How do they block some content in some countries, like India is doing with Pakistan, what is the tech stack and tech behind it

Blocking or censoring online content in certain countries, such as India blocking Pakistani websites and online channels, involves a combination of legal, technical, and infrastructural measures.

Why Do Countries Block Content?

Countries block online content for various reasons, often linked to national security, political considerations, cultural norms, or legal requirements. For example, India has blocked Pakistani websites, YouTube channels, and IP addresses as part of diplomatic measures and to counter propaganda or content deemed harmful to public order or national security. Other reasons for blocking content include preventing access to copyright-infringing material, stopping the spread of extremist content, or controlling misinformation.

Legal and Administrative Framework

Before any technical blocking happens, governments typically issue legal orders or directives to internet service providers (ISPs) or platforms. In India, the government can invoke laws such as the Indian Telegraph Act or rules under the Information Technology Act to order ISPs to block access to specific websites or online content. These orders are often justified by citing threats to national security, public safety, or to prevent unrest.

India has suspended visa services for Pakistani nationals, closed airspace to Pakistani aircraft, and blocked Pakistani YouTube channels and websites following terrorist attacks or diplomatic tensions. These actions are part of a broader strategy to restrict communication and influence from Pakistan within India’s digital space.

The Technical Methods Behind Content Blocking

Once the legal framework is in place, the actual blocking of content is enforced using several technical methods. These methods are implemented mainly by ISPs, who control the internet gateways through which users access online content.

1. DNS Filtering and Redirection

When you type a website address (like www.example.com), your device asks a Domain Name System (DNS) server to translate that name into an IP address, which is the actual location of the website on the internet.

• How it works: ISPs maintain DNS servers that resolve these names. If a website is banned, the ISP’s DNS server will refuse to translate the domain name or redirect it to an incorrect or blank address. This makes the website unreachable to users relying on that DNS.

• Limitations: Users can bypass this by using alternative DNS services, such as Google DNS or Cloudflare DNS, unless those are also blocked or filtered.

2. IP Address Blocking

Websites are hosted on servers identified by IP addresses. ISPs can block access to specific IP addresses associated with banned websites.

• How it works: ISPs maintain blacklists of IP addresses to block. When a user tries to access a blocked IP, the ISP drops the connection, preventing access.

• Collateral damage: Since many websites can share the same IP address (shared hosting), blocking one IP can unintentionally block multiple websites.

3. URL and Keyword Filtering

More advanced censorship involves inspecting the actual web traffic for specific URLs or keywords.

• How it works: Using technologies like Deep Packet Inspection (DPI), ISPs or government agencies analyze data packets traveling over the network to detect requests for banned URLs or content containing forbidden keywords.

• Effectiveness: This method can block access to specific pages within a website or filter content dynamically.

4. Blocking at the Platform Level

Governments can also order platforms like YouTube, Google, or social media companies to block or remove certain channels, videos, or accounts within their services for users in the country.

• For example, India blocked Pakistani Prime Minister Shehbaz Sharif’s YouTube channel and other Pakistani political and media accounts citing national security concerns.

• Platforms comply by geoblocking content, making it unavailable to users in the specified country while remaining accessible elsewhere.

5. Network Throttling and Connection Resets

In some cases, ISPs may slow down traffic to certain sites or reset connections to disrupt access without outright blocking.

The Tech Stack Behind Content Blocking

The infrastructure and tools used for censorship involve a combination of hardware and software components:

• Internet Service Providers (ISPs): They are the primary enforcers of blocks, as they control the network gateways that connect users to the internet.

• Firewalls and Filtering Appliances: Specialized hardware or software devices capable of DPI, packet filtering, and traffic shaping. These can inspect, block, or reroute traffic based on rules set by authorities.

• DNS Servers: Managed by ISPs or government agencies, these servers enforce DNS filtering by refusing to resolve banned domains.

• Blacklists and Whitelists: Databases of banned or allowed IP addresses, URLs, and keywords maintained centrally and distributed to ISPs for enforcement.

• Legal and Monitoring Systems: Backend systems that process government orders, track compliance, and monitor network traffic for violations.

How India Implements Content Blocking

India uses a combination of the above methods to block content:

• DNS Filtering: ISPs block domain name resolutions for banned Pakistani websites.

• IP Blocking: India contemplates blocking all Pakistani IP addresses, effectively cutting off access to Pakistani-hosted websites.

• Platform-Level Blocking: India has ordered platforms like YouTube to block Pakistani channels, including news outlets and political figures.

• Legal Orders: The government issues blocking orders citing national security or public order under Indian laws.

• Collaboration with ISPs and Content Providers: India works with major ISPs like Tata Communications and Airtel to manage internet gateways and enforce blocks.

• Surveillance and Monitoring: Discussions around projects similar to China’s Golden Shield Project indicate interest in mass surveillance and more comprehensive internet control.

Challenges and Circumvention

Despite these measures, users often find ways to bypass censorship:

• Using VPNs (Virtual Private Networks): VPNs encrypt traffic and route it through servers outside the country, making it difficult for ISPs to block specific content.

• Alternative DNS Services: Users switch to DNS servers that do not enforce local censorship.

• Proxy Servers and Tor Network: These tools anonymize and reroute traffic to circumvent blocks.

Governments respond by blocking VPN protocols, throttling connections, or requiring real-name registration to discourage circumvention.

Global Context and Emerging Technologies

India’s approach is part of a global trend where countries use a mix of technical and legal tools to control online content. China’s Great Firewall is the most sophisticated example, combining DNS tampering, IP blocking, keyword filtering, and DPI to create a heavily filtered internet environment.

Emerging technologies like AI-based content filtering and blockchain-based decentralized hosting are shaping the future of censorship and resistance. Governments may use machine learning to detect subversive content, while activists use decentralized networks to evade blocks.

Blocking online content in countries like India involves a layered approach combining legal orders, ISP cooperation, and technical methods such as DNS filtering, IP blocking, and platform-level restrictions. The technology stack includes network infrastructure, firewalls, DNS servers, and monitoring tools. While effective to a degree, these measures face challenges from users employing circumvention tools. The ongoing interplay between censorship technologies and resistance shapes the evolving landscape of internet freedom and control.