Iran's IPv6 blackout reveals the limits of authoritarian internet control
The regime can censor the old internet. It cannot censor the new one—so it switched it off entirely.
The graph flatlined at 8pm Tehran time. As crowds massed across Iranian cities, answering exiled Crown Prince Reza Pahlavi's call for demonstrations, Cloudflare's traffic monitors registered a 98.5 per cent drop in Iran's IPv6 address space. IPv4 fell too, but incompletely. The pattern told a story: Iranian censors could filter the older protocol. The newer one they simply killed.
Iran has cut its internet during protests before—during the 2019 "Bloody Aban" uprising, during the 2022 demonstrations following Mahsa Amini's death. But those blackouts were blunt instruments, severing all international traffic. This one was selective in a revealing way. The regime's filtering apparatus, built over two decades, apparently cannot handle IPv6's vast address space. Faced with traffic it could not parse, the government chose the crudest solution available: elimination.
The protesters in the streets, at least 36 of whom are now dead including six children, face a digital blackout. But the blackout is itself a confession. It says: we have reached the edge of what we can control.
The architecture of control
Iran's internet funnels through a single chokepoint: the Telecommunication Infrastructure Company, a state-controlled gateway for all international traffic. This bottleneck architecture lets the regime monitor, throttle, and block at will. Instagram and WhatsApp remain officially banned; Iranians reach them through VPNs that the government periodically crushes. In crisis, officials can reduce international bandwidth to a trickle—or sever it entirely.
Alongside this filtering capability, Iran spent twenty years building the National Information Network, a domestic intranet independent of the global web. Banking, ride-hailing, e-commerce—all run on internal infrastructure. When international connectivity vanishes, daily commerce theoretically continues. The government can calibrate: enough disruption to cripple protest coordination, not so much that the economy collapses.
Analysts call this "engineered degradation." It represents genuine sophistication. But it was built for IPv4.
IPv4, the protocol governing network addresses since the 1980s, offers roughly 4.3 billion unique addresses. A large number, but finite—cataloguable, blockable. Iranian censors can identify VPN servers, target specific ranges, analyse traffic patterns and disrupt them.
IPv6 is different. Its address space runs to hundreds of undecillions. Users can shift addresses rapidly. The scale defeats the catalogue-and-block approach that works for IPv4. Iranian censors apparently never solved this problem. When protests escalated, they faced a binary: unfiltered IPv6 connectivity, or none at all.
They chose none.
The satellite problem
A decade ago, this blackout would have worked. Video of security forces shooting protesters would never reach international media. Coordination tools would die. The regime could kill in darkness, as it did in November 2019, when an estimated 1,500 people died in a crackdown that largely escaped documentation.
That logic has collapsed. Somewhere between 20,000 and 100,000 Starlink terminals now operate inside Iran, smuggled across borders and sold for $700 to $3,000 on the black market. When Elon Musk announced in June 2025 that "the beams are on" over Iran, he activated coverage for terminals that had been accumulating since the 2022 protests. These devices bypass Iran's terrestrial chokepoint entirely, talking directly to SpaceX's constellation of low-earth orbit satellites.
The numbers remain tiny—perhaps 0.1 per cent of Iran's 89 million people. But significance exceeds penetration. Activists and journalists can transmit video to international audiences even during total terrestrial blackout. A protest movement can be cut off from its domestic coordination tools while still broadcasting to the world.
Iranian officials grasp the problem. They have spent years lobbying the International Telecommunication Union to force Starlink to geo-fence its service over Iranian territory. The effort has failed. The terminals themselves prove difficult to locate: Starlink's phased-array antennas use beamforming technology that creates narrow, directional signals rather than omnidirectional broadcast, minimising the electronic signature that authorities might track. And jamming has proven ineffective.
When Russia tried to jam Starlink in Ukraine during the early invasion, SpaceX pushed a software update that neutralised the attack within 24 hours. Dave Tremper, the Pentagon's director of electronic warfare, called the response "eyewatering"—faster and more agile than anything in the US military's own arsenal. If Russia, with decades of electronic warfare experience and sophisticated doctrine, cannot reliably disrupt Starlink, Iran almost certainly cannot.
This creates a paradox that Iranian security analysts have themselves acknowledged. Every blackout advertises Starlink. When the regime demonstrates the fragility of terrestrial connectivity, it makes the case for satellite terminals that bypass terrestrial chokepoints. One analyst told IranWire that "a 'kill switch' is the best advertisement for Starlink." The more aggressively the regime exercises control over what it can reach, the more valuable become the systems it cannot.
