Internet Censorship Explained - Computerphile

Summary

This script delves into internet censorship, detailing the mechanisms of control over user-publisher communication. It explains how censors can halt information flow through DNS redirection, IP blocking, and application layer blocking. The discussion highlights the 'arms race' between censorship and resistance, with technology evolving to counteract control. It also touches on the importance of anonymity and privacy in resisting censorship, suggesting tools like TOR to maintain user privacy.

Takeaways

• 🌐 Internet censorship involves controlling the dissemination of information by targeting the user, publisher, or the information itself.
• 🔍 The censorship process can be broken down into blocking publication, discouraging access, or coercing users to avoid certain content.
• 💻 An example of censorship is blocking access to a website like 'youtube.com' by manipulating DNS queries or IP addresses.
• 🔄 DNS redirection or sinkholing is a method where a censor-controlled server provides a false IP address for a domain, leading users away from the intended site.
• 🚫 IP blocking is a direct method where a censor prevents a user's connection to a specific IP address, effectively stopping access to a site.
• 🔍 Application layer blocking allows censors to inspect content for keywords and disrupt connections carrying censored information.
• 👤 The human element of censorship resistance involves ensuring privacy and anonymity for both publishers and users of information.
• 🔑 Censorship resistance systems aim to provide privacy, but users often need to combine these with additional anonymity services like TOR for better protection.
• 📰 Traditional censorship, like blocking content in newspapers, contrasts with digital censorship which involves more sophisticated technical methods.
• 🏃‍♂️ The battle between censorship and resistance is an ongoing 'arms race', with technology for controlling and accessing information constantly evolving.
• 🐱‍👤 The 'cat and mouse game' between censors and those resisting censorship involves continuous adaptation as each side develops new strategies and technologies.

Q & A

What are the main components of communication as it relates to internet censorship?

The main components of communication in the context of internet censorship are the user, the publisher, and the information being disseminated. The user is the individual seeking information, the publisher is the source providing the information, and the information itself is the content being shared between them.

How does internet censorship aim to control the flow of information?

Internet censorship aims to control the flow of information by either preventing the publication of certain content by publishers, discouraging users from accessing that information, or directly coercing users to not access it. The ultimate goal is to stop the dissemination of information deemed undesirable by the censor.

Can you explain the example given in the script about how censorship might occur if 'youtube.com' is blocked?

If 'youtube.com' is blocked, a user attempting to access it would normally type the URL into their browser, which would then query a DNS server for the corresponding IP address. A censor could interfere at this point by either claiming the domain does not exist or by providing a false IP address, leading to DNS Redirection or DNS Sinkholing.

What is DNS Redirection or DNS Sinkholing in the context of internet censorship?

DNS Redirection or DNS Sinkholing is a censorship technique where a censor-controlled DNS server provides a false IP address for a domain, redirecting the user to a different, often controlled, site instead of the originally requested one.

What is IP Blocking and how does it relate to internet censorship?

IP Blocking is a method of internet censorship where the censor prevents users from connecting to a specific IP address, effectively blocking access to a website or service. This is done at the IP layer, independent of the domain name system.

What is application layer blocking, and how does it differ from DNS or IP blocking?

Application layer blocking is a sophisticated form of censorship that involves inspecting the content of data packets for specific keywords or patterns that indicate undesirable information. Unlike DNS or IP blocking, which operate at lower levels of the network stack, application layer blocking can target specific content within the communication stream.

How can censorship resistance systems help protect user privacy and anonymity?

Censorship resistance systems can protect user privacy and anonymity by making it difficult for censors to trace the identity of users accessing certain information. By combining these systems with anonymity services like TOR, users can maintain a higher level of privacy and reduce the risk of coercion or identification.

What is the 'cat and mouse game' mentioned in the script in relation to censorship and censorship resistance?

The 'cat and mouse game' refers to the ongoing struggle between censors who attempt to control and restrict information and those who develop and use censorship resistance technologies. As censorship methods evolve, so do the countermeasures, creating a continuous cycle of adaptation and response.

Why is it challenging for censors to control information on social media platforms like Twitter and Facebook?

Controlling information on social media platforms is challenging for censors because of the vast amount of user-generated content and the fact that these platforms are hosted by major companies like Google and Twitter. Blocking these platforms entirely would result in significant collateral damage and affect many innocent users.

What does the term 'arms race' imply in the context of censorship and censorship resistance?

The term 'arms race' in this context implies the continuous competition between the development of censorship techniques and the creation of new censorship resistance technologies. As one side advances, the other must innovate to counteract the new measures, creating a cycle of escalating technological advancements.

How can users protect themselves from coercion by censors when accessing the internet?

