OpenDNS — security and DNS provider of choice for 2% of all Internet users — is blocking the Flashback Trojan, or what’s being described as one of the single biggest Mac security incidents of all time. As OpenDNS does in cases of very large scale attacks like this, the protection is included in Premium DNS and completely free to users. People not yet using OpenDNS need only to set up the service on their wireless router, computer or device to secure their computers and devices from the attack. (OpenDNS also offers Umbrella, a security service for businesses that includes comprehensive malware and botnet protection.)

If you’re already using OpenDNS services, no action is required to get the protection. It was enabled for you automatically. In addition to protection from Flashback, OpenDNS will also protect you from future, widespread attacks and make your Internet both faster and more reliable.

What is Flashback, and how does OpenDNS protect me?

The Internet is abuzz with news about Flashback, because until very recently it was commonly believed that Macs are largely immune to malware and attacks. Some reported numbers about infections are as high as 600,000, with a reported 56% of those infections on U.S. soil. Flashback was first discovered in September of last year, when it was designed to look like a Adobe Flash update (hence its name). But as of this month, it’s now infecting users that visit compromised websites. Once infected, the malware will attempt to connect to a server for command and control. Flashback has a built-in algorithm, which calculates the domain for C&C.

OpenDNS is far and away the most ideal measure Internet users can take to protect their machines from Flashback, as OpenDNS is a proactive, preventative measure. It’s the only solution that doesn’t require software or installing of anything. All Mac users should switch to OpenDNS now to prevent infection, and avoid a scenario where infection occurs and disinfection is necessary. As our friends over at F-Secure note regarding Flashback, “Caution: Manual disinfection is a risky process; it is recommended only for advanced users. Otherwise, please seek professional technical assistance.” Even for those people who find their machine has already been infected by Flashback, enabling OpenDNS will prevent the malware from connecting to its command and control and causing your machine any damage.

Not yet using OpenDNS?

Here’s how to set up the free service: Simply create an account, choose your router or computer and follow the step-by-step instructions. Note that setting up OpenDNS on your router will protect all devices connecting to the Internet through your WiFi network, and that Windows users should use OpenDNS, too.

Already using OpenDNS?

Rest assured you’re protected, but tell everyone you know who isn’t to set up OpenDNS for themselves. Or better yet, do it for them.