p2pnet news view Freedom | P2P:- The practice of controlling, or trying to control, information and data can take many shapes and forms.

CXXXXa’s leaders used to be pre-eminent in believing they could cxxxxx what their people sxx and don’t sxx, dx and don’t dx.

However, now AXXXXXXXX’s Labour government seems determined to join CXXXX, and one might also suggest NXXX ZXXXXXXand FXXXXXX, seemingly about to pass laws to force local ISPs to act as corporate copyright enforcers,  are also on the verge of becoming prime Net censorship countries.

And, “On Sunday, 24 February 2008, Pakistan Telecom (AS17557) started an unauthorised announcement of the prefix 208.65.153.0/24,” said RIPE NCC’s Routing Information Service (RIS).

“One of Pakistan Telecom’s upstream providers, PCCW Global (AS3491) forwarded this announcement to the rest of the Internet, which resulted in the hijacking of YouTube traffic on a global scale.”

The Pakistan hijacking  was sharp, but short. What, however, would happen if one company consciously set out to influence traffic in another?

“The treatment of Internet traffic is increasingly affected by national policies that require the ISPs in a country to adopt common protocols or practices,” say Josh Karlin (University of New Mexico), Stephanie Forrest (University of New Mexico and the Santa Fe Institute), Jennifer Rexford (Princeton University) in a new paper.

“Examples include government enforced censorship, wiretapping, and protocol deployment mandates for IPv6 and DNSSEC,” they say, but, “If an entire nation’s worth of ISPs apply common policies to Internet traffic, the global implications could be significant.”

In their abstract to Nation-State Routing: Censorship, Wiretapping, and BGP, they go on »»»

For instance, how many countries rely on China or Great Britain (known traffic censors) to transit their traffic? These kinds of questions are surprisingly difficult to answer, as they require combining information collected at the prefix, Autonomous System, and country level, and grappling with incomplete knowledge about the AS-level topology and routing policies. In this paper we develop the first framework for country-level routing analysis, which allows us to answer questions about the influence of each country on the flow of international traffic.

Our results show that some countries known for their national policies, such as Iran and China, have relatively little effect on interdomain routing, while three countries (the United States, Great Britain, and Germany) are central to international reachability, and their policies thus have huge potential impact.

And as government control over the treatment of online traffic becomes more common, “many people will want to understand how international reachability depends on individual countries and to adopt strategies either for enhancing or weakening the dependence on some countries,” say  Karlin, Forrest and Rexford.

“The work presented in this paper is an initial step towards providing the algorithms and tools that will be needed to understand and manage nation-state routing,” they state, adding:

“It is not surprising that the results show the dominance of the US at the country routing level.

“However, other countries appear to have either more or less importance than one might expect. For example, both Great Britain and Germany are second only to the U.S. in centrality, while Japan, China, and India are only 8th, 10th, and 32nd respectively. Collectively, these results show that the West continues to exercise disproportionate influence over international routing, despite the penetration of the Internet to almost every region of the world, and the rapid development of China and India. Beyond what the results tell us about the Internet today, we see the methods described in this paper as helping network designers, policy makers, and researchers better understand the likely impact of national policies on user privacy and the access to politically or socially sensitive content.”

Below is the introduction to Nation-State Routing: Censorship, Wiretapping, and BGP »»»

Internet routing is typically studied at the Autonomous System (AS) level. This is by design. Traditionally, ASes control their own internal networks and set their own policies for the routing, filtering, and monitoring of traffic, placing policy in the hands of the organizations that own them. Recently, groups of ASes have begun to act under common policies, issued by their country’s government. Examples include Internet cen- sorship, wiretapping, and protocol-deployment mandates. For instance, Chinese, British, and Pakistani ISPs are required (or strongly encouraged) to filter content deemed socially offensive. Although censoring techniques differ, all three countries are known to block traffic at the IP level (e.g., by filtering based onIP addresses and URLs in the data packets, or performing internal prefix hijacks [5, 6, 7]), which could affectthe international traffic they transit. Some countries, such as the United States and Sweden, wiretap international traffic, where even encrypted traffic is vulnerable to traffic-analysis attacks [8]. Finally, governments can attempt to force the deployment of protocols, such as the deployment of IPv6 and DNSSEC in federal agencies of the United States.

It is unclear what effect any particular country’s policies have on the rest of the Internet. Typically, censorship is applied to prevent domestic users from reaching disagreeable content. However, some censorship techniques (such as filtering based on IP addresses or URLs) may affect all traffic traversing an AS. In addition, ASes might intentionally, or accidentally as in the recent YouTube outage [6], apply censorship policies to international traffic. How many networks outside of the country would be prevented from viewing Web pages simply because their traffic traverses one of these networks? Which international traffic is vulnerable to warrantless wiretapping by the United States or Sweden? And, finally, how feasible is it to avoid directing traffic through a given country with objectionable policies by using alternative routes?

