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Can the internet be censored from the ISP itself? And what to do if the internet is censored by my ISP?

Even TOR is not showing me the results I want: I had previously searched for the same keywords and got results but now I don't get anything.

I have tried a premium VPN and TOR to browse content but both of them fail. How can I bypass my ISP censorship?

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    Hello and welcome to Security.SE! Could you clarify what you mean by "not showing you the results you want" and not getting anything?
    – Yuriko
    Oct 17 at 3:07
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    We need more information on what you mean by "finding website": is it about some specific Google results not showing up anymore? Websites suddenly offline?
    – Yuriko
    Oct 17 at 4:05
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    If it is an issue with search results from an encrypted source (Google, TOR), then your ISP shouldn’t normally be able to alter them, except if your own machine is corrupted. It is more likely that the results were de-listed (for any reason), or simply got lower priority and other results appear first. Note that Google keeps an history of your searches, maybe you could still find that result there? Or even from your own browser history?
    – Didier L
    Oct 17 at 11:40
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    Are other people able to perform these same searches? Can you give an example of a search that failed?
    – Barmar
    Oct 17 at 14:20
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    This question is too unclear. I had previously searched for the same keywords and got results but now I don't get anything -- this suggests that a search engine was used. Which one? What was the exact or approximate query terms you used when results were all good? (See your history to find that). What exact search query did you use this time? A lot of this question depends upon the subject matter of search query. If the earlier search results from non-TOR/VPN returned illegal content (or region-specific content) than TOR/VPN results are likely to vary.
    – Firelord
    Oct 17 at 15:13

6 Answers 6

50

Generally speaking, your ISP can't censor Tor or VPNs except by blocking them altogether.

Since you are also "censored" when using Tor and a VPN, it's more likely that either the search engine is censoring your results (if you are using the same one) or else the thing you are trying to find doesn't exist on the Internet any more.

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    There is also a possibility of it happening on the client side.
    – n0rd
    Oct 17 at 23:27
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    "Censoring" implies intent, but another possible (and more likely) reason is that search engines shift the priorities of pages around frequently, and the page OP is looking for just happened to get shifted down. Oct 18 at 3:01
  • I'm no expert: what if a rogue root certificate is installed on the device?
    – Gruber
    Oct 18 at 18:32
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    @Gruber Tor and VPNs use their own separate systems
    – user253751
    Oct 18 at 18:37
  • OP appears to be from India. There are some new rules about VPN use: cloudwards.net/vpn-ban-in-india
    – Nav
    Oct 20 at 7:34
17

Yes, an ISP can restrict your access to the internet. And they do it.

Here are some examples of how they can do it. I added a quick list at the end of what one can do to prevent their ISP to tamper with their connection.

Also, note that your ISP is not the only component that can implement censorship. Google could be forced to delist results (eg: after a DMCA takedown notice), and any website can be asked to remove content - legally or illegaly.

Simple blacklist

An ISP can simply have a list of domain names or IP addresses that needs to be blocked. Anytime a request comes to their network for one of these IP address and/or domain name, the ISP can simply drop the connection.

An ISP could also make that decision based on the content of the data transmitted if it is not encrypted.

DNS resolution

When browsing the internet, you usually rely on domain name, such as security.stackexchange.com. However, while convenient for you, your computer will need to request the IP address associated with the domain names. This service uses the DNS protocol and is usually provided by your ISP.

This allows them to block or redirect access to some websites considered as illegal upon a court decision. Here's an example of a court decision instructing ISP to redirect the traffic to a website to a landing page.

IT IS FURTHER ORDERED that all ISPs [...] and any other ISPs providing services in the United States shall block access to the Website at any domain address known today. [...] The domain addresses and any Newly-Detected Websites shall be channeled in such a way that users will be unable to connect and/or use the Website, and will be diverted by the ISPs’ DNS servers to a landing page operated and controlled by Plaintiffs (the “Landing Page”) which can be reached as follows:

Domain: http://zira-usa-11025.org
IP Address: 206.41.119.81 (Dedicated)

Source: United King Film Distribution LTD, et al. v. Does 1-10, d/b/a Israeli-tv.com, 21 Civ. 11025 (KPF), Default Judgment And Permanent Injunction Order (Apr. 26, 2022)

BGP

BGP stands for Border Gateway Protocol and is used to interconnect different networks. An ISP can then reroute the traffic to another location, either to make a website unavailable, or to redirect the users to another server. (As seen with the DNS example.)

