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VPN blocking
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VPN blocking is a technique used to block the encrypted protocol tunneling communications methods used by virtual private network (VPN) systems. Often used by large organizations such as national governments or corporations, it can act as a tool for computer security or Internet censorship by preventing the use of VPNs to bypass network firewall systems.
Description
[edit]Blocking VPN access can be done a few different ways. Ports that are used by common VPN tunneling protocols, such as PPTP or L2TP, to establish their connections and transfer data can be closed by system administrators to prevent their use on certain networks. Similarly, a service can prohibit access by blocking access from IP addresses and IP address ranges that are known to belong to VPN providers.[1][2] Some governments have been known to block all access to overseas IP addresses, since VPN use can involve connecting to remote hosts that do not operate under that government's jurisdiction.[3]
As organizations have ramped up efforts to block VPN access which bypasses their firewalls, VPN providers have responded by utilizing more sophisticated techniques to make their connections less conspicuous. For instance, as the Chinese government began using deep packet inspection to identify VPN protocols, the firm Golden Frog began scrambling OpenVPN packet metadata for its popular VyprVPN service in an attempt to avoid detection.[4]
Government use
[edit]China
[edit]Chinese internet users started reporting unstable connections in May 2011 while using VPNs to connect to overseas websites and services such as the Apple App Store.[5] Universities and businesses began issuing notices to stop using tools to circumvent the firewall.
In late 2012, companies providing VPN services claimed the Great Firewall of China became able to "learn, discover and block" the encrypted communications methods used by a number of different VPN systems.
In 2017, telecommunications carriers in China were instructed by the government to block individuals' use of VPNs by February 2018.[6]
In 2024, VPNs were frequently inaccessible during the Two Sessions.[7]
India
[edit]In 2022, the government of India stated VPN providers must log a variety of user data for a minimum of five years. Due to the new ruling, many VPN service providers removed their physical servers from India and instead operate virtual servers, allowing users to still connect to India locations but without falling under the jurisdiction of Indian law.[8]
Iran
[edit]The government of Iran began blocking access to non-government sanctioned VPNs in March 2013,[9] a few months prior to the 2013 elections, to "prosecute users who are violating state laws" and "take offenders to national courts under supervision of judiciary service". Use of VPNs approved by the government reportedly led to surveillance and inspection of private data.[10]
Russia
[edit]In July 2017, the State Duma passed a bill requiring the Internet providers to block websites that offer VPNs, in order to prevent the spreading of "extremist materials" on the Internet.[11][12] It is unclear exactly how Russia plans to implement the regulation; though it seems like both the Federal Security Service (FSB) and ISPs will be tasked with identifying and cracking down on VPNs. In November 2017, BBC made it clear that Russia has not banned VPN usage entirely. VPN usage is only banned when attempting to access sites already blocked by Roskomnadzor or Russia's governing body for telecommunications and mass media communications.[13] Using a VPN for business or personal reasons to access legal sites in Russia is permitted.[14]
Russia has banned various VPN service providers in 2021[15] and forced Google to delist VPN websites even while Russians continue to download VPNs.[16]
Syria
[edit]The government of Syria activated deep packet inspection after the uprising in 2011 in order to block VPN connections.[17] The censorship targeted different VPN protocols like OpenVPN, L2TP and PPTP.
Pakistan
[edit]The government of Pakistan issued a notice to VPN providers to register their IPs, otherwise their VPN service will be blocked like in China.
Turkey
[edit]In an attempt to curb the use of social media by its citizens, the government of Turkey has considered the complete ban of VPN apps. The Nationalist Movement Party proposed a bill covering such a ban in July 2020.[18][19][20]
VPN blocking by online services
[edit]Hulu
[edit]In an attempt to stop unauthorized access from users outside the United States, Hulu began blocking users accessing the site from IP addresses linked to VPN services in April 2014. In doing so, however, the company also restricted access from legitimate U.S.-based users using VPNs for security reasons. VPN providers such as VikingVPN, NordVPN and TorGuard stated that they would seek ways to address this issue for their customers by speaking directly to Hulu about a resolution and rolling out more dedicated IP addresses, respectively.[21]
Netflix
[edit]Netflix came under pressure from major film studios in September 2014 to block VPN access, as up to 200,000 Australian subscribers were using Netflix despite it not being available yet in Australia.[22] VPN access for Netflix has, like other streaming services, allowed users to view content more securely or while out of the country. Netflix users have also used VPNs as a means of bypassing throttling efforts made by service providers such as Verizon. It is also important to note that all VPNs might slow down internet connection when trying to stream Netflix; however, there are cases where using a VPN might improve connection if a user's ISP has been throttling Netflix traffic. As of June 2018, the Netflix VPN and proxy ban is still active. The CEO of Netflix, Reed Hastings made a comment in 2016 about the VPN market as a whole; “It’s a very small but quite vocal minority. It’s really inconsequential to us.”[23]
BBC iPlayer
[edit]The BBC started blocking users connecting via VPNs in October 2015.[24] The BBC is able to detect VPN connections by monitoring the number of simultaneous connections coming from each IP address. If the number of connections from the same IP becomes abnormal the BBC will block future connections from the offending IP address.
