Social networks being slowed down

Internet censorship all around the world Turkey
2

I’ve made some experiments on mobile Turkcell, here’s what I found:

  1. Connections are being slowed down, not blocked completely
  2. Slow down happens by SNI — so using “allowed” SNI and connecting to Facebook balancers works fine
  3. When connecting without SNI, connection is only slowed down if there were connections to that IP with slowed down SNIs, for example:
# 1.1.1.1 is not associated with Facebook, so it’s not slowed down yet
# time curl -qs https://1.1.1.1 >/dev/null
real    0m 0.91s
# now connect to 1.1.1.1 with a slowed down SNI
# time curl -qs https://facebook.com --resolve facebook.com:443:1.1.1.1 >/dev/null
Command exited with non-zero status 60
real    0m 7.75s
# try connecting to 1.1.1.1 without SNI again, and now it’s slowed down
# time curl -qs https://1.1.1.1 >/dev/null
Command exited with non-zero status 92
real    0m 17.77s

After reconnecting to network, this association is reset (so 1.1.1.1 is not slowed down after toggling airplane mode on and off).
I don’t know if it’s because I go to a different instance of filters, or they’re simply always start from clean state.

EDIT: most likely it always starts with a clean state, since same happens for facebook.com’s IP:

# time curl -k https://157.240.238.35
real    0m 0.87s
# time curl https://facebook.com 
real    0m 11.05s
# time curl -k https://157.240.238.35
curl: (92) HTTP/2 stream 1 was not closed cleanly before end of the underlying stream
Command exited with non-zero status 92
real    1m 1.32s
  1. it’s a different mechanism from one used for blocked websites — when doing the same as in step 3 with pornhub.com, 1.1.1.1 doesn’t become blocked or slowed down
  2. HTTP seems to work fine, and only HTTPS seems to be slowed down — but I’m not sure since I don’t know how to test this one properly