Ten Years of Passive DNS

The report, "A Decade of Passive DNS" provides a longitudinal analysis of the use and popularity of top-level domains over a ten-year period. The findings are based on what Farsight Security has seen in passive DNS from 2010-2019 based on a ten-year data rollup, excluding DNSSEC-related records. This study allows us to report on four measures for that period for each of the 1,576 IANA-recognized TLDs. more

Nation Scale Internet Filtering—Do’s and Don’ts

If a national government wants to prevent certain kinds of Internet communication inside its borders, the costs can be extreme and success will never be more than partial. VPN and tunnel technologies will keep improving as long as there is demand, and filtering or blocking out every such technology will be a never-ending game of one-upmanship. Everyone knows and will always know that determined Internet users will find a way to get to what they want, but sometimes the symbolic message is more important than the operational results. more

The Limits of Notice and Takedown

In The Limits of Filtering, Evan Engstrom and Nick Feamster argue eloquently that the costs of a "takedown-staydown" system to defend against copyright infringement would be prohibitive for online service providers (OSPs) and therefore deprive OSPs of otherwise interested investors. I agree that Engstrom and Feamster raise some valid points, particularly including that content recognition technologies are not perfect... However, we must also remember that the current DMCA regime imposes significant costs... more

Notice, Takedown, Borders, and Scale

I was on the front lines of the SOPA wars, because SOPA touched on two matters of strong personal and professional importance for me: protecting the Internet infrastructure, and protecting the economy from Internet related crime. I've continued to study this field and advise industry participants in the years since then. The 2017-02-20 paper by Annemarie Bridy entitled Notice and Takedown in the Domain Name System: ICANN's Ambivalent Drift into Online Content Regulation deserves an answer, which I shall attempt here. more

Let Me Make Yeti-DNS Perfectly Clear

The following rather alarming text caught my eye today... Had the text appeared under a less august letterhead, or signed by less qualified authors, there would be no cause for alarm. However, the letterhead was World Economic Forum and the authors were William J. Drake, Vinton G. Cerf, and Wolfgang Kleinwächter. As one of three coordinators for the Yeti-DNS project, this feels a bit like I'm in big trouble now. So, let's discuss the matter. more

Internet Security Marketing: Buyer Beware

As security breaches increasingly make headlines, thousands of Internet security companies are chasing tens of billions of dollars in potential revenue. While we, the authors, are employees of Internet security companies and are happy for the opportunity to sell more products and services, we are alarmed at the kind of subversive untruths that vendor "spin doctors" are using to draw well-intentioned customers to their doors. Constructive criticism is sometimes necessarily harsh, and some might find the following just that, harsh. But we think it's important that organizations take a "buyers beware" approach to securing their business. more

Secure Unowned Hierarchical Anycast Root Name Service - And an Apologia

In Internet Draft draft-lee-dnsop-scalingroot-00.txt, I described with my coauthors a method of distributing the task of providing DNS Root Name Service both globally and universally. In this article I will explain the sense of the proposal in a voice meant to be understood by a policy-making audience who may in many cases be less technically adept than the IETF DNSOP Working Group for whom the scalingroot-00 draft was crafted. I will also apologize for a controversial observation concerning the addition of new root name servers... more

Painting Ourselves Into a Corner with Path MTU Discovery

In Tony Li's article on path MTU discovery we see this text: "The next attempt to solve the MTU problem has been Packetization Layer Path MTU Discovery (PLPMTUD). Rather than depending on ICMP messaging, in this approach, the transport layer depends on packet loss to determine that the packet was too big for the network. Heuristics are used to differentiate between MTU problems and congestion. Obviously, this technique is only practical for protocols where the source can determine that there has been packet loss. Unidirectional, unacknowledged transfers, typically using UDP, would not be able to use this mechanism. To date, PLPMTUD hasn't demonstrated a significant improvement in the situation." Tony's article is (as usual) quite readable and useful, but my specific concern here is DNS... more

Wow! BIND9 9.10 Is out, and What a List of Features!

