) and the internet to help stop intrusions and attacks. Some firewalls offer additional protective features such as host file lock, internet lock, custom IP address filtering, and more.

If you want to learn more about firewalls, visit these excellent sites: How Firewalls Work, How Firewalls Protect Your PC and Microsoft Security Firewalls FAQ. If you decide not to use one of the firewall products in the article, please be sure your Windows Firewall is active. NEVER use more than one software firewall on one system at the same time. You may, however, use a hardware and a software firewall in conjunction to improve protection.

Before installing your new firewall:

First and foremost, you should back up your system and partitions. While installing new security software, you may encounter unforeseen difficulties which may result in system instability or system failure. Everyone's system is different and very unique. You may have an old, latent driver in your system that is incompatible with whatever you are installing. To avoid frustration, loss of data, and possibly therapy, you should always back up your data to a separate partition on your hard drive (the same size or larger than the partition you are backing up), or you should back up your information to an external hard drive. It is far easier to restore a system from a backup archive or image than it is to resurrect a damaged operating system that no longer boots. Now that I have made my point perfectly clear to readers, the backup software I recommend is Paragon Backup & Recovery free edition. Install, backup your system and move on to the next step.

Before installing a new firewall (or other security/suite), you must completely uninstall any previous firewall (or security suite). [This only applies to third party firewall products. If you are using the Windows firewall included with your operating system, you can simply install the new firewall according to the product instructions.]

After uninstalling, the system must be rebooted as most uninstallers have a built-in cleaner to finish removing remaining components of the software. At this time it's a good idea to run a drive cleaner to remove all remaining temporary files. I recommend CCleaner.

Experienced users may even want to run a registry cleaner included in this software. I recommend using caution when cleaning your registry. This is only an optional step. If you are in doubt, and you really don't know what you are doing, then perhaps you should leave your registry alone. If you are going to clean your registry, I ONLY recommend CCleaner to novices and those with moderate experience. I have used CCleaner's registry cleaner thousands of times on numerous systems and have never had a problem with it, unlike other registry tools. If you do decide to clean your registry with CCleaner, make sure you backup your registry entries when prompted to do so with CCleaner.

Once you have uninstalled the old firewall, cleaned the file system and the registry (if you chose to do so), reboot the computer and you are ready for a fresh installation on your new firewall (or other security/suite). I hope users will choose one of the great free firewalls we tested and reviewed in this article!

Today the use of reliable firewalls is IMPERATIVE as we face a new age of cybercrimes like identity and data theft! A good firewall will not only thwart attacks by hackers but is your first line of defense in keeping your personal information in your hands alone. No firewall or any security software can certainly guarantee 100% protection certainty. As technology changes, criminals change and attacks on systems, and even malware becomes more sophisticated everyday. I want to be clear that though I have information posted in this article for very old, unsupported firewalls, I will only recommend current, actively supported firewalls and security solutions.

- Cyberlightning
 

The following Free Firewall article is presently undergoing a major revision. I thank you for your patience.

I. Best Software Firewalls for Maximum Protection and Greater User Involvement

The following personal firewalls provide excellent network protection. Each firewall comes with default settings and shouldn't require much adjustment except for the needs of advanced users. Some information for configuration is provided whenever possible to help you learn about your firewall and to better suit it to your needs.

Firewall products in this section may require a fair amount of time to learn their features. Some products rely of lists of known safe applications, safe vendors, or valid digital signatures. Some products can optionally give safe or trusted status to all your current files, some have training or installation modes, and some have lesser configurations to reduce monitoring.

Since firewalls are often praised for their level of protection at their maximum security settings, users may not have the degree of protection mentioned in the reviews below if they reduce security levels using the firewall interface, or if users employ methods to increase automation in order to reduce alerts.

Comodo Firewall is the best choice for users seeking a full featured security suite. It has a robust and a very active HIPS or application monitoring feature called "Defense+", which matches or exceeds the security performance of pay products. Comodo also provides a "memory firewall" which in their words, “Cutting-edge protection against sophisticated buffer overflow attacks.” Comodo allows for much control and customization, with a plethora of additional settings to adjust for the curious or for the paranoid. This latest release of Comodo is suitable for both lightly-skilled users (still must have knowledge of installed programs) and technically advanced users.

