Iran offline: How a government can turn off the internet

There’s an ongoing, near-total blackout of the internet in Iran. The shutdown is part of a response by the government to ongoing protests against rising inflation and the value of the nation’s currency plummeting. Since protests began more than two weeks ago, only an estimated 3% of Iranians have stayed online through the satellite internet system Starlink. Doing so is a crime. So, today on the show: Iran offline. We get into how the internet works, how a government can shut it down and how scientists are monitoring the nation’s connectivity from afar. Check out more of NPR's coverage of Iran: - Iran Protests Explained https://www.npr.org/2026/01/22/nx-s1-5684033/iran-2026-protests - There's an internet blackout in Iran. How are videos and images getting out? https://www.npr.org/2026/01/15/nx-s1-5678567/iran-internet-blackout-starlink - Iran blocked the internet amid deadly protests. Some voices are still getting through https://www.npr.org/2026/01/22/nx-s1-5680784/iran-blocked-the-internet-amid-deadly-protests-some-voices-are-still-getting-through Interested in more science behind the headlines? Email us your question at [email protected] mailto:[email protected] – we may tackle it in a future episode! Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave http://plus.npr.org/shortwave. This episode was produced by Berly McCoy, edited by Rebecca Ramirez and fact checked by Tyler Jones. Robert Rodriguez was the audio engineer. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:00Speaker 00

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• 0:18Emily Kwong?

  You're listening to Short Wave from NPR. Amanda Meng was on vacation the day before New Year's Eve when the messages began.

• 0:28Speaker 02

  I got a signal message. There had been some on the ground reports of network interference. And of course, they wanted to know what we could see in our measurements.

• 0:37Emily Kwong?

  Amanda is a part of a research project called IOTA, or Internet Outage Detection Analysis. Her research partners were telling her that something weird might be happening with the internet in Iran.

• 0:48Speaker 02

  And it actually took several days before we could see something abnormal in the data. And then on January 8th, we all started to see our measurements just kind of start to fall off. So, a near a complete shutdown where Iranians were no longer connected to the global internet.

• 1:09Emily Kwong?

  This is not the first time the Iranian regime has shut down the internet.

• 1:13Speaker 02

  The regime during times of mobilization will shut down the internet to try and suppress that mobilization as well as to control information. Also, creating that chaos of not being able to connect with people, connect to emergency services,

• 1:32Speaker 02

  might drive people back home, out of the streets.

• 1:35Emily Kwong?

  And of course, the government has said it's shutting down the internet for national security.

• 1:39Speaker 02

  Mm hmm. Yes, right. They always offer some sort of reason or motivation, and it often has to do with national security.

• 1:47Emily Kwong?

  The current internet shutdown came as a response to protests across Iran, with crowds calling for political change amid rising inflation and a devastating drop in the value of Iranian currency, the real. Since protests began, more than 5,000 people have been killed, according to the US-based human rights activist news agency. NPR has independently verified that number, and observers and activists estimate the death toll may be much higher. Now, when it comes to the internet, initially, it was a total digital blackout. But over time, some selective services have come back online. These are known as whitelisted services.

• 2:24Speaker 02

  And so we are starting to see Google Search, Google Images, which are whitelisted, applications be accessible, but still only within the domestic internet.

• 2:34Emily Kwong?

  So emails cannot be sent outside of Iran, for instance.

• 2:38Speaker 02

  Yeah, we're not seeing Gmail up at all.

• 2:41Emily Kwong?

  Despite the near-total internet shutdown, some voices are getting through, like this protester, who sent a voice memo to NPR's Arzu Razvani.

• 2:54Speaker 03

  I can say now the city is in a trance-like state. People don't leave their houses much. It feels as if, as the expression goes, they splashed death everywhere.

• 3:05Emily Kwong?

  This man is among the 3% of Iranians who have managed to stay online through the satellite internet system Starlink. But doing so is a crime. Today on the show, Iran offline: how computer networking happens, how a government can shut it down, and how scientists are monitoring that connectivity from afar. I'm Emily Kwong, and you're listening to Short Wave, the science podcast from NPR.

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• 5:03Emily Kwong?

