Tag: modeling

Categories
Papers Publications

new conference paper “Connection-Oriented DNS to Improve Privacy and Security” in Oakland 2015

The paper “Connection-Oriented DNS to Improve Privacy and Security” will appear at the 36th IEEE Symposium on Security and Privacy in May 2015 in San Jose, CA, USA  (available at http://www.isi.edu/~liangzhu/papers/Zhu15b.pdf)

From the abstract:end_to_end_model_n_7

The Domain Name System (DNS) seems ideal for connectionless UDP, yet this choice results in challenges of eavesdropping that compromises privacy, source-address spoofing that simplifies denial-of-service (DoS) attacks on the server and third parties, injection attacks that exploit fragmentation, and reply-size limits that constrain key sizes and policy choices. We propose T-DNS to address these problems. It uses TCP to smoothly support large payloads and to mitigate spoofing and amplification for DoS. T-DNS uses transport-layer security (TLS) to provide privacy from users to their DNS resolvers and optionally to authoritative servers. TCP and TLS are hardly novel, and expectations about DNS suggest connections will balloon client latency and overwhelm server with state. Our contribution is to show that T-DNS significantly improves security and privacy: TCP prevents denial-of-service (DoS) amplification against others, reduces the effects of DoS on the server, and simplifies policy choices about key size. TLS protects against eavesdroppers to the recursive resolver. Our second contribution is to show that with careful implementation choices, these benefits come at only modest cost: end-to-end latency from TLS to the recursive resolver is only about 9% slower when UDP is used to the authoritative server, and 22% slower with TCP to the authoritative. With diverse traces we show that connection reuse can be frequent (60–95% for stub and recursive resolvers, although half that for authoritative servers), and after connection establishment, experiments show that TCP and TLS latency is equivalent to UDP. With conservative timeouts (20 s at authoritative servers and 60 s elsewhere) and estimated per-connection memory, we show that server memory requirements match current hardware: a large recursive resolver may have 24k active connections requiring about 3.6 GB additional RAM. Good performance requires key design and implementation decisions we identify: query pipelining, out-of-order responses, TCP fast-open and TLS connection resumption, and plausible timeouts.

The work in the paper is by Liang Zhu, Zi Hu and John Heidemann (USC/ISI), Duane Wessels and Allison Mankin (both of Verisign Labs), and Nikita Somaiya (USC/ISI).  Earlier versions of this paper were released as ISI-TR-688 and ISI-TR-693; this paper adds results and supercedes that work.

The data in this paper is available to researchers at no cost on request. Please see T-DNS-experiments-20140324 at dataset page.

Categories
Papers Publications

new conference paper “BotTalker: Generating Encrypted, Customizable C&C Traces” in HST 2015

The paper “BotTalker: Generating Encrypted, Customizable C&C Traces” will appear at the 14th annual IEEE Symposium on Technologies for Homeland Security (HST ’15) in April 2015 (available at http://www.cs.colostate.edu/~zhang/papers/BotTalker.pdf)

From the abstract:

Encrypted botnets have seen an increasingalerts-types-breakdown-originaluse  in recent years. To enable research in detecting encrypted botnets researchers need samples of encrypted botnet traces with ground truth, which are very hard to get. Traces that are available are not customizable, which prevents testing under various controlled scenarios. To address this problem we introduce BotTalker, a tool that can be used to generate customized encrypted botnet communication traffic. BotTalker emulates the actions a bot would take to encrypt communication. It includes a highly configurable encrypted-traffic converter along with real, non- encrypted bot traces and background traffic. The converter is able to convert non-encrypted botnet traces into encrypted ones by providing customization along three dimensions: (a) selection of real encryption algorithm, (b) flow or packet level conversion, SSL emulation and (c) IP address substitution. To the best of our knowledge, BotTalk is the first work that provides users customized encrypted botnet traffic. In the paper we also apply BotTalker to evaluate the damage result from encrypted botnet traffic on a widely used botnet detection system – BotHunter and two IDS’ – Snort and Suricata. The results show that encrypted botnet traffic foils bot detection in these systems.

This work is advised by Christos Papadopoulos and supported by LACREND.

