{"id":38090,"date":"2019-10-31T22:21:36","date_gmt":"2019-10-31T19:21:36","guid":{"rendered":"https:\/\/prohoster.info\/blog\/eksperiment-cachebrowser-obhod-kitajskogo-faervola-bez-proksi-s-pomoshhyu-keshirovaniya-kontenta\/"},"modified":"2019-10-31T22:21:36","modified_gmt":"2019-10-31T19:21:36","slug":"eksperiment-cachebrowser-obhod-kitajskogo-faervola-bez-proksi-s-pomoshhyu-keshirovaniya-kontenta","status":"publish","type":"post","link":"https:\/\/prohoster.info\/en\/blog\/administrirovanie\/eksperiment-cachebrowser-obhod-kitajskogo-faervola-bez-proksi-s-pomoshhyu-keshirovaniya-kontenta","title":{"rendered":"CacheBrowser Experiment: Bypassing the Chinese Firewall without a proxy using content caching","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

\"CacheBrowser<\/a><\/noindex><\/p>\n

Image: Unsplash<\/a><\/noindex><\/i><\/p>\n

Today, a significant portion of all content on the internet is distributed using CDN networks. However, there has been little research on how different censors exert their influence on such networks. Scholars from the University of Massachusetts analyzed<\/a><\/noindex> explore possible methods for blocking CDN content, using the practices of the Chinese authorities as an example, and have also developed a tool to circumvent such blocks.<\/p>\n

We have prepared an overview of the main findings and results of this experiment.<\/a><\/noindex><\/p>\n

Introduction<\/h2>\n

\nCensorship is a global threat to freedom of speech on the internet and free access to information. Much of this is possible because the internet borrowed the 'end-to-end communication' model from telephone networks of the 1970s. This allows blocking access to content or communication between users with minimal effort or cost, simply based on an IP address. Here are several methods ranging from blocking the address of the prohibited content to preventing users from even learning about it through DNS manipulation.<\/p>\n

However, the development of the internet has also led to new ways of distributing information. One of these is the use of cached content to improve performance and speed up communications. Today, CDN providers handle a significant volume of total traffic worldwide \u2014 the leading player in this segment, Akamai, accounts for up to 30% of global static web traffic. <\/p>\n

A CDN network is a distributed system for delivering internet content at maximum speed. A typical CDN network consists of servers located in various geographical locations that cache content to deliver it to those users closest to that server. This significantly increases the speed of online communication.<\/p>\n

In addition to improving the quality of service for end-users, CDN hosting helps content creators scale their projects while reducing the load on infrastructure.<\/p>\n

Censoring CDN content<\/h2>\n

\nDespite the fact that CDN traffic already constitutes a significant share of all information transmitted over the internet, there is still very little research on how real-world censors approach its control. <\/p>\n

The authors of the study began by investigating censorship techniques that could be applied to CDNs. They then examined the actual mechanisms used by the Chinese authorities. <\/p>\n

First, let's discuss the possible methods of censorship and their applicability for controlling CDNs.<\/p>\n

IP filtering<\/h2>\n

\nThis is the simplest and least expensive internet censorship technique. By using this approach, the censor identifies and blacklists the IP addresses of resources hosting prohibited content. Controlled internet providers then stop delivering packets sent to such addresses. <\/p>\n

IP blocking is one of the most common methods of internet censorship. Most commercial network devices are equipped with functions to implement such blocks with minimal computational costs.<\/p>\n

However, this method is not very suitable for blocking CDN traffic due to certain properties of the technology itself:<\/p>\n