BBC iPlayer remains unavailable to UK TV Licence holders connecting from other EU countries.[25] The BBC said that it was "interested in being able to allow UK licence fee payers to access BBC iPlayer while they are on holiday, and welcome the European Union regulation to help make this feasible."[26]
Threads
[edit]Meta's Threads platform started blocking users from the European Union who used VPNs to bypass the access restriction to the service stemming from the privacy concerns of the app.[27] However, as of December 14, 2023,[needs update] the platform was accessible to users in the European Union.[28]
See also
[edit]References
[edit]- ^ "VPN and Proxy Detection API". Focsec. Retrieved 2025-07-21.
- ^ "IP2Proxy™ IP-ProxyType-Country Database [PX2]". www.ip2location.com. Retrieved 2016-06-12.
- ^ Lam, Oiwan (13 May 2011). "China: Cracking down circumvention tools".
- ^ Toombs, Zach. "China's Censors Take on Virtual Private Networks". Retrieved 13 November 2014.
- ^ Arthur, Charles (13 May 2011). "China cracks down on VPN use". The Guardian.
- ^ China Tells Carries to Block Access to Personal VPNs by February. Bloomberg. 2017-07-10
- ^ "China Tightens Grip Over Internet During Key Political Meeting". Voice of America. 2024-03-10. Retrieved 2024-03-26.
- ^ Singh, Manisha (17 June 2022). "Explainer: New VPN rules, why companies are upset and what they mean for you". Retrieved 16 August 2022.
- ^ Torbati, Yeganeh (2013-03-10). "Iran blocks use of tool to get around Internet filter". Reuters.
- ^ Shwayder, Maya (2013-03-11). "Cyber-Rebels See Way To Get Around Iran's VPN Internet Block". International Business Times.
- ^ "Russian parliament bans use of proxy Internet services, VPNs". Associated Press. July 21, 2017.
- ^ "Russia: New Legislation Attacks Internet Anonymity". Human Rights Watch. 2017-08-01. Retrieved 2017-08-01.
- ^ "Explainer: What is Russia's new VPN law all about?". BBC News. 2017-11-01. Retrieved 2020-12-06.
- ^ Idrisova, Ksenia (2017-11-01). "What is Russia's new VPN law all about?". Retrieved 2019-05-13.
- ^ "Russians' demand for VPNs skyrockets after Meta block". Reuters. 2022-03-14. Retrieved 2022-04-07.
- ^ Forbes (2022-03-21). "Russia Forcing Google To Delist VPN Websites, But 400,000+ Russians Are Downloading VPNs Daily". Forbes. Retrieved 2022-04-10.
- ^ Kim, Kuinam J.; Chung, Kyung-Yong (2012-12-12). IT Convergence and Security 2012. Springer Science & Business Media. ISBN 9789400758605.
- ^ "Turkey plans to restrict social media and block VPN services". VanillaPlus. 2020-07-30. Retrieved 2020-10-19.
- ^ "Turkey's ruling coalition partner calls for block on VPN services ahead of vote on social media bill". Ahval. Retrieved 2020-10-19.
- ^ "Turkey plans to restrict social media and block VPN services". The EE. 2020-07-30. Retrieved 2020-10-19.
- ^ Van Der Sar, Ernesto. "Hulu Blocks VPN Users Over Piracy Concerns".
- ^ Maxwell, Andy. "VPN Users 'Pirating' Netflix Scare TV Networks".
- ^ "Canada Netflix users complain as access to U.S. service blocked". Reuters. 2016-04-20. Retrieved 2019-05-13.
- ^ Thomson, Iain (19 Oct 2015). "BBC shuts off iPlayer to UK VPNs, cutting access to overseas fans". www.theregister.co.uk. Retrieved 2019-05-13.
- ^ Smith, Mat (2 April 2018). "Brits (still) can't stream BBC iPlayer abroad". Engadget. Retrieved 2019-05-13.
- ^ Sweney, Mark (2018-04-02). "From sofa to sunbed: holidaymakers can see British pay-TV abroad". The Guardian. ISSN 0261-3077. Retrieved 2019-05-13.
- ^ Mehta, Ivan (2023-07-14). "Meta confirms it is blocking EU-based users from accessing Threads via VPN". TechCrunch. Retrieved 2023-07-14.