Categories
Presentations

new talk “Internet Populations (Good and Bad): Measurement, Estimation, and Correlation” at the ICERM Workshop on Cybersecurity

John Heidemann gave the talk “Internet Populations (Good and Bad): Measurement, Estimation, and Correlation” at the ICERM Workshop on Cybersecurity at Brown University, Providence, Rhode Island on October 22, 2014. Slides are available at http://www.isi.edu/~johnh/PAPERS/Heidemann14e/.

Can we improve the mathematical tools we use to measure and understand the Internet?
Can we improve the mathematical tools we use to measure and understand the Internet?

From the abstract:

Our research studies the Internet’s public face. Since 2006 we have been taking censuses of the Internet address space (pinging all IPv4 addresses) every 3 months. Since 2012 we have studied network outages and events like Hurricane Sandy, using probes of much of the Internet every 11 minutes. Most recently we have evaluated the diurnal Internet, finding countries where most people turn off their computers at night. Finally, we have looked at network reputation, identifying how spam generation correlates with network location, and others have studies multiple measurements of “network reputation”.

A common theme across this work is one must estimate characteristics of the edge of the Internet in spite of noisy measurements and a underlying changes. One also need to compare and correlate these imperfect measurements with other factors (from GDP to telecommunications policies).

How do these applications relate to the mathematics of census taking and measurement, estimation, and correlation? Are there tools we should be using that we aren’t? Do the properties of the Internet suggest new approaches (for example where rapid full enumeration is possible)? Does correlation and estimates of network “badness” help us improve cybersecurity by treating different parts of the network differently?

Categories
Papers Publications

new conference paper “When the Internet Sleeps: Correlating Diurnal Networks With External Factors” in IMC 2014

The paper “When the Internet Sleeps: Correlating Diurnal Networks With External Factors” will appear at ACM Internet Measurements Conference 2014 in Vancouver, Canada (available at http://www.isi.edu/~johnh/PAPERS/Quan14c/ with cite and pdf, or direct pdf).

Predicting longitude from observed diurnal phase ([Quan14c], figure 14c)
Predicting longitude from observed diurnal phase for 287k geolocatable, diurnal blocks ([Quan14c], figure 14c)
From the abstract:

As the Internet matures, policy questions loom larger in its operation. When should an ISP, city, or government invest in infrastructure? How do their policies affect use? In this work, we develop a new approach to evaluate how policies, economic conditions and technology correlates with Internet use around the world. First, we develop an adaptive and accurate approach to estimate block availability, the fraction of active IP addresses in each /24 block over short timescales (every 11 minutes). Our estimator provides a new lens to interpret data taken from existing long-term outage measurements, thus requiring no additional traffic. (If new collection was required, it would be lightweight, since on average, outage detection requires less than 20 probes per hour per /24 block; less than 1% of background radiation.) Second, we show that spectral analysis of this measure can identify diurnal usage: blocks where addresses are regularly used during part of the day and idle in other times. Finally, we analyze data for the entire responsive Internet (3.7M /24 blocks) over 35 days. These global observations show when and where the Internet sleeps—networks are mostly always-on in the US and Western Europe, and diurnal in much of Asia, South America, and Eastern Europe. ANOVA (Analysis of Variance) testing shows that diurnal networks correlate negatively with country GDP and electrical consumption, quantifying that national policies and economics relate to networks.

Citation: Lin Quan, John Heidemann, and Yuri Pradkin. When the Internet Sleeps: Correlating Diurnal Networks With External Factors. In Proceedings of the ACM Internet Measurement Conference, p. to appear. Vancouver, BC, Canada, ACM. November, 2014.

All data in this paper is available to researchers at no cost, and source code to our analysis tools is available on request; see our diurnal datasets webpage.

This work is partly supported by DHS S&T, Cyber Security division, agreement FA8750-12-2-0344 (under AFRL) and N66001-13-C-3001 (under SPAWAR).  The views contained
herein are those of the authors and do not necessarily represent those of DHS or the U.S. Government.  This work was classified by USC’s IRB as non-human subjects research (IIR00001648).

