Performance Comparison of Routing Protocols in Bipartite Wireless Sensor Network

This paper evaluates and ranks the suitability of routing algorithms for bipartite wireless sensor network topology. The network considered in this paper, consists of an irregular combination of fixed and mobile nodes, which leads to construction of a bipartite graph among them. A wireless sensor network is usually constrained by the energy limitations and processing capabilities. We therefore, consider the important metrics for analysis namely, carried load, energy consumption and the average delay incurred. We present the possibilities of employing the routing algorithms subject to the quality of service required by the wireless sensor networks application

Few Throats to Choke: On the Current Structure of the Internet

The original design of the Internet was as a resilient, distributed system, able to route around (and therefore recover from) massive disruption - up to and including nuclear war. However, network effects and business decisions (e.g. the pur- chase of GlobalCrossing by Level-3) have led to centralization of routing power. This is not merely an academic issue; it has practical implications, such as whether the citizens of a country may be subject to censorship by an “upstream” ISP in some other country, that controls its entire access to the Internet. In this paper, we examine the extent of routing centralization in the Internet; identify the major players who control the “Internet backbone”; and point out how many these are, in fact, under the jurisdiction of censorious countries. We also measure the collateral damage caused by censorship, particularly by the two largest Internet-using nations, China and India

Aroma Tells a Thousand Pictures: Digital Scent Technology a New Chapter in IT Industry

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PTPerf: On the performance evaluation of Tor Pluggable Transports

Tor, one of the most popular censorship circumvention systems, faces regular blocking attempts by censors. Thus, to facilitate access, it relies on "pluggable transports" (PTs) that disguise Tor's traffic and make it hard for the adversary to block Tor. However, these are not yet well studied and compared for the performance they provide to the users. Thus, we conduct a first comparative performance evaluation of a total of 12 PTs -- the ones currently supported by the Tor project and those that can be integrated in the future. Our results reveal multiple facets of the PT ecosystem. (1) PTs' download time significantly varies even under similar network conditions. (2) All PTs are not equally reliable. Thus, clients who regularly suffer censorship may falsely believe that such PTs are blocked. (3) PT performance depends on the underlying communication primitive. (4) PTs performance significantly depends on the website access method (browser or command-line). Surprisingly, for some PTs, website access time was even less than vanilla Tor. Based on our findings from more than 1.25M measurements, we provide recommendations about selecting PTs and believe that our study can facilitate access for users who face censorship.Comment: 25 pages, 12 figure

Mending Wall: On the Implementation of Censorship in India

This paper presents a study of the Internet infrastructure in India from the point of view of censorship. First, we show that the current state of affairs — where each ISP implements its own content filters (nominally as per a governmental blacklist) — results in dramatic differences in the censorship experienced by customers. In practice, a well-informed Indian citizen can escape censorship through a judicious choice of service provider. We then consider the question of whether India might potentially follow the Chinese model and institute a single, government-controlled filter. This would not be difficult, as the Indian Internet is quite centralized already. A few “key” ASes (≈ 1% of Indian ASes) collectively intercept ≈ 95% of paths to the censored sites we sample in our study, and also to all publicly-visible DNS servers. 5, 000 routers spanning these key ASes would suffice to carry out IP or DNS filtering for the entire country; ≈ 70% of these routers belong to only two private ISPs. If the government is willing to employ more powerful measures, such as an IP Prefix Hijacking attack, any one of several key ASes can censor traffic for nearly all Indian users. Finally, we demonstrate that such federated censorship by India would cause substantial collateral damage to non-Indian ASes whose traffic passes through Indian cyberspace (which do not legally come under Indian jurisdiction at all)

How India Censors the Web

One of the primary ways in which India engages in online censorship is by ordering Internet Service Providers (ISPs) operating in its jurisdiction to block access to certain websites for its users. This paper reports the different techniques Indian ISPs are using to censor websites, and investigates whether website blocklists are consistent across ISPs. We propose a suite of tests that prove more robust than previous work in detecting DNS and HTTP based censorship. Our tests also discern the use of SNI inspection for blocking websites, which is previously undocumented in the Indian context. Using information from court orders, user reports, and public and leaked government orders, we compile the largest known list of potentially blocked websites in India. We pass this list to our tests and run them from connections of six different ISPs, which together serve more than 98% of Internet users in India. Our findings not only confirm that ISPs are using different techniques to block websites, but also demonstrate that different ISPs are not blocking the same websites