---
_id: '66270'
abstract:
- lang: eng
  text: 'In June 2025, Iran enacted a nationwide Internet shutdown, culminating its
    already strict censorship apparatus. While Internet shutdowns happen regularly,
    insights into these shutdowns are notoriously difficult to obtain: their timing
    is hard to predict, and measurements are often impossible. In this paper, we present
    unique measurements surrounding Iran’s 2025 Internet shutdown in June, which we
    acquired during a regular analysis of Iran’s censorship apparatus. We contextualize
    our findings of Iranian DNS, HTTP, TLS, and QUIC censorship during the shutdown
    with measurements from platforms such as Cloudflare Radar and user reports. Our
    measurements show that Iranian censorship changed before and after the shutdown,
    marking preparation and recovery periods. For instance, QUIC censorship went into
    effect before and stayed in effect after the shutdown, while DNS over TCP censorship
    was only present briefly before the shutdown and resumed working afterwards. We
    also measured general network instabilities, especially for UDP, after the shutdown
    and the disabling of certain middleboxes. Our findings indicate that the Iranian
    censor enforced its shutdown using fine-grained techniques instead of relying
    on an all-or-nothing blackout. We advertise for continued measurements of the
    Iranian censor and hypothesize that future shutdowns in censoring countries could
    be detected during their preparation phase.'
author:
- first_name: Anonymous
  full_name: Anonymous, Anonymous
  last_name: Anonymous
- first_name: Niklas
  full_name: Niere, Niklas
  id: '63563'
  last_name: Niere
- first_name: Felix
  full_name: Graf Lange, Felix
  id: '67893'
  last_name: Graf Lange
- first_name: Juraj
  full_name: Somorovsky, Juraj
  id: '83504'
  last_name: Somorovsky
  orcid: 0000-0002-3593-7720
citation:
  ama: 'Anonymous A, Niere N, Graf Lange F, Somorovsky J. Insights into an Iranian
    Internet Shutdown. In: ; 2026.'
  apa: Anonymous, A., Niere, N., Graf Lange, F., &#38; Somorovsky, J. (2026). <i>Insights
    into an Iranian Internet Shutdown</i>. Free and Open Communications on the Internet,
    Calgary.
  bibtex: '@inproceedings{Anonymous_Niere_Graf Lange_Somorovsky_2026, title={Insights
    into an Iranian Internet Shutdown}, author={Anonymous, Anonymous and Niere, Niklas
    and Graf Lange, Felix and Somorovsky, Juraj}, year={2026} }'
  chicago: Anonymous, Anonymous, Niklas Niere, Felix Graf Lange, and Juraj Somorovsky.
    “Insights into an Iranian Internet Shutdown,” 2026.
  ieee: A. Anonymous, N. Niere, F. Graf Lange, and J. Somorovsky, “Insights into an
    Iranian Internet Shutdown,” presented at the Free and Open Communications on the
    Internet, Calgary, 2026.
  mla: Anonymous, Anonymous, et al. <i>Insights into an Iranian Internet Shutdown</i>.
    2026.
  short: 'A. Anonymous, N. Niere, F. Graf Lange, J. Somorovsky, in: 2026.'
conference:
  end_date: 2026-07-24
  location: Calgary
  name: Free and Open Communications on the Internet
  start_date: 2026-07-20
date_created: 2026-07-05T20:10:58Z
date_updated: 2026-07-05T20:11:03Z
ddc:
- '006'
file:
- access_level: closed
  content_type: application/pdf
  creator: nniklas
  date_created: 2026-07-05T20:08:45Z
  date_updated: 2026-07-05T20:08:45Z
  file_id: '66271'
  file_name: foci-2026-0016.pdf
  file_size: 539622
  relation: main_file
  success: 1
file_date_updated: 2026-07-05T20:08:45Z
has_accepted_license: '1'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://www.petsymposium.org/foci/2026/foci-2026-0016.pdf
oa: '1'
status: public
title: Insights into an Iranian Internet Shutdown
type: conference
user_id: '63563'
year: '2026'
...