IP Blocks and Censorship: Internet Restrictions

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In the era of a global internet, blocking IP addresses has become one of the most common methods of controlling access to information. Censorship through IP blocks is used to restrict access to websites, platforms, and applications, as well as to manage the flow of information. However, IP blocking often creates additional challenges, including accidental restrictions on legitimate resources.

How Do Governments Block Entire IP Blocks?

Blocking IP addresses is implemented by filtering traffic at the level of internet service providers (ISPs). Governments or regulatory bodies use these methods to restrict access to specific sites or services:

1. Blacklisting IP Addresses

What is it?
Certain IP addresses or entire blocks are added to a blacklist, and all traffic to these addresses is blocked. This is a simple but not always accurate way of controlling access.

Example:
China’s “Great Firewall” extensively uses blacklists to filter content.

2. Blocking by CIDR Blocks

What is it?
Instead of blocking a single IP address, entire ranges, such as /24 (256 addresses) or even larger blocks, are filtered.

The problem:
If a single IP block contains both restricted and legitimate resources, they all become inaccessible.

3. Deep Packet Inspection (DPI)

What is it?
A more advanced method that analyzes traffic packets to identify and block specific addresses.

Example:
Russia uses DPI extensively to block certain applications, such as Telegram.

4. Geo-blocking of IPs

How does it work?
IP addresses belonging to specific regions are blocked to restrict access to content from certain countries.

Example:
Streaming services may block users from countries where they lack broadcasting licenses.

Ways to Bypass IP Blocking Using VPNs and Proxy Servers

When IP addresses are blocked, users often seek ways to bypass the restrictions. The most common methods include:

1. VPN (Virtual Private Network)

A VPN allows users to hide their real IP address by replacing it with the address of a server located in another country.

How does it work?
User traffic is encrypted and routed through a VPN server, masking the original IP.

Advantages:

  • Bypasses geographic and local restrictions.
  • Protects data from interception.

Drawbacks:

  • Some VPN services are also blocked by governments (e.g., in China).

2. Proxy Servers

Proxy servers redirect user requests through their own IP address, helping to bypass blocks.

Advantages:

  • Simple to use.
  • Lower latency compared to VPNs.

Drawbacks:

  • Lack of encryption makes traffic vulnerable.
  • Proxy servers themselves are often blocked.

3. DNS Override

Changing DNS settings allows users to redirect requests to unblocked servers.

Example:
Using Google DNS (8.8.8.8) or Cloudflare DNS (1.1.1.1) to bypass restrictions.

4. DPI Bypass Technologies

Example:
Protocols like Shadowsocks or obfuscated OpenVPN help disguise VPN traffic from DPI systems.

How Companies Protect Their Services from Accidental IP Blocking

When governments block IP blocks, it often results in legitimate resources being restricted alongside prohibited sites. Companies implement various measures to minimize these risks:

1. Using Distributed Networks (CDN)

What is it?
Content is distributed across a network of servers worldwide (e.g., Cloudflare, Akamai).

Advantages:

  • If one server or IP is blocked, traffic can be rerouted through another.
  • Hides the real IP address of the resource.

2. Frequent IP Address Rotation

How does it help?
Regularly rotating IP addresses makes it harder for them to be blocked. Many major companies, such as Google and Amazon, actively use this tactic.

3. Utilizing IPv6

Why does it work?
Migrating to IPv6 complicates mass blocking because the number of available addresses is significantly larger than IPv4.

Example:
Some companies provide content exclusively over IPv6 to reduce the risk of blocking.

4. Collaborating with Regulators

How does it work?
Legitimate companies can appeal to regulators to remove their IP addresses from blacklists.

Example:
Cases have been documented in Russia where large companies successfully had their IPs unblocked through legal and administrative actions.

5. Anti-blocking Technologies

Example:
Technologies like Anycast allow a single IP address to be used on multiple servers, making it harder to block specific targets.

Conclusion

IP blocking is a powerful but often inefficient tool for internet censorship. Governments use various methods, from simple blacklists to complex traffic analysis. However, technologies like VPNs, proxies, and distributed networks enable users to bypass restrictions.

For companies, protecting their services from accidental blocking is a critical challenge, especially in countries with strict censorship. Using CDNs, rotating IP addresses, and transitioning to IPv6 can minimize risks and ensure accessibility for users worldwide.