Users can protect themselves from coercion by using a combination of censorship resistance systems and anonymity services. This includes using VPNs, proxy servers, and privacy-focused browsers, as well as being aware of the legal implications and risks associated with accessing censored content.

Outlines

00:00

🌐 Internet Censorship and Its Mechanisms

The paragraph introduces the concept of internet censorship by breaking down communication into three components: the user, the publisher, and the information being shared. It explains that censorship involves measures to prevent the dissemination of information, either by blocking publication, discouraging access, or coercing users. An example is provided where 'youtube.com' is blocked, and the process of how a user's browser interacts with DNS servers to resolve domain names is detailed. The paragraph further explains how censorship can occur at different levels: DNS redirection or sinkholing, IP blocking, and application layer blocking where content is scrutinized for keywords that trigger censorship. The discussion also touches on the human element of censorship resistance, emphasizing the importance of privacy and anonymity for users and publishers to avoid being traced.

05:03

🔄 The Censorship Resistance Arms Race

This paragraph delves into the dynamic struggle between censorship and censorship resistance, likening it to an 'arms race'. It points out the challenges faced by censors in controlling information on social media platforms like Twitter and Facebook, which host vast amounts of user-generated content. The paragraph highlights the difficulty for censors to block entire platforms without causing significant collateral damage due to the widespread use and reliance on these services. It also suggests that as censors enhance their methods, censorship resistance systems must evolve to counter these measures, creating a continuous cycle of adaptation and response. The paragraph concludes by hinting at the ongoing development of new strategies and technologies in this ongoing battle between censorship and resistance.

Keywords

💡Internet censorship

Internet censorship refers to the control or suppression of what can be accessed, published, or viewed on the internet by governments or other entities. In the video, it is discussed as a series of steps that censors may take to prevent the dissemination of information, such as blocking websites or discouraging access to certain content. The example of 'youtube.com' being blocked illustrates how censorship can occur at various levels of internet communication.

💡User

A user, in the context of the video, is an individual who seeks to access information or services online. The video explains that the 'who' in communication is the user, who interacts with the publisher to access information. The censorship mechanisms can directly target users, coercing them to not access certain information.

💡Publisher

A publisher, as mentioned in the script, is the entity that provides information to the user. In the context of internet censorship, publishers can be affected when censors attempt to stop the publication of certain information. The video uses 'abc.com' as an example of a publisher whose domain might be targeted by censorship efforts.

💡DNS server

A DNS (Domain Name System) server is responsible for translating domain names into IP addresses that computers use to identify each other on the network. The video explains how a censor can interfere with this process by either claiming a domain does not exist or by redirecting the DNS query to a different IP address, a technique known as DNS Redirection or DNS Sinkholing.

💡IP Blocking

IP Blocking is a censorship technique where access to specific IP addresses is denied. The video describes this as a method where a censor can prevent a user from connecting to a certain IP address, such as '1.2.3.4', which is associated with the publisher's website.

💡Application layer blocking

Application layer blocking is a sophisticated form of censorship that involves inspecting the content of data packets for specific keywords or patterns that indicate undesirable information. If such content is detected, the censor can disrupt the communication by sending TCP reset packets or dropping the packets, as mentioned in the video.

💡Anonymity

Anonymity, as discussed in the video, is the state of being unidentifiable within a set of users. It is crucial in censorship resistance as it helps ensure that users cannot be traced or coerced. The video suggests that anonymity services like TOR can be combined with censorship resistance systems to enhance user privacy.

💡Coercion

Coercion, in the context of the video, refers to the act of forcing users or publishers to comply with censorship demands. It can involve direct pressure or threats, and the video suggests that comprehensive censorship resistance systems should aim to protect users from such coercion.

💡Censorship resistance

Censorship resistance encompasses the strategies and tools used to counteract internet censorship. The video describes it as an ongoing 'arms race' between the technology used for information control and the technology used to circumvent these controls. Examples include the development of new platforms and the use of anonymity services.

💡Social media

Social media platforms like Twitter and Facebook are mentioned in the video as examples of modern challenges for censorship. These platforms host a vast amount of user-generated content, making it difficult for censors to control the flow of information without causing significant disruption to other services.

💡Cat and mouse game

The 'cat and mouse game' is a metaphor used in the video to describe the dynamic between censors and those who resist censorship. It implies a continuous cycle of one side implementing new controls and the other side developing new ways to bypass these controls, reflecting the evolving nature of the struggle over internet freedom.

Highlights

The main components of communication are the user, the publisher, and the information.

Internet censorship involves stopping the publication or access to information.

Censors may coerce users directly to prevent access to certain information.

A simple example of censorship is the blocking of youtube.com.

DNS queries are a point where censors can intervene in internet access.

