armchairhacker 3 days ago

> A Brief, Incomplete, and Mostly Subjective History of Chinese Internet censorship and its countermeasures

https://danglingpointer.fun/posts/GFWHistory

Posted 6 days ago (https://news.ycombinator.com/item?id=44898892)

  • Alex-Programs a day ago

    Thanks for sharing this. I researched this for my A level project a few years ago, and this is a really neat cross reference. I didn't mention V2Ray as much.

gorgoiler 4 days ago

How is traffic controlled inside PRC? Is GFW a central hub for all traffic between all hosts? Or between residential ASNs and commercial ones only? In the UK and Iran a lot of censorship was implemented by leaning on ISPs at IP level (eg BT Cleanfeed) and with DNS blocks but I haven’t kept up to date with how networks might handle residential hosting. Maybe internal traffic is just all banned?

  • kotri 4 days ago

    > How is traffic controlled inside PRC?

    Unknown. I haven't seen any injected fake DNS or reset packets so far to domestic hosts. But there are rumors that Google's servers in Beijing (AS24424) was once black holed.

    > Is GFW a central hub for all traffic between all hosts?

    It's supposed to has centralized management system, but not a single hub.

    > Or between residential ASNs and commercial ones only?

    Yes, the injecting devices are deployed in IXPs, the AS borders. See <Internet censorship in China: Where does the filtering occur?>.

    > In the UK and Iran a lot of censorship was implemented by leaning on ISPs at IP level (eg BT Cleanfeed) and with DNS blocks but I haven’t kept up to date with how networks might handle residential hosting.

    I believe Iran has more centralized system like China controlled by Tehran.

    > Maybe internal traffic is just all banned?

    No, internal HTTPS traffic is not banned in that hour.

  • inemesitaffia 4 days ago

    It's in operators but managed by the regional government.

    So what's blocked differs by region

ch3nyang 4 days ago

Not only individuals, but also major companies were locked down. If this was a dry run for "certain measures" in the future, I can't believe how much of a blow it would cause to the economy. Therefore, I think this was more of a human error.

  • account42 4 days ago

    Determining the scope of the impact would also be part of such a dry run. And if it is meant to be used along some kind of military action then it's going to throw the economy into chaos anyway.

daft_pink 3 days ago

As an aside, it’s incredible how many internal chinese websites are completely unsecured with a certificate and don’t use HTTPS and require login.

  • [removed] 3 days ago
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kotri 4 days ago

Terrible, this is Internet curfew. It's not uncommon to imagine they'd shutdown Internet across border during any war (like against Taiwan).

  • outworlder 4 days ago

    > Terrible, this is Internet curfew.

    If you think this is bad...

    You can't even have a blog in China without authorization. It doesn't matter if you pay "AWS" for a machine. It won't open port 80 or 443 until you get an ICP recordal. Which you can only do if you are in China, and get the approval. It should also be displayed in the site, like a license plate. The reason "AWS" is in quotes is because it isn't AWS, they got kicked out. In Beijing, it is actually Sinnet, in Nginxia it's NWCD

    You can only point to IPs in China from DNS servers in China - if you try to use, say, Route53 in the US and add an A record there, you'll get a nasty email (fail to comply, and your ports get blocked again, possibly for good).

    In a nutshell, they not only can shutdown cross border traffic (and that can happen randomly if the Great Firewall gets annoyed at your packets, and it also gets overloaded during China business hours), but they can easily shutdown any website they want.

    • leroyrandolph 4 days ago

      I laughed when I saw "Nginxia", thinking it was a portmanteau of, well, nginx and wuxia, a Chinese fiction genre. Reality is much less funny when I looked up NWCD, and you likely just made a typo of Ningxia.

      • seeknotfind 3 days ago

        "Xia" would map to a single character (code point) in Chinese. For instance, in simplified Chinese, it could be 下 (xia, meaning down), 侠 (martial arts - like the xia in wuxia), or any number of other homophones. Since the characters are already combinatorial, I'm not sure a Chinese speaker would think of this as a portmanteau.

