conn_tcpip('open','server' [,PORT, PUBLICKEY])   : open TCP/IP port in local machine and waits for client to connect (default PORT=6111 KEY='')
                                                  If no PORT is entered, conn_tcpip will first attempt port 6111 and if that fails it will
                                                  bind instead to the first available port. 

conn_tcpip('open','client' [,IP, PORT, PRIVATEKEY]) : connect to server TCP/IP port at IP:PORT (default IP='127.0.0.1' PORT=6111 KEY='')
                                                  If a non-empty PUBLICKEY string was provided when opening the server, the server will reject 
                                                  any client connection where conn_tcpip('keypair',PRIVATEKEY) is different from PUBLICKEY
                                                  (note: use [PUBLICKEY,PRIVATEKEY]=conn_tcpip('keypair') to generate a one-time-use KEY pair)

conn_tcpip('write',VAR)                         : sends data (from server/client to client/server)
                                                  VAR may be any Matlab variable (numeric/string/cell/struct/etc.)
                                                  returns 1 if success, 0 if error

VAR = conn_tcpip('read')                        : receives data (from server/client to client/server)

conn_tcpip('writefromfile',FILENAME)            : sends raw data from file 
                                                  returns 1 if success, 0 if error

TIMESTAMP = conn_tcpip('readtofile',FILENAME)   : receives raw data and save it to file 
                                                  returns TIMESTAMP (conn_tcpip sethash timestamp) or MD5-hash (conn_tcpip sethash md5) of received data (empty if error)

conn_tcpip('close')                             : stops server/client
conn_tcpip('clear')                             : clears connection buffers

conn_tcpip('writekeepalive')                    : sends an empty/keepalive packet
conn_tcpip('sethash','md5')                     : uses MD5-hash to identify changes in files (slower)
conn_tcpip('sethash','timestamp')               : uses filesystem last-modified timestamps to identify changes in files (faster)
[publickey, privatekey] = conn_tcpip('keypair') : generates one-time-use public (used by server) & private (used by client) key pair
publickey = conn_tcpip('keypair', privatekey)   : generates public key (used by server) from user-defined private key (used by client)

  >> conn_tcpip open server
  Opening port 6111...
  Waiting for client connection...
  *************************************************************************************************************

  To connect to this server from a different machine, use the Matlab syntax:
     conn_tcpip open client alfonsosmbp2018.lan

  To connect to this server using ssh-tunneling, use the following syntax instead:
     $(OS-command)     :   ssh -L 6111:localhost:6111 alfnie@alfonsosmbp2018.lan
     >(Matlab-command) :   conn_tcpip open client 127.0.0.1 6111

  *************************************************************************************************************

  >> conn_tcpip open client alfonsosmbp2018.lan
  Connecting to alfonsosmbp2018.lan:6111...
  Succesfully established connection to server

  >> conn_tcpip('write', rand(1,10));

  >> disp(conn_tcpip('read'));
  0.3902    0.8448    0.3720    0.7076    0.3457    0.8772    0.7505    0.4344    0.4007    0.3729

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