Censors can control DNS servers to redirect or block domain name resolutions.

IP Blocking is another method censors use to prevent access to specific websites.

Application layer blocking allows censors to inspect content for keywords and disrupt connections.

Censorship resistance involves publishers and users maintaining privacy and anonymity.

Anonymity services like TOR can be combined with censorship resistance systems.

Censorship in traditional media, such as newspapers, has evolved with technology.

Censorship resistance software is part of an ongoing 'arms race' with censorship techniques.

Social media platforms complicate censorship due to the volume of user-generated content.

Blocking major platforms like Twitter or Google would cause significant collateral damage.

Censorship resistance systems must adapt as censors employ more sophisticated techniques.

The battle between censorship and resistance is likened to a cat and mouse game.

Transcripts

Well, we are going to talk about internet censorship.

So the main components of a communication are usually

Who is talking to whom, and what are they talking about?

So usually the who portion is called the user,

The Whom portion is called the publisher,

Which provides some information to the user.

and, the what part,

Is the information Itself.

So... internet censorship,

Comprises of...

A range of steps that the censor might take

to either stop the publication of information, on the publisher's side.

Or discourage the access to that information or the link that connects the user to the publisher.

Or directly coerce users to not access that information.

But the key point is to stop the information from being disseminated.

I'll give you a very simple example of how censorship takes place,

Which would kind of gives us also an Idea

Of what are the different mechanisms available.

If youtube.com has been blocked,

and I am a user

Usually the set of steps that would take place is that I would type "youtube.com" into my browser,

Then behind the scenes my browser would generate a query to a DNS server.

okay it was "youtube.com" but now it's "abc.com"

so it will generate a DNS Query to the local DNS Server asking

"what is the IP address to which I should map abc.com?"

now, either the DNS server would already know the IP address corresponding to abc.com

Or it would ask other DNS servers, recursively, on the internet,

and somehow find the IP address corresponding to abc.com

Once it has that IP address it will return that IP Address

to the user

Then the user's browser will use that IP adress

to connect to abc.com

which is at 1.2.3.4

and send an HTTP Get Request

for some index page.

and if it all works well,

then abc.com will respond with the corresponding webpage

now as you can see this involves interaction between different entities.

What a censor can do,

is that it can block the user's connection at this point

so when the user asks for the IP adress corresponding to abc.com

the censor controlled DNS server could either say that this domain does not exist.

or it can say that oh,

the IP address corresponding to this domain name is 4.4.4.4

which is something which is under the control of the censor

this is called DNS Redirection or DNS Sinkholing

then, at the IP layer,

Say, if it doesn't block the connection at this layer,

then in the next step

what a censor can potentially do is that it can block,

user's attempt to connect to 1.2.3.4

which is called IP Blocking

and then there's this concept of application layer blocking

which dosen't involve the domain name, or the IP Address

but rather a sophisticated censor might be able to look at the content,

that is traveling over this channel between the user, and abc.com

and if it finds some offensive keywords

which are indicative that this connection is

carrying some information which should be censored

then based on that keyword

it will send TCP.. it can potentially send TCP

reset packets to both sides

or do something else to just,

drop packets to just disrupt the communication

[offscreen] Break the Connection, OKay

do people get into trouble when they try in to get in these sites? What's it?

is that something that can be traced, when if...

yes

yeah. So...

when we talk about the human element of censorship resistance

this involves publishers of information and also the users of information

and...

that basically goes into the area of privacy.

and anonymity

so basically anonymity ensures

that the users of a censorship resistance system

may not be traceable.

and...

what you just mentioned is called coercion of users or coercion of publishers

and ideally one of the goals of a comprehensive censorship resistance systems

is to afford that kind of privacy to users

but usually they don't do that and that's usually something

that users have to take care of themselves by

by combining their use of censorship resistance systems with anonymity services like TOR

[Off screen] I know that a long time ago people would block out things

in newspapers or blockout things in images and that would be a form of censorship.

So how does it work then when people are censoring in these levels we've just talked about

and yet there's censorship resistance software out there, what's going on, what will be the next "thing"?

I think it's like an arms race, right? because the technology

that is used to disseminate and retrieve information is constantly evolving

so now we have social media websites like Twitter,

Facebook, which have loads and loads of users generated content

so on the one end it's very difficult for a censor

to retain that control of information

because now there is this whole bulk of information

to go through

and then also because this content is hosted by sites like

Google or Twitter

so they can't just block the IP address of Twitter

and block the IP address of Google

because that would incur alot of collateral damage

the false positives that we previously talked about.

but when the censor ups their game

then the censorship resistance systems also take the next step up

so there's basically a cat and mouse game which is in play here.