Comodo includes a very effective Sandbox component to limit how many applications and new software installations affect your computer. The use of sandbox protection helps to limit the negative effects of malware if some terrible infection manages to enter your system. Comodo Firewall boasts a “Default Deny Protection” for applications. Though they maintain a lengthy list of known safe applications in their database, 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 many new features while allowing experienced users to maintain absolute control over their system by controlling ports, protocols, and complete configuration command.

During installation, it gives you a choice between two levels of security. The "Firewall Only" mode (discussed in the next section) and the Comodo Internet Security (includes antivirus, antimalware, and additional features). After installation Comodo automatically selects "Safe Mode" which maximizes proactive protection to a high level, and is the best mode for most users. It will generate 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.

 Take a look at this guide on How to Install Comodo (version 4.1)

The following guides are far outdated and being reviewed for update so they are relevant to the current release of Comodo, but you are welcome to look at them anyway for any useful information that might help you: How to Tame Comodo Defense+ Without Disabling It and Comodo Forum Help.

Alternatively, see this mini guide (currently reviewing for update relevant to current version of Comodo) for an example of how to maximize some of its basic settings. Comodo nicely allows you to quickly increase or decrease protection with its different modes, configurations, and settings.

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 (Zemana, which it failed initially), 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.

Zone Alarm Free Firewall 2010 is an excellent inbound/outbound OS firewall solution suited for users of every level of experience. Zone Alarm protects systems from intrusions as well as program access to the web. Zone Alarm 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. Zone Alarm 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. 

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.

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. The popups are very easily understood most of the time, listing the program name or the name of the executable file asking for access. Most often programs executable files contain the name of the program followed by ".exe" so even novice users should be able to easily identify the name of the program asking for web access so they can make the appropriate decision. Popups are very simple in format offering Deny, Accept, and a checkbox a user can check to make Zone Alarm remember the decision.

The Program Control will allow users to set Zone Alarm 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 Zone Alarm. 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 Zone Alarm's community defense program. Users can set programs access manually at anytime by going to Zone Alarm's Program Control and selecting Programs.

Zone Alarm Free offers very good HIPS protection, Inbound/Outbound defense, Stealth mode, Anti-phishing protection, identity theft protection, and now even offers 2 GB free online backup. Zone Alarm Free 2010 passed all leak and hack testing with flying colors. The only negatives I can name is lack of program-to-program protection offered by the free version, which includes programs reaching out to the web through a web browser.

Note to those using or planning to install Immunet Protect: Zone Alarm products are not compatible with Immunet Protect and at this time there is no work-around for this incompatibility. Immunet Protect and Zone Alarm products (any Zone Alarm product - free or commercial) will cancel each other out and neither one will function in your system. Development is continuing and Immunet hopes to release a version someday that will be compatible with Zone Alarm.

 This review is currently undergoing revision.

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.
 

II. Best Software Firewalls for Basic Protection and Less User Involvement

(This section is currently undergoing revision) 

Some users (of many degrees of experience) prefer to avoid advanced firewalls that employ a constant "security guard" that question them daily. The following alternatives accommodate the use of your favorite active security programs, such as other HIPS software, active anti-malware, or browser protection (virtualization, isolation, rights reduction).
 

Firewall Only ("Set it and Forget it Options")

The built-in Windows firewall is a common choice since it passes all inbound tests and it doesn't have popup alerts. It lacks proactive security against outbound malware intrusions, but some users are simply unprepared to reliably handle the numerous popup alerts of the best firewalls on the market. And users who click "allow" to each and every popup alert will not have the level of protection they think they have. If you're fairly sure malware isn't on your computer and you don't want the other features of a third party firewall, then the Windows firewall is actually a practical and useful solution.

You could marginally increase security with the alternate configurations below or with the default "no popup" settings of Sunbelt-Kerio. But Windows firewall doesn't require installation, so it's the least likely to crash your PC or conflict with your other programs.
 