- ^ "Threads: Meta's rival to Elon Musk's X launches in EU". BBC News. 2023-12-14. Retrieved 2023-12-19.
VPN blocking
View on GrokipediaTechnical Foundations
Core Mechanisms of Detection and Blocking
VPN blocking primarily relies on identifying and obstructing traffic routed through virtual private network servers, which encapsulate user data to mask origins and bypass restrictions. Core detection mechanisms include blacklisting known IP addresses associated with VPN providers, as networks maintain databases of such addresses derived from public registries and traffic monitoring.[1] This approach effectively prevents connections from established commercial VPN services by denying inbound or outbound traffic from flagged IP ranges, though it requires continuous updates to counter IP rotations by providers.[10] Deep packet inspection (DPI) constitutes a more advanced method, enabling routers and firewalls to scrutinize the contents of data packets beyond mere headers to identify VPN-specific signatures. DPI systems analyze payload patterns, such as encryption headers or protocol handshakes characteristic of OpenVPN or IPsec, allowing differentiation between standard internet traffic and tunneled VPN flows.[11] For instance, DPI can detect anomalies like uniform packet sizes or high entropy indicative of encrypted tunneling, even when protocols mimic HTTPS.[12] Deployed in national firewalls, this technique processes traffic in real-time to throttle or drop suspicious packets, though it demands significant computational resources and can be evaded by obfuscation tools.[13] Traffic analysis complements DPI by examining aggregate flow behaviors without full decryption, focusing on metrics like packet timing, volume bursts, or directional imbalances atypical of direct web browsing. Machine learning models trained on labeled datasets achieve high accuracy in classifying VPN usage, with studies reporting detection rates exceeding 95% for protocols like WireGuard through features such as inter-arrival times and payload lengths.[14] Active probing further verifies suspicions by simulating client connections to potential VPN endpoints, confirming server responses that reveal tunneling capabilities.[13] Port blocking targets common VPN entry points, such as UDP port 1194 for OpenVPN, but proves less effective against configurable or non-standard ports.[10] These mechanisms often integrate in layered defenses, where initial IP filters reduce load on DPI engines, enhancing scalability for high-volume networks. Empirical evaluations indicate that combining multiple methods yields robust blocking, with DPI and traffic analysis proving resilient against protocol updates as of 2024.[15] However, advancements in VPN obfuscation, such as chameleon-like protocol emulation, continually challenge detection efficacy, underscoring an ongoing technological arms race.[16]Common Protocols and Vulnerabilities Targeted
OpenVPN, a prevalent open-source protocol, operates primarily over UDP port 1194 or TCP port 443 to mimic HTTPS traffic, yet remains vulnerable to deep packet inspection (DPI) through identifiable handshake sequences, byte patterns, and packet size distributions that distinguish it from standard web traffic. A 2024 study analyzing traffic from one million users demonstrated that passive DPI fingerprinting combined with active probing achieves approximately 85% detection accuracy for OpenVPN flows with negligible false positives, facilitating targeted blocking by dropping connections upon confirmation of protocol-specific server responses.[17][11] WireGuard, favored for its efficiency and use of UDP port 51820, exposes vulnerabilities via characteristic initial datagram bytes (e.g., starting with 0x01000000 in un-obfuscated implementations) and consistent packet entropy profiles, allowing DPI systems to classify and block it as anomalous UDP traffic rather than legitimate protocols like DNS.[11] This susceptibility has prompted implementations of TCP fallbacks or wrappers, though advanced DPI persists in identifying underlying structures through behavioral analysis. IKEv2/IPsec, relying on UDP ports 500 for IKE negotiation and 4500 for NAT traversal, is targeted via DPI recognition of its encapsulation headers, ISAKMP payloads, and ESP packet formats, which exhibit distinct fragmentation and authentication patterns not typical of unencrypted UDP flows.[11] Protocols like L2TP/IPsec further compound issues with fixed UDP port 1701 dependencies and IPsec overhead, rendering them prone to port-based blocking and DPI signature matching that exploits their layered tunneling without inherent obfuscation.[18]| Protocol | Key Detection Signatures | Primary Vulnerabilities Exploited |
|---|---|---|
| OpenVPN | TLS-like handshakes, specific byte strings | Lack of dynamic obfuscation; fixed pattern entropy[17] |
| WireGuard | Initial UDP bytes, uniform packet sizing | Minimal overhead exposes protocol fingerprints[11] |
| IKEv2/IPsec | ISAKMP headers, ESP encapsulation | Port dependencies and payload structure rigidity[11] |
| L2TP/IPsec | UDP 1701 port, IPsec AH/ESP markers | Firewall traversal failures; static tunneling[18] |
