5 ms·

Doesn't really explain Why can email be sent from China to Gmail, only that it can. Is the GFW filtering only port 80?

schoen 10y ago
I was expecting this to be "why" as a policy matter, but instead it's a technical description (mostly about the fact that SMTP is different from HTTP, for people who might not appreciate that). I guess the idea may be that Chinese people are not supposed to have or use Gmail accounts, but are allowed to communicate with other people who do. (This isn't necessarily a super-bizarre distinction to imagine a government making; the cost of not being allowed to exchange e-mail with anybody on Gmail is really quite high.) Edit: also, people have told me that there is a legal restriction in China on the ability to listen on (some?) TCP ports or allow a hosting subscriber to do so (!) -- you're supposed to have a government license to have a TCP listener and your hosting provider or ISP can be punished for allowing you to operate one if you don't have the license. That means that Chinese Internet users couldn't easily set up their own personal mail servers free of government oversight and surveillance. So they can write to Gmail users all they like, but it may be trickier to receive a reply except via a government-approved mailserver.
- Cerium 10y ago
  Agreed, it is a technical explanation to political decisions. The Chinese government wants to be able to access the communications of their people. They can do that as long as their email providers are cooperative. There is no need to disrupt communications to ensure this is the case, they simply need to keep Chinese citizens from using uncooperative providers.
- gcr 10y ago
  Let's write a webpage-to-gmail proxy! Send an email with a subject like http://news.ycombinator.com/ http://news.ycombinator.com/ to a special email address and it will reply with the text of that page in the body of the email.
  - wildfire 10y ago
    There are a whole bunch already! http://www.faqs.org/faqs/internet-services/access-via-email/ http://www.faqs.org/faqs/internet-services/access-via-email/ Probably worth some karma to update this 14 year old document too.
  - vijayp 10y ago
    oh man, I remember browsing FTP servers over email back in the early 1990s, when I had email access but not FTP access. It was incredibly slow and typos were to be avoided at all costs! https://en.wikipedia.org/wiki/FTPmail https://en.wikipedia.org/wiki/FTPmail
  - skoczymroczny 10y ago
    Sounds like that script Stallman is using.
marme 10y ago
no they filter many different ports and do deep packet inspection on anything that is not encrypted and will block if contains certain content. There is a set list of banned words that will get content blocked instantly. VPN traffic is usually blocked once it is identified as being unlicensed vpn, you need a license to run a vpn server. So these vpn companies will rotate their ips multiple times per month and have special clients that keep the list updated just to avoid the GFW
netsharc 10y ago
It's a really long and uninteresting post for the tl;dr "port 25 is not being blocked by the firewall". Although he should've tried using some bad keywords, but that seems to be beyond his level of research.

I was expecting this to be "why" as a policy matter, but instead it's a technical description (mostly about the fact that SMTP is different from HTTP, for people who might not appreciate that). I guess the idea may be that Chinese people are not supposed to have or use Gmail accounts, but are allowed to communicate with other people who do. (This isn't necessarily a super-bizarre distinction to imagine a government making; the cost of not being allowed to exchange e-mail with anybody on Gmail is really quite high.) Edit: also, people have told me that there is a legal restriction in China on the ability to listen on (some?) TCP ports or allow a hosting subscriber to do so (!) -- you're supposed to have a government license to have a TCP listener and your hosting provider or ISP can be punished for allowing you to operate one if you don't have the license. That means that Chinese Internet users couldn't easily set up their own personal mail servers free of government oversight and surveillance. So they can write to Gmail users all they like, but it may be trickier to receive a reply except via a government-approved mailserver.

Cerium 10y ago
Agreed, it is a technical explanation to political decisions. The Chinese government wants to be able to access the communications of their people. They can do that as long as their email providers are cooperative. There is no need to disrupt communications to ensure this is the case, they simply need to keep Chinese citizens from using uncooperative providers.
gcr 10y ago
Let's write a webpage-to-gmail proxy! Send an email with a subject like http://news.ycombinator.com/ http://news.ycombinator.com/ to a special email address and it will reply with the text of that page in the body of the email.
- wildfire 10y ago
  There are a whole bunch already! http://www.faqs.org/faqs/internet-services/access-via-email/ http://www.faqs.org/faqs/internet-services/access-via-email/ Probably worth some karma to update this 14 year old document too.
- vijayp 10y ago
  oh man, I remember browsing FTP servers over email back in the early 1990s, when I had email access but not FTP access. It was incredibly slow and typos were to be avoided at all costs! https://en.wikipedia.org/wiki/FTPmail https://en.wikipedia.org/wiki/FTPmail
- skoczymroczny 10y ago
  Sounds like that script Stallman is using.

marme 10y ago

no they filter many different ports and do deep packet inspection on anything that is not encrypted and will block if contains certain content. There is a set list of banned words that will get content blocked instantly. VPN traffic is usually blocked once it is identified as being unlicensed vpn, you need a license to run a vpn server. So these vpn companies will rotate their ips multiple times per month and have special clients that keep the list updated just to avoid the GFW

netsharc 10y ago

It's a really long and uninteresting post for the tl;dr "port 25 is not being blocked by the firewall". Although he should've tried using some bad keywords, but that seems to be beyond his level of research.