+-------------------+       +-----------------+
(Socket)InputStream ---> |  secsh transport  | <===> |  secsh channel  |
(Socket)OutputStream --> |  (auth, pipe)     |   N   |  (buffer)       |
                         +-------------------+       +-----------------+
                          @  feeder thread             | |
                             - read InputStream        | +-> InputStream
                             - feed into channel       +---> OutputStream
                               buffers

SIS <-- @ --> (parse, find chan) --> secsh chan: buffer <-- SSHInputStream
SSHOutputStream --> secsh chan --> secsh transport --> SOS   [no thread]