    • UltraSane 4 days ago

      AWS in China also doesn't have the Key Management Service, which leads to me to conclude it must be pretty secure.

      I added an A record for subdomain and pointed it at Chinese IP addresses. I wonder if I will get that angry email?

      • bawolff 4 days ago

        Or they just dont want to be put in the position of having to give out keys.

        I think the real paranoid people use cloudHSM.

      • Faaak 4 days ago

        Actually, they wouldn't really know unless this domain is used. I guess they check the `Host` header to get the domain that targeted this IP and then check where the MX are hosted.

    • Hizonner 3 days ago

      > You can only point to IPs in China from DNS servers in China - if you try to use, say, Route53 in the US and add an A record there, you'll get a nasty email (fail to comply, and your ports get blocked again, possibly for good).

      Wait what? So I can DoS any Web site in China by creating a rogue DNS record that points to its IP address, even under a completely unrelated domain? How would they even find those records?

      • hunter2_ 3 days ago

        I guess they would find it the moment someone in China using a Chinese resolver tries to resolve your rogue record, since that would recurse to one of the root mirrors in China, which presumably feeds this mechanism.

        Seems like a very minor speed bump in your plan, though: presumably something like https://www.chinafirewalltest.com would achieve that, or send a few emails for folks to click.

      • fc417fc802 3 days ago

        I wonder if this is actually tied to Chinese domains and Chinese run registrars? That way it would be easy to flag the usage of foreign nameservers and there's no DoS risk.

    • fulafel 3 days ago

      What about other protocols, could you run eg Gopher or NNTP? I guess IMAP could work as well.

    • kotri 4 days ago

      Not all Western companies comply with Beijing, like Route53, a name I've never heard of; Cloudflare seems to be most popular in China.

      But yeah, they can shutdown anything unless proxy server is widely used. as <Nearly 90% of Iranians now use a VPN to bypass internet censorship>.

      • darrenf 4 days ago

        AFAIK Route53 is AWS’s managed DNS product, not a company.

  • eastbound 4 days ago

    In fact, it’s a common tactic to do something unusual, in a recurrent way, so people aren’t alerted when it happens for real. (When the Mossad stole 7 boats from a French port (that they had fully paid), they prepared a few months in advance by having the pilots start the engines every night at 23:00, pretending they needed it against the cold temperatures. When they day came, they started the engines and left, no-one saw it coming).

    • vintermann 4 days ago

      It could also be a test to look for surprising things that break, in case they want to do this permanently at some later point.

      • woooooo 4 days ago

        Hanlon's and Occam's razors point to it being a mistake by the GFW operators, imo.

        If it's on purpose, I think you have the most likely motivation.

  • wkat4242 4 days ago

    Could you bring something like a starlink mini for backup i wonder? Id imagine this would be very worrying being stuck there as a foreigner in such a situation.

    • mryall 4 days ago

      Starlink connects you to the internet via a ground station in the country where you are registered, and the antenna will also only operate in an approved zone (depending on your country and account type). You cannot use it in China.

      • Tuna-Fish 4 days ago

        > Starlink connects you to the internet via a ground station in the country where you are registered

        Not true anymore.

        > and the antenna will also only operate in an approved zone (depending on your country and account type). You cannot use it in China.

        This is still correct.

    • patrakov 4 days ago

      You can still bring a foreign SIM card. 100% effective (via data roaming) at bypassing the firewall, but expensive.

      • lazide 4 days ago

        Oddly, many travel SIMs have started to route traffic through China. I used one in India that clearly routed through Hong Kong, and caused a lot of problems.

    • stevage 4 days ago

      Depends a lot whether Starlink decides to let you.

      • spwa4 4 days ago

        No it does not. Against a huge state adversary like China it does not matter. They have satellites looking down so they can quickly locate any starlink users. And then ...

