A Technical Look at Iran's Internet Shutdowns

Summary

A Technical Look at Iran’s Internet Shutdowns At 13 Jul 2025 By Zola Gonano Every time mass protests erupt in Iran, a familiar pattern follows: the flow of information stops. The internet slows to a crawl or disappears entirely. But how does a modern country survive cutting itself off from the internet? Wouldn’t that break everything? Not quite, because the Islamic Republic has spent the last decade building an internet within the internet. The National Information Network (NIN): Isolation by Design Iran’s National Information Network (NIN) is a state-controlled intranet designed to keep domestic services running even when international connectivity is cut off. Think of it as a national sandbox: websites, banking portals, messaging apps, and e-government services that function entirely within Iran’s borders. This setup serves two primary functions: It enables selective blackouts: the state can block international platforms (like WhatsApp, Instagram, or news sites) while keeping local services (like state media, banking apps) fully operational. It forces ISPs to route traffic through government-controlled gateways, making it easier to monitor, filter, or shut down parts of the network on demand. Layered on top of this is the IRGFW—the Iranian Great Firewall. Modeled after China’s Great Firewall (GFW), but with stricter enforcement and more centralized control, it filters, blocks, and surveils traffic across the country. On paper, it seems solid and impenetrable. But there’s always a hole. Always. What Can Be Done in This Situation? The Iranian internet blockade is aggressive but it’s not perfect. Like any large-scale filtering system, it relies on outdated metadata, and static blocklists. And that’s where cracks begin to form. The Known Flaw: IPs Are Rented, Not Owned IPv4 addresses are limited and constantly reallocated. Most are rented and passed between hosting providers, resold between datacenters, or migrated across regions. The Iranian filtering system uses Geo...