Nearly "Silent" Firewall Configurations

If you disable or reduce program monitoring in the following firewalls, they still provide limited inbound/outbound protection/filtering, but still offer more features than the built-in Windows firewall.

Select the appropriate installation options or settings to reduce the proactive monitoring components in these firewalls:

• Outpost Firewall Free: Comes with reduced monitoring in its default settings, the top choice for this section if you can put up with the ads. And you can further reduce or disable intrusion protection if it becomes too much of a nag -- right click the tray tool > "Settings..." > "Host Protection" > and select "Low" on the slider (to disable anti-leak protection). Also in "Host Protection", you could select "Customize..." to manually configure proactive monitoring.
• Comodo Internet Security: Right-click its tray icon > set "Defense+" to "disabled", or select the "Firewall only" configuration during installation. Or you could manually reduce its Defense+ monitoring in the interface Defense+ tab: "Advanced" > "Defense+ Settings".
• Online Armor Free: Right-click its tray icon > uncheck the "Program Guard". It's a very lightweight and attractive option for this configuration if it doesn't conflict with your other software.
  
• Privatefirewall: In the interface > "Process Monitor" tab > move the slider to "Off". It will still alert you to some programs starting for the first time since that doesn't count as a process (of a running program).
   

Cautions

Though these less proactive choices will greatly reduce important protection from malware running on your PC, such as root-kits, keyloggers, Trojans, viruses, adware, or spyware. As editor I warn you that I DO NOT recommend reducing security settings just to reduce popup alerts. The alerts are serious and are designed to protect you and your personal information. Most firewalls will remember decisions you make regarding program access if you instruct the firewall to do so.

I highly recommend using secure DNS providers (OpenDNS or Comodo SecureDNS), site safety advisers (WOT), software update monitors (Secunia PSI), and, especially, browser protection (Sandboxie, GeSWall) to avoid malware problems in the first place. And our site has related articles that cover other security essentials: anti-virus software, anti-spyware software, HIPS software, etc.

Several other free firewalls were brought up in comments here or noted from other sources. As they are not rated in this review, they are listed here with brief descriptions and links to their sites for ease of reference.

Additional Options for Simplicity and Basic Protection: I recommend the firewalls in section II, but if they don't work for you one of these might. No complete test results exist for the proactive components of these firewalls, but in general they aren't as good as the max security modes of the firewalls in section I. Loosely ordered from best to worst all around:

• Sunbelt-Kerio Personal Firewall. Pros: Simple setup, silent "no popup" mode, lightweight on memory, automatic updates, built-in help, optional behavior blocker, and more features than windows firewall. Cons: Loses its HIPS, some logging, and password protection after 30 days. It has many advertisements for its full commercial version. Some users experienced system crashes in the comments recently and in the past, but I had no problems with it in my testing. Details: XP, Vista, 32-bit only, 5.71 MB. Download here.

• Windows 7 Firewall Control. Pros: Simple setup, safe to install (uses Windows filtering platform and doesn't install third-party kernel drivers), very light and works without the tray icon, built-in help, more features than Windows firewall. Cons: Fails GRC stealth test (it set many ports to closed on my system, so it passed other inbound testing sites), popup alerts/settings may not be for average users, doesn't auto allow known safe applications, doesn't display network activity, and bans editing system application rules in the free version. Details: Vista, Windows 7, 32/64 bit versions, portable version (32-bit only), 1.11 MB.

This section is for firewalls whose support is considered to be "end-of-life." These firewalls are no longer being developed and therefore may pose a risk to your system's security and possibly stability.

PC Tools Firewall Plus

Support Ended September, 2010. Because support for this product ended so recently, it will remain a viable firewall solution for a period of time. However, users should beware that support has ended for this product so it will eventually become more and more vulnerable to breech, attack, and stability.

