@url{https://en.wikipedia.org/wiki/XMODEM, XMODEM} does, causes
unacceptable performance degradation.
+Internally it uses various timeouts and deadlines. One of them used
+extensively is 10 seconds default deadline timeout. You can override it
+with @env{$NNCPDEADLINE} environment variable, that could be useful with
+very high delay links.
+
SP works on top of
@url{http://noiseprotocol.org/noise.html#interactive-patterns,
@code{Noise_IK_25519_ChaChaPoly_BLAKE2b}} protocol. Each Noise packet