To answer these questions, we must study the aggregate effect of national policies on the flow of international traffic, rather than analyzing individual ASes in isolation. In this paper we take initial steps toward understanding interdomain routing at the nation-state level. We are particularly interested in understanding the in uence that each country’s ASes have over reachability between other countries. The resulting data and measurement techniques could be useful to many communities. First, those regions of the world with strong dependencies on particular countries could use our result to guide changes in how they connect to the rest of the Internet. Second, overlay networks (such as Resilient Overlay Networks) could use our results to determine how best to circumvent specific countries, helping to ensure that data are delivered intact, and avoid snooping. Third, our results would be helpful to policy makers to understand what impact their decisions could have on the global Internet.

There are two primary challenges in this work. The first is to determine suitable metrics for quantifying the importance, or centrality, of each country to Internet reachability. The second is to accurately infer the data needed to compute these metrics, and validate them.
We adapt the betweenness centrality metric from statistical physics as a first approximation of country centrality. Betweenness centrality is typically used as a native traffic estimator at each node in a graph. We adapt betweenness centrality to estimate the impact each country has on reachability between other countries, determining country centrality (CC) in Section 4.

Our metrics take as input the country-level paths between each pair of IP addresses in the Internet. This is a significant challenge because of the many levels of inference required to produce a country-level interdomain path. First, ASes select routes using the Border Gateway Protocol (BGP), which chooses routes based on undisclosed routing policies, rather than simply using the shortest path. Fortunately, this is a well-studied problem and several inference algorithms exist for inferring AS-level routes. A second challenge arises because an individual AS may span many countries. This leads us to consider routing at the IP prefix level, which re- quires understanding how packets traverse each AS. Finally, each path must be converted to a country-level path by mapping IP addresses to prefixes, and then prefixes to countries (e.g., using routing registry data).

There is a risk of introducing significant, and possibly compounding, error in each step of the process. However, we present empirical evidence to suggest that our centrality metric is robust to the measurement noise, and that our results are meaningful. Our inference techniques allow us to estimate the centrality of each country, where CC values range from 0 (implying no influence) to 1 (the theoretical maximum).

Our results show that countries known for censorship, such as Great Britain, China, Australia, and Iran, have CC values of 0.29, 0.07, 0.07, and 1.12e-05 respectively.

These results suggest that, of the countries that censor Internet traffic, only some have significant impact on global routing. In particular, the countries that have received the most publicity for their censorship, such as China, have significantly less impact on international traffic than, say, Great Britain, which also censors traffic. We also show that the United States and Sweden (nations known to permit warrantless wiretapping) have CC values of 0.74 and 0.02; even if ASes actively prefer BGP routes that avoid the United States, the CC value only drops from 0.74 to 0.55.

With national policies on the rise, we believe that researchers, ISPs, and policy makers will soon need to understand the impact that these policies can have on other countries, networks, and even individual IP prefixes. Our major contribution is the development of a framework for studying interdomain routing at the nation-state level. This includes identifying and a dressing the many challenges of inferring the country level paths, developing network centrality metrics appropriate for the problem, validating the methods, and reporting initial results.

The paper is organized as follows. In the next section we briefly discuss the Internet’s topology and the correct granularity for measuring country paths. In Section 3 we design, implement, and validate the Count Path Algorithm (CPA) for inferring country-paths from a pair of source and destination IP addresses. The algorithm has several stages, as it must first infer the interdomain path, and then intradomain paths, and finally determine the country path. Next, Section 4 reviews betweenness centrality and presents two extensions for measuring a country’s influence over global reachability. These metrics take as input the global measurement produced by the CPA. In Section 5, we apply our inference techniques to sample data sets of traceroutes and AS paths, as well as inferred paths between all know IP prefixes. This helps validate that our metrics are robust to inference error. We also present initial results characterizing the data produced by the CPA. Next we discuss future work and other possible challenges at country level analysis in Section 6, we review related work in Section 7, and finally conclude in Section 8.

Stay tuned.

[The pic in the upper right is from Muzzle Watch.]

(Cheers, Simon)

Nxx Zxxxxxx -  Big Music: Jump! New Zealand ISP: How high?, March 19, 2009
Fxxxxx – Still a chance to defeat French 3 strikes law, March 17, 2009
determined to join CXXXX – Aussie government: you`ve been warned, March 21, 2009
RIPE NCC – YouTube Hijacking: A RIPE NCC RIS case study, February, 2008

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