Magic Wormhole: get things from one computer to another, safely

Re:Magic Wormhole: get things from one computer to another, ... by sleepydog on Sunday August 18, 2024 @03:01PM (#41284508)

As a protocol tcp should be able to utilize a long fat pipe with a large enough receive window. You might want to check what window scaling factor is used and look for a tunable. I accept that some implementations may have limits beyond the protocol level. And even low levels of packet loss can severely affect throughput of a single stream.

A bigger reason you want multiple streams is because most network providers use a stream identifier like the 5-tuple hash to spread traffic, and support single-stream bandwidth much lower than whatever aggregate they may advertise.

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Re:Magic Wormhole: get things from one computer to another, ... by bscphil on Sunday August 18, 2024 @04:32PM (#41285258)

> with a large enough receive window

Yeah, that's the issue. I didn't have root permissions on either side. Moreover, a transfer tool should just work without requiring its users to have expert knowledge like this.

In this case, I checked the roundtrip ping time and multiplied it by the buffer size, and it agreed with the speeds I was seeing within ~5%, so it was not an issue with throttling. Actually, if I were a network provider interested in doing this, I would throttle on the 2-tuple as well.

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