An example is when the Pakistani PCCW company rerouted traffic to Youtube upon a government request. As the link states, it had unforeseen side effects.

What can I do?

As your trafic initially goes through your ISP network, the main mitigations would be to prevent it from identifying your trafic as suspicious and blocking/redirecting it. A non-exhaustive list of countermeasures could be:

  • Not rely on your DNS provider (see below) which can easily be changed in most OS settings;
  • Use a proxy or VPN to reroute your trafic to a trusted network;
  • Use encryption between you and the service requested to avoid any content-based censorship;
  • Switch to another ISP that do not block the content you want to access.

I note that you are using Tor, which should mitigate some of these issues. We would need more information to understand what has been tampered with to make better assumptions on what's happening.

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    None of these seem like plausible explanations for what OP is experiencing, so while this answers the subject-line question "can they censor...?" in some way, I feel it's very misleading as an answer to OP's full question. Oct 17 at 13:42
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    Indeed, the OP says in the comments "I know that there are websites for what I am searching but google search and even onion search are not showing any results". This is not something an ISP can do, or at least that kind of censorship has nothing to do with their role as an ISP (in certain jurisdictions such as the EU everybody can demand Google to censor its results under certain circumstances after all).
    – Voo
    Oct 17 at 13:48
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    You suggested a VPN as a countermeasure, but they said they tried both VPN and TOR (which is essentially a fancier VPN) and it didn't work.
    – Barmar
    Oct 17 at 14:18
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    @Yuriko If you use VPN/TOR, the only thing the ISP can do is block them entirely, they can't censor the results.
    – Barmar
    Oct 17 at 14:54
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    It blocked the entire Internet. Censorship is generally more specific. It certainly couldn't be used to do the fine-grained censorship of search engine responses described in the question.
    – Barmar
    Oct 17 at 14:58
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Your ISP cannot censor the internet with anything finer than entire DNS hostname or IP address granularity. They cannot modify Google search results or interfere with your ability to use Google short of blocking Google entirely. They cannot modify the content of pages you visit.

Of course, the above is all under some basic key assumptions:

  • The url you're visiting is https:// not http://. In 2022 this should be a given, but there are still a very small number of sites that's not the case for.
  • You did not click through any invalid certificate warnings. This is very unlikely to happen - the ISP is not going to attempt stuff like this because plenty of users will not click through and the ISP will quickly be caught and get in trouble for trying.
  • You did not install any software provided by your ISP to put backdoors on your computer, often marketed as "malware protection" or "parental control" software. This kind of thing could very well setup your computer to accept fraudulent certificates the ISP (or rather some scummy partner of theirs) uses to impersonate sites and modify their contents. Never install software from an ISP - and that includes VPNs! Because VPNs are a second ISP. Any legitimate VPN will just give you configuration/credentials to install it through your operating system's normal VPN mechanisms, not custom branded software to install.

Unless you have installed sketchy software like what I mentioned above, I find it extremely unlikely that you're seeing any sort of censorship by your ISP or any other party. More likely, Google just delisted or buried whatever result you're looking for, for their own reasons. You could try searching from somebody else's computer/network to confirm this. Keep in mind that by default Google uses personalized search results, so it's possible that if you still have this on, their personalization for you changed such that they no longer think the same things are relevant to you. I would highly recommend turning off personalized results because of how frustrating it is when stuff like this happens as a result.

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    Unless you're using ECH, which I don't think anything supports yet, they can also see the SNI and censor based on that Oct 17 at 15:25
  • @Radvylf Programs - While what you said about SNI is technically correct, the way you said it is misleading. SNI only shows the base domain. If you go to Google to do a search, SNI shows Google, nothing else. There is no visibility into search terms or responses. SNI could be used to block complete access to Google, but not to censor particular searches. Oct 17 at 15:38
  • @user10216038 Yeah, sorry about that. Probably should've included a brief description of SNI. Oct 17 at 15:45
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    @RadvylfPrograms: SNI is still on the hostname level and the censorship capabilities are exactly the same as what you'd get from blocking DNS. There is no further granularity within the site, much less ability to alter or remove content. Oct 17 at 17:33
  • Is the rogue certificate issue valid also for Tor and/or TorBrowser?
    – Gruber
    Oct 18 at 18:35
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This does not sound like an ISP issue at all.