Sieves, not walls
The contest between Iranian censorship and satellite internet echoes one that lasted forty years.
When the Cold War began, the Soviet Union devoted extraordinary resources to blocking Western radio. Voice of America started transmitting to the USSR in 1947. By 1948, Soviet authorities were jamming it. At the system's peak, roughly 1,700 jamming stations operated across Soviet territory, burning 45 megawatts of power. The Soviets spent more to block Voice of America than America spent to broadcast it.
The jamming never fully worked. Radio waves behave capriciously. Atmospheric conditions shift. Determined listeners could find frequencies where the signal came through. They learned to position radios near windows, to listen late at night when jammers sometimes reduced power, to travel outside cities where coverage thinned. An estimated third of Soviet urban adults listened to Western broadcasts regularly.
As one Reagan-era assessment put it: "Jamming is more like a sieve than a wall."
The parallel with Iran is structural. An authoritarian state pours resources into chokepoint control—jamming stations then, internet gateways now—while information routes around the blockage. Radio waves crossed the Iron Curtain by bouncing off the ionosphere, exploiting physics that jammers could not master. Starlink signals cross Iran's censorship wall by bouncing off satellites, exploiting a transmission path that no terrestrial authority can intercept.
The Cold War's lesson should trouble Tehran. Soviet jamming ceased in 1988, under Gorbachev's glasnost. Three years later, the Soviet Union ceased to exist. Correlation is not causation; many factors killed communism. But the failure to control information was both symptom and accelerant—proof that the system could not adapt, and a force that eroded its legitimacy once citizens accessed alternative sources.
Two Irans
For the tens of millions without satellite access, the blackout is complete. Protesters in smaller cities—Malekshahi, where IRGC forces killed at least four people including a child on 3 January; Lordegan, where gunfire crackled through the streets—cannot easily reach international media. Families cannot call relatives abroad. Businesses dependent on international communications, already hammered by triple-digit inflation, take another blow.
The human toll compounds. At least 36 dead since demonstrations began on 28 December. More than 2,000 arrested. Six of the dead are children. Security forces have raided hospitals to seize wounded protesters, firing tear gas inside medical facilities, beating healthcare workers.
The regime's information control extends beyond infrastructure. In Kuhdasht, a western city where protests have raged, a young man named Amirhesam Khodayarifard was killed on the fourth day of demonstrations. Authorities withheld his body. The condition for its release: the family must appear on television and declare that Khodayarifard had been a Basij member, a regime volunteer. The family has refused. They cannot bury their son.
This is information control of a different kind—not the manipulation of packets, but the manipulation of narrative. Rewrite the dead as defenders of the state rather than opponents. Make martyrs impossible.
For those with satellite terminals, a different Iran exists. Video flows out showing protests in 285 locations across 92 cities. Journalists file reports. Opposition figures abroad coordinate with networks inside the country. The information asymmetry cuts both ways: the regime cannot control what the world sees, even as it controls what most Iranians see.
Which audience matters more? International attention generates diplomatic pressure, documents atrocities for future accountability. Domestic coordination sustains protests. The blackout may cripple the latter while failing to prevent the former—fragmenting the movement's ability to organise even as its violence is witnessed from outside.
The edge of control
The Iranian government's response to these protests reflects lessons learned from past crackdowns. Engineered degradation rather than total blackout. Calibrated disruption rather than severed connectivity. Balance the need to fragment protest coordination against the economic cost of disconnection; acknowledge that satellite terminals make total blackouts counterproductive.
The calculation may work. Previous Iranian uprisings—2009, 2019, 2022—were eventually crushed despite international attention. Security forces willing to shoot protesters have historically defeated unarmed crowds. The decisive questions—will security forces remain loyal? will economic pressure become unbearable? will some external shock intervene?—lie outside the domain of internet access.
But the episode illuminates something structural. The internet's architecture is migrating away from terrestrial chokepoints that states can dominate. IPv6 overwhelms filtering systems built for IPv4. Satellite broadband bypasses national gateways. Mesh networking and encryption create further routes around censorship. Each development erodes the Great Firewall model—Chinese, Iranian, Russian alike.
Iran's IPv6 blackout is not a display of strength. It is a boundary marker. Here, the regime's capability ends. On one side, the internet it can censor. On the other, the internet it cannot—so it simply switched off. That boundary will not hold. The address space will keep expanding. The satellites will keep multiplying. The architecture of the internet is evolving away from the architecture of control.
What happens in Tehran and Kuhdasht and Malekshahi depends on forces beyond technology. But the ground is shifting. And no blackout stops that.