Today the e-mail faerie brought news of the release of BIND9 9.10.0 which can be downloaded from here. BIND9 is the most popular name server on the Internet and has been ever since taking that title away from BIND8 which had a few years earlier taken it from BIND4. I used to work on BIND, and I founded ISC, the home of BIND, and even though I left ISC in July 2013 to launch a commercial security startup company, I remain a fan of both ISC and BIND. more

Extreme Vulnerability at the Edge of the Internet - A Fresh New Universal Human-Rights Problem

By design, the Internet core is stupid, and the edge is smart. This design decision has enabled the Internet's wildcat growth, since without complexity the core can grow at the speed of demand. On the downside, the decision to put all smartness at the edge means we're at the mercy of scale when it comes to the quality of the Internet's aggregate traffic load. Not all device and software builders have the skills - and the quality assurance budgets - that something the size of the Internet deserves. more

On the Time Value of Security Features in DNS

There are some real problems in DNS, related to the general absence of Source Address Validation (SAV) on many networks connected to the Internet. The core of the Internet is aware of destinations but blind to sources. If an attacker on ISP A wants to forge the source IP address of someone at University B when transmitting a packet toward Company C, that packet is likely be delivered complete and intact, including its forged IP source address. Many otherwise sensible people spend a lot of time and airline miles trying to improve this situation... The problems created for the Domain Name System (DNS) by the general lack of SAV are simply hellish. more

DNS Firewalls In Action - RPZ vs. Spam

In general, a network firewall is just a traffic filter... Filtering rules can be anything from "allow my web server to hear and answer web requests but not other kinds of requests" to "let my users Ping the outside world but do not let outsiders Ping anything on my network." The Internet industry has used firewalls since the mid-1980's and there are now many kinds, from packet layer firewalls to web firewalls to e-mail firewalls. Recently the DNS industry has explored the firewall idea and the results have been quite compelling. In this article I'm going to demonstrate a DNS firewall built using RPZ (Response Policy Zones) and show its potential impact on e-mail "spam". more

DNS Changer

One fine night in November 2011 I got an opportunity to get my hands dirty, working on a project for the United States Federal Bureau of Investigation (FBI). They were planning to seize a bunch of computing assets in New York City that were being used as part of a criminal empire that we called "DNS Changer" since that was the name of the software this gang used to infect a half million or so computers. more

Refusing REFUSED

The U.S. Congress' road to Stopping Online Piracy (SOPA) and PROTECT IP (PIPA) has had some twists and turns due to technical constraints imposed by the basic design of the Internet's Domain Name System (DNS). PIPA's (and SOPA's) provisions regarding advertising and payment networks appear to be well grounded in the law enforcement tradition called following the money, but other provisions having to do with regulating American Internet Service Providers (ISPs) so as to block DNS resolution for pirate or infringing web sites have been shown to be ineffectual, impractical, and sometimes unintelligible. more

DNS Policy is Hop by Hop; DNS Security is End to End

The debate continues as to whether ISP's can effectively filter DNS results in order to protect brand and copyright holders from online infringement. It's noteworthy that there is no argument as to whether these rights holders and their properties deserve protection - nobody is saying "content wants to be free" and there is general agreement that it is harder to protect rights in the Internet era where perfect copies of can be made and distributed instantaneously. What we're debating now is just whether controlling DNS at the ISP level would work at all and whether the attempt to insert such controls would damage Secure DNS (sometimes called DNSSEC). more

The Myth of the Unintended Infringer in SOPA and PIPA

In a recent op-ed piece in TheHill.COM, some friends and I described the futility of mandated DNS blocking as contemplated by the SOPA (H.R. 3261) and PIPA (S. 968) bills now working their way through the U.S. Congress: No Internet user is required to use the Domain Name servers provided by their ISP. And if millions of American citizens who for whatever reason want to engage in online piracy can no longer do so because Congress has passed this law and their ISP is now filtering the citizen's DNS lookups... more

Technical Comments on Mandated DNS Filtering Requirements of H. R. 3261 (“SOPA”)

About two months ago, I got together with some fellow DNS engineers and sent a letter to the U. S. Senate explaining once again why the mandated DNS filtering requirements of S. 968 ("PIPA") were technically unworkable. This letter was an updated reminder of the issues we had previously covered... In the time since then, the U. S. House of Representatives has issued their companion bill, H. R. 3261 ("SOPA") and all indications are that they will begin "markup" on this bill some time next week. more

Protecting Intellectual Property is Good; Mandatory DNS Filtering is Bad

It has been about six months since I got together with four of my friends from the DNS world and we co-authored a white paper which explains the technical problems with mandated DNS filtering. The legislation we were responding to was S. 968, also called the PROTECT-IP act, which was introduced this year in the U. S. Senate. By all accounts we can expect a similar U. S. House of Representatives bill soon, so we've written a letter to both the House and Senate, renewing and updating our concerns. more

Defense in Depth for DNSSEC Applications

At the time of this writing DNSSEC mostly does not work. This is not a bad thing - in fact it's expected... There is a significant last-mover advantage DNSSEC deployment (or IPv6 deployment) and that can't be helped. It's all in a good cause though - everybody knows we need this stuff and some farsighted contributors put a lot of money and other resources into DNSSEC years or decades ago to ensure that when the time comes the world will have a migration path. Sadly, this leaves current investors and application designers and developers wondering whether there's a market yet. more

Alignment of Interests in DNS Blocking

I've written recently about a general purpose method called DNS Response Policy Zones (DNS RPZ) for publishing and consuming DNS reputation data to enable a market between security companies who can do the research necessary to find out where the Internet's bad stuff is and network operators who don't want their users to be victims of that bad stuff... During an extensive walking tour of the US Capitol last week to discuss a technical whitepaper with members of both parties and both houses of the legislature, I was asked several times why the DNS RPZ technology would not work for implementing something like PROTECT-IP. more

Domain Names Without Dots

Now that ICANN has approved a potentially vast expansion in the number of generic Top-Level Domains, there's considerable interest in and confusion about how these names can be used. For example if someone registers "dot BRAND", can they advertise http://brand/ and have it work? more

Using Domain Filtering To Effect IP Address Filtering

In Taking Back The DNS I described new technology in ISC BIND as of Version 9.8.0 that allows a recursive server operator to import DNS filtering rules in what ISC hopes will become the standard interchange format for DNS policy information. Later I had to decry the possible use of this technology for mandated content blocking such as might soon be the law of the land in my country. I'm a guest at MAAWG this week in San Francisco and one of the most useful hallway discussions I've been in so far was about the Spamhaus DROP list. more

Two Stage Filtering for IPv6 Electronic Mail

I'm a guest at the MAAWG conference in San Francisco this week and several people have now mentioned to me the problem and the opportunity of anti-spam e-mail filtering for IPv6. Tomorrow is World IPv6 Day but since a bunch of the pieces have clicked together in my head I'll post this a day early. more

Anycast, Unicast, or Both?

A long time ago in an Internet far away, nobody paid for DNS services. Not directly at least. We either ran our own servers, or got DNS service as part of our IP transit contract, or traded services with others. In ~1990 I was the operator of one of the largest name servers in existence (UUCP-GW-1.PA.DEC.COM) and I exchanged free DNS secondary service with UUNET. Two thousand zones seemed like a lot of zones back then -- little did we dream that there would some day be a billion or so DNS zones world wide. more

On Mandated Content Blocking in the Domain Name System

COICA (Combating Online Infringement and Counterfeits Act) is a legislative bill introduced in the United States Senate during 2010 that has been the topic of considerable debate. After my name was mentioned during some testimony before a Senate committee last year I dug into the details and I am alarmed. I wrote recently about interactions between DNS blocking and Secure DNS and in this article I will expand on the reasons why COICA as proposed last year should not be pursued further in any similar form. more

COICA and Secure DNS

As a strong proponent of the private right of action for all Internet endpoints and users, I've long been aware of the costs in complexity and chaos of any kind of "blocking" that deliberately keeps something from working. I saw this as a founder at MAPS back in 1997 or so when we created the first RBL to put some distributed controls in place to prevent the transmission of unwanted e-mail from low reputation Internet addresses. What we saw was that in addition to the expected costs (to spammers) and benefits (to victims) of this new technology there were unintended costs to system and network operators whose diagnostic and repair work for problems related to e-mail delivery was made more complex because of the new consideration for every trouble ticket: "was this e-mail message blocked or on purpose?" more

Whois Scared?

Every time I witness another argument about changing the rules of the Whois system I marvel at how such an important core internet protocol could be so widely misunderstood. I don't mean that the protocol's technical details are not well understood -- it's a very simple device, easy to implement correctly and easy to use even for new users. I mean that the Whois system itself and its purpose in the Internet ecosystem is widely misunderstood. Everybody uses Whois and lots of people argue about Whois but precious few folks know why Whois exists in the first place. more

Taking Back the DNS

Most new domain names are malicious. I am stunned by the simplicity and truth of that observation. Every day lots of new names are added to the global DNS, and most of them belong to scammers, spammers, e-criminals, and speculators. The DNS industry has a lot of highly capable and competitive registrars and registries who have made it possible to reserve or create a new name in just seconds, and to create millions of them per day. Domains are cheap, domains are plentiful, and as a result most of them are dreck or worse. more

Towards a DNSCERT Definition

To mix metaphors, my e-mail has been ringing off the hook after my previous article and I've had to think deep and difficult thoughts about what we really mean by DNSCERT, and whether DNS-OARC really has the capability or really can grow the capability to operate such a thing. I've had some discussions with ICANN and with members of the DNS-OARC board and staff, and it's time I checkpointed the current state of my thinking about all this. more

Perspectives on a DNS-CERT

Last week at the ICANN meeting in Nairobi, a plan was announced by ICANN staff to create a "CERT" for DNS. That's a Community Emergency Response Team (CERT) for the global Domain Name System (DNS). There are all kinds of CERTs in the world today, both inside and outside the Internet industry. There isn't one for DNS, and that's basically my fault, and so I have been following the developments in Nairobi this week very closely. more

Not a Guessing Game

On Tuesday July 8, CERT/CC published advisory #800113 referring to a DNS cache poisoning vulnerability discovered by Dan Kaminsky that will be fully disclosed on August 7 at the Black Hat conference. While the long term fix for this attack and all attacks like it is Secure DNS, we know we can't get the root zone signed, or the .COM zone signed, or the registrar / registry system to carry zone keys, soon enough. So, as a temporary workaround, the affected vendors are recommending that Dan Bernstein's UDP port randomization technique be universally deployed. Reactions have been mixed, but overall, negative. As the coordinator of the combined vendor response, I've heard plenty of complaints, and I've watched as Dan Kaminsky has been called an idiot for how he managed the disclosure. Let me try to respond a little here, without verging into taking any of this personally... more

Why I Am Participating in the ORSN Project

As a long time supporter of the universal namespace operated by IANA, it may come as a surprise that I have joined the Open Root Server Network project (ORSN). I'll try to explain what's going on and what it all means. ...If one of my kids, or anybody anywhere, sits down in front of a web browser and keys in a URL, it ought to just work. They ought to see the same web page that anybody else would see, no matter what country they're in or what their ISP wants or what their local church or government wants. This universality of naming is one of the foundations on which the Internet was built, and it is how the Internet fosters economic growth and social freedoms. It's what makes the Internet different from old Compuserve, old AOL, old MSN, old Minitel, and everything else that has come -- and gone -- before... more

Putting Multiple Root Nameserver Issue to Rest

I am often asked what I think of multiple root nameserver systems -- sort of like the Public-Root or the Open Root Server Confederation (ORSC) pushed by others in the past years. Whenever some well meaning person asks me for multiple roots in DNS, I answer: "DNS is a distributed, coherent, autonomous, hierarchical database. It is defined to have a single root, and every one of the hundreds of millions of DNS-speaking devices worldwide has the single-root design assumptions built into it. It would theoretically be possible to design a new system that looked superficially..." more

Thoughts About “Protection Against BIND”

Imagine my surprise upon reading a BBC article which identified ISC BIND as the top security vulnerability to UNIX systems. At ISC, we have striven for a decade to repair BIND's reputation, and by all accounts we have made great progress. "What could this be about," I wondered, as I scanned the BBC article for more details. It turns out that BBC was merely parroting what it had been told by SANS. OK, let's see what SANS has to say... more

Paul Vixie on Fort N.O.C.‘s

I wish to correct several misstatements made by Brock Meeks in his article, "Fort N.O.C.'s", published January 20. I am speaking as an operator of the "F" root name server which was mentioned several times in this story. ..."A" root is not special in any way. Our "F" root server receives updates from an unrelated server called SRS which is operated under contract from the US Department of Commerce and the Internet Corporation for Assigned Names and Numbers (ICANN). These updates are received by all 13 root name servers, with "A" root a peer of the other 12, having no special capability or importance. If any one of these 13 servers (including "A" root) were temporarily unavailable due to a failure or disaster, there would be no noticeable impact on the Internet as a whole. more

DNS Gets A Formal Coordination System

CircleID recently interview Paul Vixie, Founder & Chairman of Internet Software Consortium (ISC), to discuss ISC's newly formed Operations, Analysis, and Research Center (OARC). OARC is launched in response to DDoS attacks at the Internet's core infrastructure and the vital requirement for a formal coordination system. OARC is also a part of US homeland security initiatives, such as the formation of Information Sharing and Analysis Centers (ISACs).

"Registries and registrars, ccTLD operators, large corporate NOCs, ISPs and ecommerce companies that host many domain names are all likely candidates. This is also a natural for law enforcement groups that are worried about attacks on the Internet." more

Paul Vixie in Response to Site Finder Controversy

As a domain holder myself (of vix.com), I would not have chosen ".com" for my parent domain name back in 1988 had there been a wildcard domain name [that activates Site Finder service] under ".com". The risk of someone attempting to reach me but ending up talking to someone else instead would have been seen as "too great". I am now searching for a new parent domain whose publisher will guarantee me, in perpetuity, that there will be no wildcard name as there now is in "com". more