  OK, so to talk more about the Internet and the Internet shutdown in Iran, I'm going to dig deeper with Amanda Meng, a social scientist at Georgia Tech, who you heard from earlier, and Alberto Dainotti, a computer scientist also at Georgia Tech, who studies Internet infrastructure. And Alberto, let's start from a technical standpoint. What is the Internet?

• 5:24Speaker 05

  So Internet stands for internetwork. So it's a network of networks. So it was designed to make completely different networks interoperable and interconnect them. Some of these are the networks of our ISPs, internet providers, that allow us to connect to the Internet. Some are networks of big telecom operators. Some are networks of universities, like ours, for example.

• 5:50Emily Kwong?

  I know this is extremely complicated, but what exactly is a network?

• 5:54Speaker 05

  OK, so we say that a network is a set of endpoints, like hosts and clients and servers that want to talk to each other.

• 6:04Emily Kwong?

  Right, like a computer sends an email to another computer. Those are endpoints.

• 6:08Speaker 05

  Yes, a cellphone, a laptop.

• 6:12Speaker 05

  And so on. And these endpoints, somehow they are connected to intermediate nodes, which we call routers and switches.

• 6:20Emily Kwong?

  Ah, yes.

• 6:21Speaker 05

  Right. But you've got to even think about cell towers, for example. You see a traffic from many endpoints and then they route it around. But the way endpoints and routers are connected with each other is really through links, which can mean actual cables, like fiber cables, or the cable that reaches our home, or internet cables. But it can be even Wi-Fi, links that are in the air, basically, like radio signals, cellphone signals, satellite signal. Those are links that interconnect these nodes.

• 6:52Emily Kwong?

  It seems like magic, but it's all by design. But given that the internet, just as you're describing it, the infrastructure seems seemingly everywhere. And then with the wireless component and satellites involved, how do you even shut down something like that?

• 7:08Speaker 05

  It really depends. The way connectivity and infrastructure is organized in various country by country. And so the key word here really is centralization. How much the connectivity infrastructure is centralized. So you might find some countries have mainly a big state telecom as a network operator, or a handful of operators. In other countries, you will find dozens who are densely connected and can leverage many different entry and exit points of traffic in the country or from the country to the rest of the world.

• 7:45Emily Kwong?

  And in Iran, is the internet infrastructure fairly centralized?

• 7:49Speaker 05

  It is, yes. And the government for years has worked also on making sure that they could have a certain degree of control on how the traffic flows and through which systems, which intermediate nodes, which links.

• 8:06Emily Kwong?

  Yeah. And going back to you, Amanda, you and Alberto learned about the internet outages through your work together on IOTA, this research project. Why is it important that something like IOTA exists?

• 8:18Speaker 02

  Yeah, so IOTA, it provides a public service for people to look at internet connectivity measurements anywhere in the world and see if their internet is connected, what's down, where is it down, how long has it been down? So it provides data that's Hopefully, people can get insights from. Hopefully, it's actionable data on Internet connectivity globally.

• 8:42Emily Kwong?

  Now, you measure Internet connectivity using three main signals. Can you describe each of those three signals and what they tell you about whether the Internet is flowing or not in a place? Starting with the first signal, router announcements. What are those?

• 8:57Speaker 05

  Yep. So Iranian networks announce the fact that they are reachable and will say, well, if you want to talk to these certain sets of IP addresses, just talk to me and I'll take care of delivering the traffic. That doesn't mean that the traffic will be delivered. The other one is also very simple. It's active probing. We basically constantly ping networks all over the world. And the third one is basically a form of network traffic pollution that constantly exists on the Internet. And we learn to cleanse this noise and use it as a liveness signal that is coming from different countries, different regions, and different network operators. So we call it telescope traffic because it's captured through a research infrastructure

• 9:40Speaker 05

  that by analogy with astronomy is being called network telescopes.

• 9:45Emily Kwong?

  And to be clear, Iran has shut down the Internet before, notably during protests in 2019. There were also mass casualties. This is known by some in Iran as Bloody November. Did IOTA's tools pick up on a drop in Internet connectivity back then? Is the government using any different tactics this time?