        The only thing that could bypass is GPS + laser links (meaning physically aiming a laser both on the ground AND on a satellite). You cannot detect that without being in the direct path of the laser (though of course you can still see the equipment aiming the laser, so it doesn't just need to work it needs to be properly disguised). That requires coherent beams (not easy, but well studied), aimed to within 2 wavelengths of distance at 160km (so your direction needs to be accurate to 2 billionths of a degree, obviously you'll need stabilization), at a moving target, using camouflaged equipment.

        This is not truly beyond current technology, but you can be pretty confident even the military doesn't have this yet.

  • veunes 4 days ago

    The infrastructure for that kind of control clearly already exists. What's unclear is how coordinated or deliberate these events are versus being side effects of testing or internal changes

  • hackernewsdhsu 4 days ago

    That's what's so great about LoRA. Decentralized txt msgs, ultra cheap radios people run at home or wherever. $10-35USD ON AMAZON. Least txts get through.

    • phantomathkg 4 days ago

      It won't get you from where you are to China though.

      • wkat4242 4 days ago

        No but something like WSPR or FT8 would. Needs a license though.

    • kotri 3 days ago

      Local police already equipped with signal jammer cars. Usually only used in college entrance exam period. They also appeared in recent protest in Jiangyou city.

    • cedws 4 days ago

      Can you recommend a guide? I’m interested in trying it out.

      • Gigachad 4 days ago

        Look up Meshtastic. It’s kinda fun. Can chat with random people around you. But I don’t think it’s really that useful unless you have a really good spot like an antenna on your roof with no trees or buildings in the way.

  • [removed] 3 days ago
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Eddy_Viscosity2 4 days ago

The most depressing is that what happens in China, will eventually happen in the west too. I'm sure certain US, UK, and EU bureaucrats are already crafting campaigns about how this ability will 'save the children' and that it should be implemented immediately (politicians and certain other selected people will be exempt of course).

  • pas 4 days ago

    There's nothing inevitable about this. Civil society needs to organize, coordinate, and spend money on PR about this.

    Right now liberal people mostly sit back and wait for things to get better, it's not enough. (Also going and walking up and down is not really effective.)

    • int_19h 3 days ago

      It's inevitable because we've seen time and again that all it takes to get the public opinion behind this kind of thing is to talk about how it is needed to catch pedophiles and terrorists.

      And if you talk back? Why, you must be a pedophile or a terrorist, otherwise why would you have anything to hide?

      It's gotten bad enough that people here on HN - Hacker News! - non-ironically make more or less this argument.

    • Eddy_Viscosity2 3 days ago

      It is inevitable, because the means by which civil society can organize, coordinate, and spend money on PR about this, are all firmly in the control of a very few people. These same people are generally on the side of more centralized control, because they are the ones who will wield it.

    • lossolo 3 days ago

      > Right now liberal people mostly sit back and wait for things to get better

      First they came for the socialists, and I did not speak out because I was not a socialist.

      Then they came for the trade unionists, and I did not speak out because I was not a trade unionist.

      Then they came for the Jews, and I did not speak out because I was not a Jew.

      Then they came for me and there was no one left to speak for me.

      • Eddy_Viscosity2 3 days ago

        Precisely. Works every time. It's a like zero-day exploit on society.

      • lyu07282 3 days ago

        Well slightly updated version today would be: Immigrants, Anti-Zionists, Socialists, Homeless, Welfare recipients, ...

  • [removed] 3 days ago
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chickenzzzzu 4 days ago

Think of how many people who have remote jobs with American companies couldn't connect to their meetings while they "work from home" while secretly being in China!

Normally they have to fight VPN issues anyway, but having a sovereign state inject your packets is certainly a fun new one.

  • Shank 4 days ago

    Anyone operating in/around China who needs a real VPN has a service they pay for and use that isn't mainstream that isn't blocked (using V2ray or similar). There's a reason why Shadowrocket is the number 1 app on the app store. I'm sure there are a lot of cases of people using e.g., off-the-shelf VPN apps and have trouble, but power users in China are always running a VPN, usually to Japan, that doesn't have this problem.