Categories
Publications Technical Report

new technical report “T-DNS: Connection-Oriented DNS to Improve Privacy and Security (extended)”

We released a new technical report “T-DNS: Connection-Oriented DNS to Improve Privacy and Security (extended)”, ISI-TR-2014-693, available as http://www.isi.edu/~johnh/PAPERS/Zhu14b.pdf

From the abstract:resp_cdf_diff_key_all

DNS is the canonical protocol for connectionless UDP. Yet DNS today is challenged by eavesdropping that compromises privacy, source-address spoofing that results in denial-of-service (DoS) attacks on the server and third parties, injection attacks that exploit fragmentation, and size limitations that constrain policy and operational choices. We propose T-DNS to address these problems. It uses TCP to smoothly support large payloads and to mitigate spoofing and amplification for DoS. T-DNS uses transport-layer security (TLS) to provide privacy from users to their DNS resolvers and optionally to authoritative servers. Expectations about DNS suggest connections will balloon client latency and overwhelm server with state, but our evaluation shows costs are modest: end-to-end latency from TLS to the recursive resolver is only about 9% slower when UDP is used to the authoritative server, and 22% slower with TCP to the authoritative. With diverse traces we show that frequent connection reuse is possible (60–95% for stub and recursive resolvers, although half that for authoritative servers), and after connection establishment, we show TCP and TLS latency is equivalent to UDP. With conservative timeouts (20 s at authoritative servers and 60 s elsewhere) and conservative estimates of connection state memory requirements, we show that server memory requirements match current hardware: a large recursive resolver may have 24k active connections requiring about 3.6 GB additional RAM. We identify the key design and implementation decisions needed to minimize overhead: query pipelining, out-of-order responses, TLS connection resumption, and plausible timeouts.

This paper is a major revision of the prior technical report ISI-TR-2014-688. Since that work we have improved our understanding of the availability of TCP fast open and TLS resumption, and we have tightened our estimates on memory based on external reports (section 5.2). This additional information has allowed us to conduct additional experiments, improve our modeling, and provide a more accurate view of what is possible today; our estimates of latency and memory consumption are both lower than in our prior technical report as a result. We have also added additional information about packet size limitations (Figure 2), experiments evaluating DNSCrypt/DNSCurve (section 6.1), analysis of DTLS, and covered a broader range of RTTs in our experiments. We believe these additions strengthen our central claims: that connectionless DNS causes multiple problems and that T-DNS addresses those problems with modest increase in latency and memory suitable for current hardware.

Categories
Publications Technical Report

new technical report “When the Internet Sleeps: Correlating Diurnal Networks With External Factors (extended)”

We released a new technical report “When the Internet Sleeps: Correlating Diurnal Networks With External Factors (extended)”, ISI-TR-2014-691, by Lin Quan, John Heidemann, and Yuri Pradkin, available as http://www.isi.edu/~johnh/PAPERS/Quan14b.
pdf

Comparing observed diurnal phase and geolocation longitude for 287k geolocatable, diurnal blocks ([Quan14b], figure 14b)
Comparing observed diurnal phase and geolocation longitude for 287k geolocatable, diurnal blocks ([Quan14b], figure 14b)
From the abstract:

As the Internet matures, policy questions loom larger in its operation. When should an ISP, city, or government invest in infrastructure? How do their policies affect use? In this work, we develop a new approach to evaluate how policies, economic conditions and technology correlates with Internet use around the world. First, we develop an adaptive and accurate approach to estimate block availability, the fraction of active IP addresses in each /24 block over short timescales (every 11 minutes). Our estimator provides a new lens to interpret data taken from existing long-term outage measurements, this requiring no no additional traffic. (If new collection was required, it would be lightweight, since on average, outage detection requires less than 20 probes per hour per /24 block; less than 1% of background radiation.) Second, we show that spectral analysis of this measure can identify diurnal usage: blocks where addresses are regularly used during part of the day and idle in other times. Finally, we analyze data for the entire responsive Internet (3.7M /24 blocks) over 35 days. These global observations show when and where the Internet sleeps—networks are mostly always-on in the US and Western Europe, and diurnal in much of Asia, South America, and Eastern Europe. ANOVA testing shows that diurnal networks correlate negatively with country GDP and electrical consumption, quantifying that national policies and economics relate to networks.

