📄 rfc726.txt
字号:
NWG/RFC# 726 JBP DHC 8-MAR-77 08:29 39237
Remote Controlled Transmission & Echoing Telnet Option
Network Working Group Jon Postel & Dave Crocker
Request for Comments: 726 SRI-ARC UC Irvine
NIC: 39237 8 March 1977
Remote Controlled Transmssion and Echoing Telnet Option
1
1. Command name and code: 2
RCTE 7 2a
2. Command meanings: 3
IAC WILL RCTE 3a
The sender of this command REQUESTS or AGREES to use
the RCTE option, and will send instructions for
controlling the other side's terminal printer. 3a1
IAC WON'T RCTE 3b
The sender of this option REFUSES to send instructions
for controlling the other side's terminal printer. 3b1
IAC DO RCTE 3c
The sender REQUEST or AGREES to have the other side
(sender of WILL RCTE) issue commands which will control
his (sender of the DO) output to the terminal printer. 3c1
IAC DON'T RCTE 3d
The sender of this command REFUSES to allow the other
side to control his (sender of DON'T) terminal printer. 3d1
IAC SB RCTE <cmd> [BC1 BC2] [TC1 TC2] IAC SE 3e
where: 3e1
<cmd> is one 8-bit byte having the following flags
(bits are counted from the right): 3e1a
[page 1]
NWG/RFC# 726 JBP DHC 8-MAR-77 08:29 39237
Remote Controlled Transmission & Echoing Telnet Option
Bit Meaning 3e1b
0 0 = Ignore all other bits in this byte and
repeat the last <cmd> that was sent. Equals
a 'continue what you have been doing'.
1 = Perform actions as indicated by other bits
in this byte. 3e1c
1 0 = Print (echo) break character
1 = Skip (don't echo) break character 3e1d
2 0 = Print (echo) text up to break character
1 = Skip (don't echo) text up to break character 3e1e
3 0 = Continue using same classes of break
characters.
1 = The two 8-bit bytes following this byte
contain flags for the new break classes. 3e1f
4 0 = Continue using same classes of transmit
characters.
1 = Reset transmit classes according to the two
bytes following 1) the break classes bytes,
if the break classes are also being reset,
or 2) this byte, if the break classes are
NOT also being reset. 3e1g
Value (decimal) of the <cmd> byte and its meaning: 3e1h
0 = Continue what you have been doing 3e1i
Even numbers greater than zero (i.e. numbers with the
right most bit off) are in error and should be
interpreted as equal to zero. When the <cmd> is an
even number greater than zero, classes bytes TC1 &
TC2 and/or BC1 & BC2 must not be sent. 3e1j
1 = Print (echo) up to AND INCLUDING break character 3e1k
3 = Print up to break character and SKIP (don't echo)
break character 3e1l
5 = Skip text (don't echo) up to break character, but
PRINT break character 3e1m
7 = Skip up to and including break character 3e1n
Add one of the previous non-zero values to one of the
following values, to get the total decimal value for
[page 2]
NWG/RFC# 726 JBP DHC 8-MAR-77 08:29 39237
Remote Controlled Transmission & Echoing Telnet Option
the byte (Note that classes may not be reset without
also resetting the printing action; so an odd number
is guaranteed): 3e1o
8 = Set break classes (using the next two bytes [BC1
BC2]) 3e1p
16 = Set transmission classes (using the next two
bytes [TC1 TC2]) 3e1q
24 = Set break classes (using the next two bytes [BC1
BC2]) and the transmission classes (using the two
bytes after that [TC1 TC2]). 3e1r
Sub-commands (IAC SB RCTE...) are only sent by the
controlling host and, in addition to other functions,
functionally replace the Go-Ahead (IAC GA) Telnet
feature. RCTE also functionally replaces the Echo (IAC
ECHO) Telnet option. That is the Suppress Go-Ahead
option should be in force and the Echo option should
not be in force while the RCTE option is in use. The
echo mode on terminating use of the RCTE option should
be the default state, that is DON'T ECHO, WON'T ECHO. 3e2
Classes for break and transmission (the right-most bit
of the second byte (TC2 or BC2) represents class 1; the
left-most bit of the first byte (TC1 or BC1) represents
the currently undefined class 16: 3e3
1: Upper-Case Letter (A-Z) 3e3a
2: Lower-case Letters (a-z) 3e3b
3: Numbers (0-9) 3e3c
4: Format Effectors (<BS> <CR> <LF> <FF> <HT> <VT>) 3e3d
The sequence <cr><lf> counts as one character when
processed as the Telnet end of line, and is a
single break character when class 4 is set. The
sequence <cr><nul> counts as one character and
is a break character if and only if <cr> is a
break character (i.e. class 4 is set).
