Comcast Internet Service Now Fully DNSSEC-Based

Comcast today became one of the first major ISPs in North America to fully run the Domain Name System Security Extensions (DNSSEC) protocol as part of its services.

Jason Livingood, vice president of Internet systems in Comcast's network and operations, today blogged that DNSSEC is now part of its Comcast Constant Guard from Xfinity service. That means that nearly 18 million residential customers of the Xfinity Internet service are using DNS servers that use DNSSEC validation. Comcast's more than 5,000 domain names are also now digitally signed by DNSSEC.

DNSSEC has been gradually rolling out across the Internet over the past year or so. Several major top-level domains, including .com, .org, .net, and .gov, are now DNSSEC-enabled. DNSSEC is a protocol for preventing attackers from redirecting users to malicious websites by redirecting them -- it basically ensures DNS entries remain unchanged in transit and are digitally signed to ensure their authenticity.

[After a sluggish start, DNSSEC is finally catching on after more than a decade in the making. See DNSSEC Finally Comes To .com, But Secure DNS Still Has A Long Way To Go .].

"Now that nearly 20 million households in the U.S. are able to use DNSSEC, we feel it is an important time to urge major domain owners, especially commerce and banking-related sites, to begin signing their domain names. While in the past those domains may have wanted to do so but felt it would have limited effect, they now can work on signing their domains knowing that the largest ISP in the U.S. can validate those signatures on behalf of our customers," Livingood said in his post.

Security expert Dan Kaminsky, who discovered a major DNS caching vulnerability in 2008 that helped expedite DNSSEC's adoption, says he's thrilled that Comcast has stepped up and implemented the protocol. "DNSSEC is the proper fix to my 2008 attack, and I am extremely proud of Comcast for taking this step to protect their users," Kaminsky says. "I am particularly happy that they correctly judged the importance of genuine responses higher than their minor income stream from injecting advertisements.

"The integrity of the DNS is of critical importance to present and future security technologies, and Comcast has done their users a service by investing in DNSSEC," he says.

Now when a Comcast subscriber visits a website, Comcast's DNS servers confirm the domain name and check that its signature is valid and legitimate. Comcast also cryptographically signs its own domain names, like xfinity.com.

Comcast traditionally has been ahead of the curve in security for ISPs. More than two years ago, it was one of the first to employ a bot-notification service that notifies customers whose machines it spots as bot-infected. It then directs the infected user to the antivirus center, where he follows directions to remove the bot malware.

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