    • chickenzzzzu 3 days ago

      How do you propose users in China will magically get around a nation state injecting packets?

      • appease7727 3 days ago

        That's literally what VPNs are for.

        If you aren't aware: a Virtual Private Network creates a fully encrypted link between you and a remote node. So long as your encryption keys are secure, there's no way for anyone (even a global superpower) to listen to or intrude on that connection. There is no possible way to break into this connection, even with the entire planet's computing resources.

        From the outside, all you can see is a stream of encrypted data between two nodes. You cannot tell where the traffic goes once it exits the VPN server or what it contains.

        The only way to compromise a VPN connection is the most straightforward and pedestrian: compromise the VPN host and directly spy on their clients with their own hardware.

        The GFW certainly can and has detected such encrypted streams and blocked them for being un-inspectable. With a VPN you can perfectly hide what you're doing and you can perfectly prevent intrusion. You cannot prevent someone noticing you're using a VPN. China can simply blanket ban connections that look like VPN traffic. But they cannot tell what you're doing with that VPN.

  • veunes 4 days ago

    How many people suddenly "lost internet" mid-meeting and had to blame it on their router...

  • lossolo 3 days ago

    > Normally they have to fight VPN issues anyway

    There are special virtual SIM cards that provide access to services from mainland China, as well as VPNs that function normally without issues. I used both while I was in China.

    • kotri 3 days ago

      Yeah, have used one. Mine was a downloadable eSIM and meant for foreign travelers with 1-week plan. It actually establishes an IPsec VPN to the origin country. Beijing dare not to block foreigners' roaming services.

  • ChrisMarshallNY 4 days ago

    I suspect those connections worked fine.

    It’s good to know the boss.

    • chickenzzzzu 4 days ago

      I definitely appreciate that a percentage of so called "employees" are actually just full fledged Chinese nationals, living permanently in China, paid a salary to pretend to be an American who had their identity stolen.

      But there absolutely is also a non-negligible number of Chinese and Indian nationals, who have some type of visa status in the US (especially a green card) who spend many months in their original countries making $200,000 or more per year while living like royalty in their home countries :)

      • bapak 4 days ago

        The green card isn't citizenship, you lose it if you don't live in the US. It's not like they don't know when you enter or exit the country.

  • tietjens 4 days ago

    How common can this really be? And what kind of companies? I’m finding it really hard to imagine this to be widespread.

    • Ayesh 4 days ago

      I live in a popular Digital Nomad friendly country, and myself included, work with Europe/American companies roughly matching their time zones.

      Now, the people I work with know that I'm not really located in the same time zone, but I know people who don't bother to mention it. I rarely get phone calls, but I have a roaming connection active for banking/OTP/etc. Plenty of cheap cafes with great WiFi (500mbps+ almost everywhere), and several times cheaper too.

    • gradientsrneat 2 days ago

      Microsoft was caught doing it for the US federal government, so presumably Chinese software engineers are working on other Microsoft products too.

      I'll just say Microsoft is not the only company doing that, and there are also Chinese-owned SAASes which American companies pay for.

    • chickenzzzzu 4 days ago

      Sadly much more common than it should be. The durations vary widely, but with the price of airline tickets and the nature of corporate software engineering jobs, it's extremely easy to self-justify a month abroad. The US government allows 6 months officially for green card holders.

      If it wasn't literally 10x cheaper to live abroad than it is to live in Seattle/San Jose, it wouldn't be as prevalent. And not to mention, the quality of life is often better at the 10x cheaper price as well.

      I can give you as much proof as you would like!

    • wkat4242 4 days ago

      Yeah if I'd sneak off to work from another place I'd pick somewhere really nice. Not China.

      • djtango 4 days ago

        China spans 9.6M km. It has some of the biggest and most modern megacities (Beijing, Shanghai, Chongqing, Shenzhen to name a few) and features ancient historical wonders like the Great Wall, Forbidden City and Terracotta Warriors.