This firewall provides a HIPS-like component through its "enhanced security verification," which alerts the user about possibly malicious behavior. It relies on a list of known programs and a check for digital signatures to significantly reduce the frequency of popup alert messages, so it will mainly ask you about unknown programs, programs connecting online, and programs requiring more access. It seems more liberal and user friendly in its default settings than previous versions, giving fewer popup alerts for common tasks. Easy installation. fails the Zemana key logger test when it's set to automatically allow programs with valid digital signatures.

Users can still download this firewall by clicking here.

Firewalls Compatible with Older Versions of Windows:

• Sygate Personal Firewall [No Longer Supported]
• NetVeda Safety.Net (Windows 98-XP, requires registration) [No longer supported]
• Ashampoo FireWall Free (Windows 2K/XP) [No longer supported]
• Filseclab Personal Firewall Professional Edition (Windows 95-2003, 32-bit only)
• Ghostwall (Windows 2K-XP, 64-bit compatible)
• Windows 2000: see Outpost Firewall Free, Privatefirewall

General Firewall Sources and Information:

• TSA Articles: Matousec Personal Firewall Tests Analyzed, HIPS Explained
• Test results: Matousec Proactive Security Challenge.
• Inbound testing: GRC ShieldsUp!, SecurityMetrics, Audit My PC, Security Space, Symantec Security Scan, Hacker Watch.
• Other tests: PC Flank Tests, Zemana Key logger Test, Matousec SSTS/BSODhook (a suite of tests for experts, free for personal use). Some receive antivirus warnings, but they are non-malicious.

TSA Security Advice and Guides:

• Security Advice Wizard: Get personalized results and our security team's up-to-date suggestions.
• Probably the Best Security List in the World: Read Ako's excellent suggestions.
• Gizmo's Guide to Securing Your PC: Increase computer security with safe practices.
• How to Surf More Securely: Improve security with Sandboxie or DropMyRights.
• How to Block Bad Websites: Three different ways to prevent your PC from being infected by accidentally visiting a malicious or compromised website.
• Safe Computing in Under an Hour: Read MidnightCowboy's excellent suggestions.
• Spyware Removal Guide: Clean up after using bad practices or verify that you are malware free.
• How to Improve Security When Using a Public Terminal: Learn how to type passwords & more.
• How to Remove Google Text Ads
• How to Reduce Spam

TSA Security Software Articles:

• Best Free Intrusion Prevention and Detection Utility for Home Use (HIPS)
• Best Free Antivirus Software
• Best Free Adware/Spyware/Scumware Remover
• Best Internet Safety Check Freeware
• Best Free Browser Protection Utility
• Best Free Encryption Utility
• Best Free Software Update Monitor
• Best Free Password Manager
• Best Free Trojan Scanner/Trojan Remover
• Best Free Anonymous Surfing Service
• Best Free Secure Erase Utility
• Best Free Spam Filter for the Average User
• Best Free Spam Filter for the Experienced User
   

Find more free software at The Editors' Choice List: Our Selection of the Best PC Freeware!

You are invited to share and discuss your views in our freeware forum. To post in the forum you need to register first but that's quick and immediate. Alternatively, anyone can leave a comment at the bottom of this page. You can also help us by rating this review at the end of the article.

This software category is maintained by volunteer editor Cyberlightning

All free firewalls featured in this article have been tested extensively using a wide range of tools to measure the quality of the product, its effectiveness at every security level, reliability, overall performance, resource consumption, bandwidth usage during operation, real-time protection versus passive protection, leak testing, stealth testing, HIPS (if available), hack defense, user-friendliness, and even installation/uninstallation.

What else would you like to see in this article and/or category? I have received suggestions for a Novice section, a Linux Firewall section, some helpful videos, more screenshots, more links, more voting/contests, and even a request for a sort of "complete idiot's guide" for firewalls. Help me answer more questions and improve this category and article by making suggestions! Make suggestions in the Comments section below or if you are a registered user on this site, feel free to send me a PM. And for those of you finding press releases for products, or offering tips & tricks: Keep them coming. Your knowledge and experience may go a very long way to help another user. For readers who are novices with firewalls or computers in general, please continue to read and learn!

The only dumb question is one that is not asked.