Explainer

Government Internet Censorship: How Countries Block Websites

More than half the world's internet users live under some form of government-imposed internet restriction. From China's comprehensive Great Firewall to Turkey's periodic social media bans, state-level censorship uses a range of technical and legal mechanisms. Here's how it works.

Technical methods governments use

DNS blocking — National DNS resolvers return no result or a forged address for banned domains. Easy and cheap but trivially bypassed by changing DNS.

IP blocking — Border routers block traffic to specific IP addresses. CDN-hosted sites (Cloudflare, AWS) make this costly because blocking one IP harms thousands of legitimate sites.

Deep Packet Inspection (DPI) — Hardware at internet exchange points inspects packet headers and TLS SNI fields to identify and drop traffic to banned sites over HTTPS. Used heavily in China, Russia, and Iran.

BGP hijacking / route withdrawal — State-level manipulation of internet routing tables to make IP ranges disappear entirely from the national internet.

Keyword filtering — URLs or page content containing banned keywords (political figures' names, sensitive events) are blocked in real time. Used in China.

Bandwidth throttling — Instead of outright blocking, a service is made so slow it becomes unusable. Used against Twitter/X in several countries.

China: The Great Firewall

China operates the most sophisticated national internet censorship system in the world, known colloquially as the Great Firewall (GFW). The system is managed by the Cyberspace Administration of China and enforced by all licensed ISPs and backbone providers.

Blocked: Google (all services), Facebook, Instagram, YouTube, Twitter/X, WhatsApp, Telegram, Wikipedia (English), New York Times, BBC
Methods: DPI with active probing, DNS poisoning, IP blocking, keyword filtering
VPN detection: The GFW actively probes suspected VPN connections and blocks protocols it identifies
Legal: Using unauthorized VPNs is illegal for individuals, though enforcement is inconsistent

Russia: Roskomnadzor (RKN)

Russia maintains a national blocklist managed by Roskomnadzor (RKN), the federal media regulator. ISPs are legally required to implement blocks via the TSPU (Technical Means of Countering Threats) — DPI hardware installed at internet exchange points.

Since Feb 2022: Facebook, Instagram (Meta), BBC Russian, Deutsche Welle
Blocked periodically: Twitter/X (restored after compliance pressure), LinkedIn (since 2016)
RKN blocklist contains millions of URLs, many added without court order
The 2018 Telegram block accidentally blocked millions of AWS/Google IPs before being lifted

Other countries

Iran — Blocks Instagram, WhatsApp, YouTube, Twitter, Facebook, many news sites. Nationwide internet shutdowns during protests.

Turkey — Wikipedia was blocked 2017–2020. Periodic bans on Twitter, YouTube, Discord during crises. Mandatory ISP filtering.

Pakistan — YouTube blocked 2012–2016. TikTok blocked/unblocked multiple times. CSAM and blasphemy content routinely blocked.

North Korea — Citizens have no access to the global internet. A national intranet (Kwangmyong) exists with approved content only.

India — Blocks pornography sites (Supreme Court order), certain VPN apps, and has enacted temporary regional shutdowns.

EU/UK — Mandatory ISP-level blocks on piracy sites, CSAM, and (in the UK) extreme content under the Online Safety Act.

How to access censored websites

VPN — Encrypts and tunnels all traffic to a server outside the country. The most reliable method, though governments increasingly try to block VPN protocols. Use obfuscated VPN protocols (Shadowsocks, obfs4, Stealth mode in NordVPN) in heavily censored environments.

Tor Browser — Routes traffic through three encrypted relays. Built-in bridges (meek, snowflake) help bypass Tor blocking in China and Iran. Slow but very reliable for text content.

Psiphon / Lantern — Free tools specifically designed for censorship circumvention, using a mix of VPN, SSH, and HTTP proxy technologies.