Data from this paper is available from http://www.isi.edu/ant/traces/internet_otuages/index.html, and from http://www.predict.org as dataset internet_outage_adaptive_a12w-20130424.

Categories
Presentations

new talk “T-DNS: Connection-Oriented DNS to Improve Privacy and Security” given at DNS-OARC

John Heidemann gave the talk “T-DNS: Connection-Oriented DNS to Improve Privacy and Security” given at the Spring DNS-OARC meeting in Warsaw, Poland on May 10, 2014.  Slides are available at http://www.isi.edu/~johnh/PAPERS/Heidemann14c.html.

don't fear connections for DNS
don’t fear connections for DNS

From the abstract:

This talk will discuss connection-oriented DNS to improve DNS security and privacy. DNS is the canonical example of a connectionless, single packet, request/response protocol, with UDP as its dominant transport. Yet DNS today is challenged by eavesdropping that compromises privacy, source-address spoofing that results in denial-of-service (DoS) attacks on the server and third parties, injection attacks that exploit fragmentation, and size limitations that constrain policy and operational choices. We propose t-DNS to address these problems: it uses TCP to smoothly support large payloads and mitigate spoofing and amplification for DoS. T-DNS uses transport-layer security (TLS) to provide privacy from users to their DNS resolvers and optionally to authoritative servers.

Traditional wisdom is that connection setup will balloon latency for clients and overwhelm servers. We provide data to show that these assumptions are overblown–our model of end-to-end latency shows TLS to the recursive resolver is only about 5-24% slower, with UDP to the authoritative server. End-to-end latency is 19-33% slower with TLS to recursive and TCP to authoritative. Experiments behind these models show that after connection establishment, TCP and TLS latency is equivalent to UDP. Using diverse trace data we show that frequent connection reuse is possible (60-95% for stub and recursive resolvers, although half that for authoritative servers). With conservative timeouts (20 s at authoritative servers and 60 s elsewhere) we show that : a large recursive resolver may have 25k active connections consuming about 9 GB of RAM. These results depend on specific design and implementation decisions–query pipelining, out-of-order responses, TLS connection resumption, and plausible timeouts.

We hope to solicit feedback from the OARC community about this work to understand design and operational concerns if T-DNS deployment was widespread. The work in the talk is by Liang Zhu, Zi Hu, and John Heidemann (all of USC/ISI), Duane Wessels and Allison Mankin (both of Verisign), and Nikita Somaiya (USC/ISI).

A technical report describing the work is at http://www.isi.edu/ johnh/PAPERS/Zhu14a.pdf and the protocol changes are described ashttp://datatracker.ietf.org/doc/draft-hzhwm-start-tls-for-dns/.

Categories
Publications Technical Report

new technical report “T-DNS: Connection-Oriented DNS to Improve Privacy and Security”

We released a new technical report “T-DNS: Connection-Oriented DNS to Improve Privacy and Security”, ISI-TR-2014-688, available as http://www.isi.edu/~johnh/PAPERS/Zhu14a.pdf

 

From the abstract:sim_hit_server_median_all

This paper explores connection-oriented DNS to improve DNS security and privacy. DNS is the canonical example of a connectionless, single packet, request/response protocol, with UDP as its dominant transport. Yet DNS today is challenged by eavesdropping that compromises privacy, source-address spoofing that results in denial-of-service (DoS) attacks on the server and third parties, injection attacks that exploit fragmentation, and size limitations that constrain policy and operational choices. We propose t-DNS to address these problems: it combines TCP to smoothly support large payloads and mitigate spoofing and amplification for DoS. T-DNS uses transport-layer security (TLS) to provide privacy from users to their DNS resolvers and optionally to authoritative servers. Traditional wisdom is that connection setup will balloon latency for clients and overwhelm servers. These are myths—our model of end-to-end latency shows TLS to the recursive resolver is only about 21% slower, with UDP to the authoritative server. End-to-end latency is 90% slower with TLS to recursive and TCP to authoritative. Experiments behind these models show that after connection establishment, TCP and TLS latency is equivalent to UDP. Using diverse trace data we show that frequent connection reuse is possible (60–95% for stub and recursive resolvers, although half that for authoritative servers). With conservative timeouts (20 s at authoritative servers and 60 s elsewhere) we show that server memory requirements match current hardware: a large recursive resolver may have 25k active connections consuming about 9 GB of RAM. We identify the key design and implementation decisions needed to minimize overhead—query pipelining, out-of-order responses, TLS connection resumption, and plausible timeouts.