• 10:04Speaker 02

  Yeah. In 2019, you do see routing announcements go down to, say, 60%. So they were using this blunt force tool to take away connectivity, and they weren't able to do anything more sophisticated, like whitelisting with the white Sims or just providing access to certain people. So they've become more sophisticated in how they're implementing their shutdowns so that they can keep online what they want to keep online.

• 10:30Emily Kwong?

  What do you guess they're doing?

• 10:32Speaker 02

  Well, I think they want to be able to communicate as government officials. And I think they also want to control information. So we, I think, certain journalists get white Sims. So certain people who are trusted information sources are allowed to have connectivity.

• 10:51Speaker 02

  Also, I don't know that we're seeing this right now, but with the Women Life Freedom Movement in 2022, they were just shutting down mobile connectivity. And that was to mitigate against the economic cost of these shutdowns. Because when you're taking everything down, the economy is going to be affected. So being able to be more precise with how you implement this and be more sophisticated, you're definitely increasing some of the costs that are, in a way, political costs as well.

• 11:19Emily Kwong?

  With the innovation of satellite internet, is there some internet infrastructure that's just beyond the government's reach? That no matter what those in power want to do, the internet will still find a way? Is this like a race between governments and internet infrastructure?

• 11:35Speaker 05

  That's a really tough question. I guess that's what we are trying to understand and study. The signal jamming that we were referring to earlier is an example of how...

• 11:47Emily Kwong?

  The signal jamming of Starlink.

• 11:48Speaker 05

  Yeah, for example, Starlink.

• 11:49Emily Kwong?

  The satellites owned by SpaceX, yeah.

• 11:51Speaker 05

  It's an example of how even this type of connectivity can be within reach of governments. It's really something that is evolving and under our noses. And we're all trying to understand how things will keep evolving.

• 12:08Emily Kwong?

  What is the value in this research for you both? In really understanding internet connectivity when it's shut down?

• 12:15Speaker 05

  The internet is relatively opaque, especially the internet infrastructure. And so there is a scientific aspect in trying to understand internet connectivity better and especially trying to understand when connectivity fails in general. Not only when governments order shutdowns, but also when large fractions of population experience outages for other reasons, like power outages.

• 12:40Emily Kwong?

  Sure, from like natural disasters and such, yeah.

• 12:43Speaker 05

  So to me, a big question is when, where, how the internet fails. And we still don't have precise answers to that question.

• 12:55Emily Kwong?

  Amanda, what about you?

• 12:56Speaker 02

  I mean, there's certainly questions about sovereignty, like sovereignty of a state and how the internet shows up in that. Ukraine was definitely coming to mind as Alberto was talking about. Centralized versus decentralized networks. And, you know, we saw Ukraine be much more resilient because of how decentralized their internet is.

• 13:20Emily Kwong?

  Oh.

• 13:21Speaker 02

  Yeah, I mean, different context, but still that.

• 13:23Emily Kwong?

  But that made a difference.

• 13:25Speaker 02

  Yeah, and then I think, you know, this question of how to participate in civic life and how to be able to not just mobilize around a protest, but mobilize resources in general, the internet is still playing a part in that.

• 13:41Emily Kwong?

  Given the the power of the internet in modern life, Amanda, what do people lose when they don't have access to the internet?

• 13:49Speaker 02

  Yeah, I mean, I think the first thing is is connection to loved ones. That's one of the first things we hear from our partners is you're trying to get a hold of your brother or your mother or your father, of where are you, are you safe? I think that's really one of the number one first things that you lose. And you lose the ability to use your whatever mapping app that you use to try and get to safety. You may lose access to your bank account. There's really so many things that you lose.

• 14:26Emily Kwong?

  As for Iran, estimates for when the internet will be fully restored range from days to weeks.

• 14:35Emily Kwong?

  If you want to learn more about what is happening in Iran, check out our show notes. We'll link to more NPR reporting. And follow us to stay up to date on the latest science behind the headlines. I'm Emily Kwong. Thank you for listening to Short Wave from NPR. See you tomorrow.

• 14:59Emily Kwong?

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