When you install Comodo Firewall, you're given a choice of whether to install only the basic firewall, the "Firewall with Optimum Proactive Defense" (which also protects against malware which can bypass firewalls), or the Firewall with Maximum Proactive Defense+, which does what "Firewall with Optimum Proactive Defense" does, plus protecting against "leaks", information about things such as open ports on your PC being sent out over the Internet. The higher the level of protection, the greater the intrusiveness of the firewall, so you'll have to balance protection against annoyance when making your choice. You can always change the level of protection later, when you're running the program.
Installing the program is a complicated affair that requires close attention. At defaults, you could end up with bundled products and a new home page (more on that later). Once you're in the program, things get more straightforward. After you install Comodo Firewall , when an application needs to make an Internet connection, the firewall will ask whether you want to allow that connection. If you know the application, allow it to make the connection; if you don't, tell the firewall to block it. These popups are annoying, but Comodo cuts down on their number, because it knows about a number of applications that it knows are safe, such as browsers and email clients, and lets those through without any questions.
For basic operation, that's all that you need to know, although if you want to customise Comodo's functioning, you can do that as well. There's also a wealth of techie information available, but most people won't need it, and will be satisfied to let the firewall work on its own.
If you use Maximum Proactive Defense+, you'll also be asked when programs try to make certain system changes, such as altering portions of the Registry. Again, you'll have to balance safety with being annoyed. You can also turn that part of the program on and off.
More important than interface for a firewall is effectiveness, and here Comodo Firewall Pro shines, according to the Matousec.com set of firewall tests. It rates Comodo Firewall Pro well ahead of other firewalls, over the last year, the firewall rated 95% every time it was tested. By way of contrast, Norton Internet Security's firewall ratings range between 66% and 71%, McAfee's were at 12%, Panda Internet Security between 4% and 12%, ZoneAlarm Free at 11%, and ZoneAlarm Pro at 72%.
Keep in mind that installing Comodo Firewall is a chore and an annoyance unto itself. After downloading the entire Comodo Internet Security package, you can choose to install an antivirus application, the firewall, a 30-day trial of Comodo's LivePCSupport, or any combination of the three. For this review, we installed only the firewall, the "Firewall with Optimum Proactive Defense."
Also, during installation the Comodo Firewall will change your default search engine to Ask.com, make Hopsurf.com your home page, and will install the Hopsurf.com toolbar, unless you uncheck those options during installation. And you can also choose to use Comodo's DNS servers instead of your default DNS servers, although the default is to use your own servers.
Should you use this firewall? If you're willing to put up with a very annoying installation procedure, and don't mind occasional interruptions, Comodo Firewall's a keeper. It's a strong firewall, and you certainly can't beat the price. If the installation issues turn you off, you might want to try a less intrusive firewall such as ZoneAlarm, or merely use the ones built into Windows.