The search results that you get when you use a search engine are not something that your ISP has any control over at all, at least in normal cases. They are determined by the operator of the search engine.

It is possible that that search engine has removed those websites that you are looking for from its index, or ranked them lower, or that they have simply disappeared from the Web. If you actually still knew the URL of the website that you used to access and can't find anymore now, then you could try to access it again; if that works through Tor but not without Tor, then it could be an ISP issue, but from the facts you have given us, there is nothing that indicates that.

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While ISPs can and do collude with governments to block access to web sites, they have no capability to see and alter search engine queries in an encrypted connection.

Search engines, like Google, can and do block results by direction of various government entities.

If you suspect your search is being censored:

  1. Try a different search engine, like DuckDuckGo. Don't login to any of the search engines!

  2. Use a VPN that exits in another country. It may not be sufficient to simply use a VPN if there is a country wide restriction in place, the VPN exit needs to be at a location not subject to the restrictions.

  3. Tor is a special case of VPN but you still need to be sure the exit node is outside the country.

You said, "I have tried a premium VPN and TOR to browse content...". This implies that you have moved beyond search and are now having access problems. This is a different issue.

Access blocks can be implemented in various ways including SNI,DNS, BGP, IP, Others. Some of this can be ISP level, some higher infrastructure. In any case possible workarounds are the same, a VPN exit out-of-country. If the host server being blocked is In-Country you're probably screwed unless they offer an Onion Service.

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The ultimate crux of OPs question also comes down to this specific item: "I have tried a premium VPN and TOR to browse content but both of them fail. How can I bypass my ISP censorship?" (Yes, ISPs can filter, but not fine-grained filtering of searches over TOR/VPN).

You can bypass ALL censorship by, for example, using a colleague in another country who has a "jump server" setup. VPNs are awesome, but they don't always solve your issues; though, as others state, the ISP itself likely is not causing your specific issue, since it would typically block all or nothing. Sounds more like some client-side software on your own computer or network may be filtering things(?)

So, you wanted a solution: we use this solution many places: User from "blocked country" (UserX) has colleague in "non-blocked" country (UserY). UserY sets up a "jump server" to which UserX can connect over VPN. Once you are connected via RDP software such as "remotely," "TeamViewer," etc., then you are, effectively, 'inside' the "non-blocked/free" country; and you can browse or perform completely unfiltered searches. Compare this to using some of the other VPN methods where, in most cases, you are not always truly "in" the unblocked country; but you "appear to be" in the unblocked country (depending how the VPN & routing work).

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    What are examples of VPNs that only make you appear to be in another country?
    – schroeder
    Oct 18 at 13:17
  • "Other VPN methods" are only different in the way they're usually more popular and more likely to be tracked in one way or another. RDP/TeamViewer/SSH/OpenVPN/whatever are not inherently more secure, it's just that major service providers (or, potentially, censors) don't have your little server in the known VPN or datacenter list.
    – Lodinn
    Oct 18 at 14:26
  • Not saying 1 is more secure; I'm saying, 1. fire up VPN, 2. once on VPN, you're secure; so then RDP or remotely connect to a "Jump Server" for just this type of thing. Once you connect to my U.S. server, then you are, effectively, running completely from TN, U.S. or NY U.S., or wherever my server resides. I never mentioned specific VPN; just use a "jump server;" before you begin browsing. Some other VPNs "masquerade" as a pseudo-server; tunnel thru various routes; so you "appear to be" in the U.S. - that's how Onion/TOR routing work. @schroeder - that should answer your query also. Oct 18 at 14:39
  • @Lodinn - I hope that addressed your comment. The user asked for ways to get around any "local blocking," basically. Since some VPNs that use pseudo-servers via Onion routing are not truly "IN" another country; there may be ways that cause them to be blocked/filtered. Whereas, if you connect to VPN, then connect remotely to a jump server, then you're not subject to local ISP blocking in your region - unless they completely obliterate your remote VPN connection & session. :-) Oct 18 at 14:44

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