 

Categories
Papers Publications

new conference paper “The Need for End-to-End Evaluation of Cloud Availability” in PAM 2014

The paper “The Need for End-to-End Evaluation of Cloud Availability” was published by PAM 2014 in Marina del Rey, CA (available at http://www.isi.edu/~zihu/paper/cloud_availability.pdf).

From the abstract:cloud_availability_blog

People’s computing lives are moving into the cloud, making understanding cloud availability increasingly critical. Prior studies of Internet outages have used ICMP-based pings and traceroutes. While these studies can detect network availability, we show that they can be inaccurate at estimating cloud availability. Without care, ICMP probes can underestimate availability because ICMP is not as robust as application-level measurements such as HTTP. They can overestimate availability if they measure reachability of the cloud’s edge, missing failures in the cloud’s back-end. We develop methodologies sensitive to five “nines” of reliability, and then we compare ICMP and end-to-end measurements for both cloud VM and storage services. We show case studies where one fails and the other succeeds, and our results highlight the importance of application-level retries to reach high precision. When possible, we recommend end-to-end measurement with application-level protocols to evaluate the availability of cloud services.

Citation: Zi Hu, Liang Zhu, Calvin Ardi, Ethan Katz-Bassett, Harsha Madhyastha, John Heidemann, Minlan Yu. The Need for End-to-End Evaluation of Cloud Availability. Passive and Active Measurements Conference (PAM). Los Angeles, CA, USA, March 2014.

Categories
Students

congratulations to Lin Quan for his new PhD

I would like to congratulate Dr. Lin Quan for defending his PhD in Dec. 2013 and his doctoral disseration “Learning about the Internet through Efficient Sampling and Aggregation” in Jan. 2014.

Lin Quan (left) and John Heidemann, after Lin's PhD defense.
Lin Quan (left) and John Heidemann, after Lin’s PhD defense.

From the abstract:

The Internet is important for nearly all aspects of our society, affecting ordinary people, businesses, and social activities. Because of its importance and wide-spread applications, we want to have good knowledge about Internet’s operation, reliability and performance, through various kinds of measurements. However, despite the wide usage, we only have limited knowledge of its overall performance and reliability. The first reason of this limited knowledge is that there is no central governance of the Internet, making both active and passive measurements hard. The second reason is the huge scale of the Internet. This makes brute-force analysis hard because of practical computing resource limits such as CPU, memory and probe rate.

This thesis states that sampling and aggregation are necessary to overcome resource constraints in time and space to learn about better knowledge of the Internet. Many other Internet measurement studies also utilize sampling and aggregation techniques to discover properties of the Internet. We distinguish our work by exploring novel mechanisms and new knowledge in several specific areas. First, we aggregate short-time-scale observations and use an efficient multi-time-scale query scheme to discover the properties and reasons of long-lived Internet flows. Second, we sample and probe /24 blocks in the IPv4 address space, and use greedy clustering algorithms to efficiently characterize Internet outages. Third, we show an efficient and effective aggregation technique by visualization and clustering. This technique makes both manual inspection and automated characterization easier. Last, we develop an adaptive probing system to study global scale Internet reliability. It samples and adapts probe rate within each /24 block for accurate beliefs. By aggregation and correlation to other domains, we are also able to study broader policy effects on Internet use, such as political causes, economic conditions, and access technologies.

This thesis provides several examples of Internet knowledge discovery with new mechanisms of sampling and aggregation techniques. We believe our approaches of new sampling and aggregation mechanisms can be used by and will inspire new ways for future Internet measurement systems to overcome resource constraints, such as large amount and dispersed data.