6 DNS services protect against malware and other unwanted content

While many (but not all) users are familiar with the concept of security software, there are more basic ways to protect unwary surfers from phishing sites, botnets, intrusive advertising and other unwanted visitors: DNS services.

First, a quick primer for those who are unfamiliar with DNS: You utilize the Domain Name System (DNS) every time you surf the Web. Each time you type a site name into the browser, DNS is queried for the IP address corresponding to that particular domain, so the browser can contact the Web server to get the content. (The process of converting the domain name to its IP address is called domain-name resolution.)

There are actually two main types of DNS servers: recursive and authoritative. The ones that are used by most individuals and small companies (and that are covered here) are called recursive DNS and are the default services provided by most Internet Service Providers (ISPs). All the companies listed here offer recursive DNS services. Some of them, however, also sell authoritative DNS services, which allow website owners or hosts to define the Web server IP addresses that their domain names point to and to manage other DNS settings.

Since DNS servers are the middlemen between your browser and website content, there are many third-party DNS services that offer additional functionality for both users and network administrators. These tools can include:

• Content filtering. This can be conveniently implemented to block adult sites and other unwanted content, while requiring no software on the computers and devices.
• Malware and phishing blocking. This can be performed by the content filtering tool also, to block sites containing viruses, scams and other dangerous content.
• Protection against botnets. This blocks communication with known botnet servers so your computer isn't taken over.
• Advertisement blocking. This is another type of content filtering, which some DNS services specifically concentrate on.
• URL typo correction. For instance, if you typed gogle.com it would correct to google.com .

In this article, I identify and describe several of these services. Many -- in fact, most -- are either completely free of charge or offer a number of free features that might make it worth your while to take a look.

Because there are so many DNS services available, for this list I chose those that provide some type of automatic or preconfigured content filtering (and I describe where you are sent when the filter kicks in, which can range from a straight "nothing to be found here" page to an ad-filled cacophony).

It's easy to switch to a different recursive DNS service. Simply change the IP addresses for DNS in the Internet settings of your router to apply it to the entire network, or change the DNS settings on select computers or devices. Without further intervention, you'll receive the DNS service's preconfigured security or filtering protection. Some services also allow you to create an account to customize the level of protection and messages that appear when a site is blocked.

Remember, the speed, reliability and performance of DNS servers can vary. Slow or poor domain resolution can translate into slower and less reliable web browsing. You can run speed tests on DNS servers (I recommend namebench ) so that you can compare their performance at your particular location.

Comodo Secure DNS

Free for: Personal use only

DNS Addresses: 8.26.56.26 and 8.20.247.20

Comodo Secure DNS offers a simple free service for personal use. It is preconfigured to block harmful websites, such as those containing malware, spyware and phishing attempts. Additionally, it claims to offer a more reliable, faster and smarter DNS service than those provided by most ISPs.

Like Dyn, Comodo also sells services that include authoritative DNS services for websites and many other security solutions, such as SSL certificates, secure email services, antivirus and even PCI compliance services.

When a site is blocked by Comodo Secure DNS, a warning page is displayed. It shows the reason why the page is blocked and allows the user to disregard and continue to the blocked site anyway. When a user continues to a blocked site, he or she can choose how long to allow access to the site.

In the case of nonexistent or unresponsive domains, users see a page called Comodo Secure DNS Search. Suggested search terms or phrases are displayed based upon the domain they're trying to visit, in addition to a search field. One big downside of the search: Although the site says the results are powered by Yahoo, only sponsored links are given and are not true search results.

Keep an eye out for future updates from Comodo. Currently in beta, Comodo SecureDNS 2.0 offers customizable content filtering and is also being marketing towards businesses.

Dyn Internet Guide

Free for: Personal or business use

DNS Addresses: 216.146.35.35 and 216.146.36.36

Dyn Internet Guide is a free service offered to the general public for personal or commercial use. Its basic preconfigured service automatically blocks malware and phishing sites, and offers typo correction.

Dyn also offers authoritative DNS services: hostnames for remote access and full DNS solutions for websites.

In addition, Dyn offers customizable content filtering if you create an account. You can block up to 30 pre-defined content categories and create custom white- and blacklists. Although it offers an Internet Guide subscription the company says is free, to use it you must sign up for Dyn's separate, fee-based Remote Access (DynDNS) service. Pricing for Remote Access starts at $25/year (there is a 14-day free trial). Additionally, you must log in every 30 days to keep your free Internet Guide account active.

Dyn offers two other Internet Guide subscriptions: Pro at $10/year and Premium at $20/year; neither requires the Remote Access service if your Internet connection uses a static IP address. Both provide the same functionality -- additional static or dynamic addresses, defense plans, whitelists and blacklists -- with the more expensive option offering more of each. The Pro and Premium plans also provide access to phone and email support.

When a user tries to visit a site that's been blocked by the content filtering settings of Internet Guide, an alert page is shown citing the reason why the page is blocked. When a site is detected as malware or phishing via the Internet Guide's automatic protection, the user is allowed to bypass and continue to the site -- unless that particular site or content category has been explicitly blocked via Internet Guide's settings.

For nonexistent or unresponsive domains, users by default see the Internet Guide showing search results related to the non-working domain with a Google-like look and feel. If you create a free or premium account, you can optionally disable this Internet Guide feature.

FoolDNS

Free for: Personal or business use

DNS Addresses: 87.118.111.215 and 213.187.11.62

FoolDNS provides both free and commercial services, targeted towards home and small business use. It's primarily designed to block online tracking, profiling and advertisements, but also blocks malware and phishing sites.

The premium services include additional functionality and are offered in two different versions. The Audit version adds reporting, logging and the ability to create white- and blacklists. The Business version adds filtering of 2 million unsafe domains, more reporting capabilities and the ability to customize filtering via 20 predefined categories.

When a page is blocked -- for example, if there is malware detected -- a very simple page is shown saying the domain is filtered. No landing page is displayed for nonexistent or unresponsive domains, allowing the Web browser to display its own default error page.