RFC 856 (rfc856) - Page 1 of 4


Telnet Binary Transmission



Alternative Format: Original Text Document



Network Working Group                                          J. Postel
Request for Comments: 856                                    J. Reynolds
                                                                     ISI
Obsoletes: NIC 15389                                            May 1983

                       TELNET BINARY TRANSMISSION


This RFC specifies a standard for the ARPA Internet community.  Hosts on
the ARPA Internet are expected to adopt and implement this standard.

1.  Command Name and Code

   TRANSMIT-BINARY      0

2.  Command Meanings

   IAC WILL TRANSMIT-BINARY

      The sender of this command REQUESTS permission to begin
      transmitting, or confirms that it will now begin transmitting
      characters which are to be interpreted as 8 bits of binary data by
      the receiver of the data.

   IAC WON'T TRANSMIT-BINARY

      If the connection is already being operated in binary transmission
      mode, the sender of this command DEMANDS to begin transmitting
      data characters which are to be interpreted as standard NVT ASCII
      characters by the receiver of the data.  If the connection is not
      already being operated in binary transmission mode, the sender of
      this command REFUSES to begin transmitting characters which are to
      be interpreted as binary characters by the receiver of the data
      (i.e., the sender of the data demands to continue transmitting
      characters in its present mode).

      A connection is being operated in binary transmission mode only
      when one party has requested it and the other has acknowledged it.

   IAC DO TRANSMIT-BINARY

      The sender of this command REQUESTS that the sender of the data
      start transmitting, or confirms that the sender of data is
      expected to transmit, characters which are to be interpreted as 8
      bits of binary data (i.e., by the party sending this command).

   IAC DON'T TRANSMIT-BINARY

      If the connection is already being operated in binary transmission
      mode, the sender of this command DEMANDS that the sender of the
      data start transmitting characters which are to be interpreted as


Postel & Reynolds