Hi, I wrote a small dtrace script to track ECN connections on MacOS.
It basically dumps the ecn_flags from the MacOS kernel to find out if ECN was successfully negotiated or not. It further counts ECN bits on incoming packets. For anyone interested (feel free to share), the code is here: https://github.com/janrueth/macos-passive-ecn-sniffer During testing I also observed a weird behavior (connections fail) between MacOS and Linux when ECN flags cause packet drops on the downlink (reverse) path. There is also a more detailed description and a packet trace of this happening in the github repository. If you have any comments, feel free to contact me. Best Jan On 9. Mar 2021, at 21:38, Dave Taht <dave.t...@gmail.com<mailto:dave.t...@gmail.com>> wrote: 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 d...@taht.net <Dave Täht> CTO, TekLibre, LLC Tel: 1-831-435-0729 _______________________________________________ Ecn-sane mailing list ecn-s...@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/ecn-sane
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