Month: May 2016

Categories
Publications Technical Report

new technical report “Anycast vs. DDoS: Evaluating the November 2015 Root DNS Event”

We have released a new technical report “Anycast vs. DDoS: Evaluating the November 2015 Root DNS Event”, ISI-TR-2016-709, available at http://www.isi.edu/~johnh/PAPERS/Moura16a.pdf

From the abstract:

[Moura16a] Figure 3
[Moura16a] Figure 3: reachability at several root letters (anycast instances) during two events with very heavy traffic.

Distributed Denial-of-Service (DDoS) attacks continue to be a major threat in the Internet today. DDoS attacks overwhelm target services with requests or other traffic, causing requests from legitimate users to be shut out. A common defense against DDoS is to replicate the service in multiple physical locations or sites. If all sites announce a common IP address, BGP will associate users around the Internet with a nearby site,defining the catchment of that site. Anycast addresses DDoS both by increasing capacity to the aggregate of many sites, and allowing each catchment to contain attack traffic leaving other sites unaffected. IP anycast is widely used for commercial CDNs and essential infrastructure such as DNS, but there is little evaluation of anycast under stress. This paper provides the first evaluation of several anycast services under stress with public data. Our subject is the Internet’s Root Domain Name Service, made up of 13 independently designed services (“letters”, 11 with IP anycast) running at more than 500 sites. Many of these services were stressed by sustained traffic at 100 times normal load on Nov.30 and Dec.1, 2015. We use public data for most of our analysis to examine how different services respond to the these events. We see how different anycast deployments respond to stress, and identify two policies: sites may absorb attack traffic, containing the damage but reducing service to some users, or they may withdraw routes to shift both good and bad traffic to other sites. We study how these deployments policies result in different levels of service to different users. We also show evidence of collateral damage on other services located near the attacks.

This technical report is joint work of  Giovane C. M. Moura, Moritz Müller, Cristian Hesselman(SIDN Labs), Ricardo de O. Schmidt, Wouter B. de Vries (U. Twente), John Heidemann, Lan Wei (USC/ISI). Datasets in this paper are derived from RIPE Atlas and are available at http://traces.simpleweb.org/ and at https://ant.isi.edu/datasets/.

Categories
Announcements In-the-news

new RFC “Specification for DNS over Transport Layer Security (TLS)”

The Internet RFC-7858, “Specification for DNS over Transport Layer Security (TLS)”, was just released by the ITEF as a Standards Track document.

From the abstract:

This document describes the use of Transport Layer Security (TLS) to provide privacy for DNS. Encryption provided by TLS eliminates opportunities for eavesdropping and on-path tampering with DNS queries in the network, such as discussed in RFC 7626. In addition, this document specifies two usage profiles for DNS over TLS and provides advice on performance considerations to minimize overhead from using TCP and TLS with DNS.

This document focuses on securing stub-to-recursive traffic, as per
the charter of the DPRIVE Working Group. It does not prevent future applications of the protocol to recursive-to-authoritative traffic.

This RFC is joint work of Zhi Hu, Liang Zhu, John Heidemann, Allison Mankin, Duane Wessels, and Paul Hoffman, of USC/ISI, Verisign, ICANN, and independent (at different times).  This RFC is one result of our prior paper “Connection-Oriented DNS to Improve Privacy and Security”, but also represents the input of the DPRIVE IETF working group (Warren Kumari and Tim Wicinski, chairs), where it is one of a set of RFCs designed to improve DNS privacy.

On to deployments!

Categories
Publications Technical Report

new technical report “Anycast Latency: How Many Sites Are Enough?”

We have released a new technical report “Anycast Latency: How Many Sites Are Enough?”, ISI-TR-2016-708, available at http://www.isi.edu/%7ejohnh/PAPERS/Schmidt16a.pdf.

[Schmidt16a] figure 4: distribution of measured latency (solid lines) to optimal possible latency (dashed lines) for 4 Root DNS anycast deployments.
[Schmidt16a] figure 4: distribution of measured latency (solid lines) to optimal possible latency (dashed lines) for 4 Root DNS anycast deployments.
From the abstract:

Anycast is widely used today to provide important services including naming and content, with DNS and Content Delivery Networks (CDNs). An anycast service uses multiple sites to provide high availability, capacity and redundancy, with BGP routing associating users to nearby anycast sites. Routing defines the catchment of the users that each site serves. Although prior work has studied how users associate with anycast services informally, in this paper we examine the key question how many anycast sites are needed to provide good latency, and the worst case latencies that specific deployments see. To answer this question, we must first define the optimal performance that is possible, then explore how routing, specific anycast policies, and site location affect performance. We develop a new method capable of determining optimal performance and use it to study four real-world anycast services operated by different organizations: C-, F-, K-, and L-Root, each part of the Root DNS service. We measure their performance from more than worldwide vantage points (VPs) in RIPE Atlas. (Given the VPs uneven geographic distribution, we evaluate and control for potential bias.) Key results of our study are to show that a few sites can provide performance nearly as good as many, and that geographic location and good connectivity have a far stronger effect on latency than having many nodes. We show how often users see the closest anycast site, and how strongly routing policy affects site selection.

This technical report is joint work of Ricardo de O. Schmidt and Jan Harm Kuipers (U. Twente) and John Heidemann (USC/ISI).  Datasets in this paper are derived from RIPE Atlas and are available at http://traces.simpleweb.org/.