[Cake] how to ecn again on osx and ios!!!

[Dave Taht <dave.taht@gmail.com>]

The additional sysctl required to re-enable ecn negotiation always is

sudo sysctl -w net.inet.tcp.disable_tcp_heuristics=1

See also:
https://github.com/apple-opensource/xnu/blob/master/bsd/netinet/tcp_cache.c#L164

It disables mptcp and tfo, which for purposes of even basic worldwide
testing of the survival of the ect(0) and ect(1) codepoints, don't
really matter. I am delirious with joy to be able to test this stuff
again from devices more people have, and I hope y'all turn it on for a
while, on ethernet/wifi and lte, get a bunch of captures and see what
happens in day to day use. I would so love packet captures from many
many vantage points against the worldwide flent testing network.

Those of you that have root access on your iphones can also test ecn
in this way.

A huge thanks to Christoph Paasch over at apple for pointing this out.

-- 
"For a successful technology, reality must take precedence over public
relations, for Mother Nature cannot be fooled" - Richard Feynman

dave@taht.net <Dave Täht> CTO, TekLibre, LLC Tel: 1-831-435-0729