5: Non-format Effector Control Characters including
<DEL> and <ESC> 3e3e
6: . , ; : ? ! 3e3f
[page 3]
NWG/RFC# 726 JBP DHC 8-MAR-77 08:29 39237
Remote Controlled Transmission & Echoing Telnet Option
7: { [ ( < > ) ] } 3e3g
8: ' " / \ % @ $ & # + - * = ^ _ | ~ 3e3h
9: <Space> 3e3i
And Telnet commands (IAC . . .) sent by the user are
always to have the effect of a break character. That
is, every instance of an IAC is to be treated as a
break character, except the sequence IAC IAC. 3e3j
The representation to be displayed when printing is
called for is the obvious one for the visible
characters (classes 1, 2, 3, 6, 7, and 8). Space (class
9) is represented by a blank space. The format
effectors (class 4) by their format effect. The
non-format effector controls (class 5) print nothing
(no space). 3e4
Initially no break classes or transmission classes are
in effect. 3e5
Please note that if all the bits are set in a Telnet
subcommand argument byte such as TC2 or BC2 then that
byte must be preceeded by an <IAC> flag byte. This is
the common convention of doubling the escape character
to use its value as data. 3e6
Sub-commands (IAC SB RCTE...) are refered to as "break
reset commands". 3e7
3. Default: 4
WON'T RCTE -- DON'T RCTE 4a
Neither host asserts special control over the other
host's terminal printer. 4a1
4. Motivation for the option: 5
RFC's 1, 5 and 51 discuss Network and process efficiency
and smoothness. 5a
RFC 357, by John Davidson, introduces the problem of
echoing delay that occurs when a remote user accesses a
full-duplex host, thru a satellite link. In order to save
the many thousands of miles of transit time for each
echoed character, while still permitting full server
responsiveness and clean terminal output, an echo control
[page 4]
NWG/RFC# 726 JBP DHC 8-MAR-77 08:29 39237
Remote Controlled Transmission & Echoing Telnet Option
similar to that used by some time-sharing systems is
suggested for the entire Network. 5b
In effect, the option described in this document
involves making a using host carefully regulate the
local terminal printer according to explicit
instructions from the remote (serving) host. 5b1
An important additional issue is efficient Network
transmission. Implementation of the Davidson Echoing
Scheme will eliminate almost all server-to-user echoing. 5c
The option described in this document also requests
using hosts to buffer a terminal's input to the serving
host until it forms a useful unit (with "useful unit"
delimited by break or transmission characters as
described below). Therefore, fewer messages are sent on
the user-to-server path. 5c1
N.B.: This option is only intended for use with
full-duplex hosts. The Go-Ahead Telnet feature is
completely adequate for half-duplex server hosts. Also,
RCTE should be used in place of the ECHO Telnet option.
That is the Suppress Go-Ahead option should be in force
and the Echo option should not be in force while the RCTE
option is in use. 5d
[page 5]
NWG/RFC# 726 JBP DHC 8-MAR-77 08:29 39237
Remote Controlled Transmission & Echoing Telnet Option
5. Explicit description of control mechanism: 6
User Terminal Printing Action & Control Procedure 6a
Negotiate the use of the RCTE option. Once the option
is in force the user Telnet follows the following
procedure. 6a1
1) Read an item from the network. 6a2
If the item is data, then print it and go to 1. 6a2a
If the item is a command, then set the classes and go
to 2. 6a2b
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -