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RIPE 72 – A Blog Report on DNS & IPv6

Posted by Carsten Strotmann on 6/22/16 5:30 AM

RIPE 72 took place in Copenhagen from 23-27 May 2016. This blog report shares some of my thoughts on interesting talks and presentations on DNS and IPv6.  

As always, this report cannot be exhaustive and I recommend that those interested browse the meeting archive of RIPE 72 for other interesting topics.

DNS

Victoria Risk from ISC reported on the changes in the upcoming BIND 9.11 release (BIND 9.11 Release Update) that is planned for August 2016. The new catalog zone feature allows automatic provisioning of slave zones from a central catalog zone. New zones are configured as a master zone on one server and a special entry is written into the catalog zone, a meta-data zone that is configured on the master and all secondary servers. The catalog zone will be replicated by zone-transfer and the secondary server will automatically configure a slave-zone for the newly added domain.

Men & Mice Trainer Jan-Piet Mens has already had a chance to test this new feature and wrote a blog article about it: Catalog zones in BIND 9.11. ISC has issued an Internet Draft in the IETF about catalog zones with the hope that other DNS software vendors will implement a compatible version.

BIND 9.11 will include a new, refined backend for storing DNS zone data in databases, called the dyndb api. This new API is much faster than the older DLZ API and also works with DNSSEC.

Speaking of DNSSEC, BIND 9.11 will come with a new component called dnssec-keymgr that will be able to automate DNSSEC key-rollover based on a policy, much like the external OpenDNSSEC tool. More improvements to BIND 9.11 can be found in the presentation and also in the upcoming Men & Mice Webinar What's new in BIND 9.11.

Jeff Osborn from ISC started a discussion on a license change of the BIND 9 DNS Server in his talk Changing the Open Source License on BIND. Today, the BIND 9 DNS server is licensed under the ISC license, which is a permissive BSD-style license. Jeff proposes a switch to the Mozilla Public License (MPL), which is a so-called copy-left license. Both licenses are open-source licenses, but the main difference is that the MPL requires all source code changes to the product to be made public. This license change will have no negative effect on anyone using the BIND 9 DNS server, but might affect companies that build products that incorporate the BIND 9 server code. As an overlay management solution, the Men & Mice Suite product works with an un-altered BIND 9, so customers using the Men & Mice Suite would also not be affected by such a license change. Jeff welcomes any feedback on the license change. His contact information can be found in the talk's slides, available in the link above.

Patrik Faltstrom, Chair of the Security and Stability Advisory Committee on the DNS root-server system, presented an alert on WPAD Name Collision Vulnerability. WPAD, the "Web Proxy Auto-Discovery", is a way to configure the Web-Proxy to be used by a Web-Browser using DNS. In this function, the special domain name "wpad" is resolved in the local domain name of the network the client is in. Collisions with internal, non-registered domain names and new top level domains in the Internet DNS system now create the vulnerability that external parties can control the internal proxy configuration inside a company's network. Internet Explorer on Windows systems have this function enabled by default, but it can also be enabled in Firefox, Safari or Chrome-Browsers on MacOS X, BSD and Linux. Running an unregistered TLD in an internal DNS deployment is not recommended, but DNS administrators will find it difficult to remove the sins of the past. Administrators should block DNS queries for internal-only domains at their DNS-resolvers, monitor DNS queries leaving the network for internal names and consider manually switching off the WPAD function in the browsers.

Duane Wessels from Verisign gave a talk on the size increase of the Root-Zone Zone-Signing-Key (ZSK). Since the beginning of the DNSSEC-signed root-zone, the ZSK was a 1024bit RSA key, as recommended by RFC 6781 - DNSSEC Operational Practices, Version 2. However, while not an immediate security threat, 1024bit RSA keys are now also seen as having a too small security margin when used for DNSSEC signatures (1024bit RSA keys have been too weak for encryption for many years). The new ZSK will be a 2048bit key and it will be introduced into the DNS root-zone on 20th September 2016. All testing done so far indicates that there should be no problems. Even though the DNS responses from the root zone during a ZSK rollover do increase from 883 to 1138 octets/bytes, the response is still below the 1232byte EDNS0 limit often used in the IPv6-DNS-Resolver or the 1500byte Ethernet MTU.

The Unbound DNS-Resolver now implements DNS Query Name Minimisation to Improve Privacy, RFC7816. Ralf Dolmans of NLnetLabs explains in his talk QNAME Minimization in Unbound how this new feature is implemented. In traditional DNS, a DNS resolver always asks the full question to all servers in the delegation chain. This is because the DNS resolver does not know about the delegation topology of the DNS system in use. In the Internet, there is a defined delegation structure for DNS, starting with the root-zone, the generic, new and country-code top-level-domains and second-level domains owned by companies and individuals below it. In the Internet, a DNS-resolver can shorten the query when asking at the root-zone or TLD level, enhancing the privacy of the users of the DNS resolver. QNAME minimization in the DNS resolver used by a client machine can be tested with a DNS lookup tool such as dig

 

% dig txt qnamemintest.internet.nl +short


IPv6

John Jason Brzozowski from US cable giant Comcast presented IPv6 @Comcast – Then, Now and Tomorrow about the challenges and successes in their deployment of IPv6 "large scale". Overall, IPv6 at Comcast is a success and they are now putting in motion the plan to phase out IPv4.

In the IPv6-Working-Group session, John reported on Community WiFi and IPv6 and how Comcast is using IPv6 to create public WIFI hotspots on CPE devices. Comcast is giving out a full "/64" network to every WIFI-device connected, in order to create easy network isolation and to reduce the multicast traffic over WLAN. This scheme could have even more benefits, such as assigning an IPv6 address for every service running on a host.

The Google public DNS resolver now supports DNS64-translation (currently in Beta) on the public DNS-resolver address "2001:4860:4860::6464" (IPv6-Only Has Never Been So Easy). DNS64 is a translation technology that works together with NAT64 to allow a client on an IPv6-only network to connect to IPv4-only services on the Internet. As DNS64 "re-writes" DNS content, it clashes with DNSSEC, as Jen Linkova from Google explains in IPv6-only and DNS(SEC|64).The workaround proposed in the talk got some criticism from the audience.

Enno Rey from the security company ERNW had a close look at the security issues of Multicast Listener Discovery MLD, a topic that has not seen much attention so far. He and his colleagues have found several issues that can be used for denial of service attacks or traffic redirection attacks by an intruder inside the local network. He recommends an (still to be developed) "MLD guard" function in switches (similar to DHCPv4- or RA-Guard) or to deploy port based ACL filtering of MLD traffic. Nobody should panic because of these findings, but every IPv6 network admin should know about MLD and the implications of having MLD active in their networks.

Vaibhav Bajpai had an interesting talk on Measuring Webpage Similarity from Dual-Stacked Hosts, looking at the differences in website content between a page fetched via IPv6 vs. IPv4. Differences coming from certain objects on the page (CSS, JavaScript, Advertisements …) are only available for one protocol, while the general website is dual-stacked and therefore available on both IPv4 and IPv6.

Two talks covered the topic of IPv6-only networks, but from very different angles. In How to Make Trouble for Yourself - You Build an IPv6-Only Network in 2016, Roger Jørgensen from Bredbandsfylket Troms in Norway reported on their project to build a new fiber optic network in the far north of Norway. The management part of this network is designed and operated as an IPv6-only network. Luuk Hendriks gave a report of his attempt at Going IPv6-only at Home while keeping the most important user of his home network, his girlfriend, happy.

Enno Rey talks about Real Life Use Cases and Challenges When Implementing Link-local Addressing Only Networks as of RFC 7404 from his experiences implementing a Link-Local-only addressing scheme in a larger enterprise network. The Link-Local-only addressing was chosen to simplify address management, as almost 50% of networks in this customer's environment are point-to-point links. There are still issues with vendor support in network devices when implementing Link-Local-only addressing. In the discussion following the talk, the audience gave a mixed message, with some people claiming success at running a Link-Local-only network.

Other topics

Mircea Ulinic presented a way to automate the provisioning and management of network devices (router, switches etc) using the configuration orchestration tool "SaltStack". SaltStack is usually used to automate the provisioning of server machines running a Salt-Agent (Minion). As it is difficult to install a customer agent on network gear, this talk presented a way to use proxy machines that act as the minions for network hardware. SaltStack automation can save a great deal of time when used in large deployments. Details can be found in Mircea's talk: Network Automation with Salt and NAPALM.

Shane Kerr, who we recently had as an interview guest in our latest Webinar on Yeti-DNS, gave a humorous talk about the "Internet of Things (IoT)" in IoT: What is the Problem or “How To Explain To Your Boss That IoT Won't Make the Company Rich….”.

Those of you hungry for more on RIPE 72, all the above talks and more can be found in the meeting archive of RIPE 72.

Topics: IPv6, DNSSEC, DNS

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