When the Binary option has been successfully negotiated, arbitrary 8-bit characters are allowed. However, the data stream MUST still be scanned for IAC characters, any embedded Telnet commands MUST be obeyed, and data bytes equal to IAC MUST be doubled. Other character processing (e.g., replacing CR by CR NUL or by CR LF) MUST NOT be done. In particular, there is no end-of-line convention (see Section 3.3.1) in binary mode.
The Binary option is normally negotiated in both directions, to change the Telnet connection from NVT mode to "binary mode".
The sequence IAC EOR can be used to delimit blocks of data within a binary-mode Telnet stream.