        The nature spans salt lakes and rainbow mountains akin to South America, to the Northern Lights in Mohe down to karst formations of Guilin shared with Vietnam's Halong Bay.

        The cuisine is diverse and dishes popular in places like Xi'an reveal lasting influences dating back to the Silk Road.

        If you can't find "somewhere really nice" amongst the myriad people and locations you haven't tried.

      • dbetteridge 4 days ago

        Have you ever been to China?

        Because they have some of the most beautiful scenery and buildings I've seen and I've been to dozens of countries.

        Personally I wouldn't go there for remote work, because the internet interference is a pain but a holiday definitely.

        • wkat4242 3 days ago

          No I have not. And I never will unless their government gives up its autocratic tendencies. I would never submit to that. Because of that it doesn't matter how beautiful it is, for me it will not be a nice place to be.

      • chickenzzzzu 4 days ago

        You say that because you don't hold a Chinese or Indian passport. Now think of those who do, who have family obligations, food preferences, local bank accounts.

tiahura 2 days ago

Shouldn’t the rest of the world be blocking connections from China.

  • bell-cot 2 days ago

    That'd be somewhat more workable than blocking importation of anything made in China. Somewhat.

technics256 4 days ago

How would one get around this if they found themselves in such a situation?

  • est 4 days ago

    In this exact scenario, just use ports other than :443

    But GFW certainly had the capability to block all ports. So no one really knew.

  • molticrystal 4 days ago

    Well for starters recreate the situation and test out different approaches. Thanks to the detailed analysis that can be attempted.

    If I understand right, a good next step would would be with eBPF or some type of proxy ignore the forged RST+ACK at the beginning.

    Then it would come testing to see if sending a bunch of ACK packets, perhaps with sequence numbers that would when reconstructed could complete the handshake. Trying to send them alongside the SYN+ACK or even before if it can be predicted. Maybe try sending some packets with sequence id 0 as well to see what happens.

    • kotri 4 days ago

      > ignore the forged RST+ACK

      See <Ignoring the Great Firewall of China> in 2006. That won't work if RST/ACK was injected to both sides.

      > Then it would come testing to see if sending a bunch of ACK packets, perhaps with sequence numbers that would when reconstructed could complete the handshake. Trying to send them alongside the SYN+ACK or even before if it can be predicted. Maybe try sending some packets with sequence id 0 as well to see what happens.

      This is an interesting approach already being utilized, namely TCB desync. But currently most people tend to buy VPN/proxy services rather than studying this.

      • billy99k a day ago

        I've been using Astrill to bypass the GFW for almost a decade. It's a bit expensive, but worth it.

jart 4 days ago

[flagged]

  • JumpCrisscross 4 days ago

    > Imagine what people would say about Cloudflare if they had an hour long outage

    That Cloudflare had an outage. Not America.

    • flohofwoe 4 days ago

      > That Cloudflare had an outage. Not America.

      You probably mean the USA? After all, it was China and not Asia which was responsible for the incident ;)

      • spauldo 4 days ago

        In English, there is no continent named "America." It's unambiguously used to refer to the United States.

  • est 4 days ago

    outage would mean a connection timeout

    in this case, the connection works fine, some extra RST+ACK packets were delivered to your network on purpose

    • jart 4 days ago

      Which could easily be explained by a buggy rollout to their great firewall. What does China gain from intentionally blocking SSL for one hour?

      • physicles 3 days ago

        Data on the impact that such measures would have, should they decide to implement them in the future.

  • preisschild 4 days ago

    I mean... it got blocked by their censorship infrastructure, does it really matter if it only got misconfigured?

neuroelectron 4 days ago

[flagged]

  • veunes 4 days ago

    But "good reason" depends a lot on your perspective

  • preisschild 4 days ago

    Yeah, dont want their citizens to voice anti-CCP thoughts

  • rfoo 4 days ago

    Pretty sure it's an incident.