telnet 协商

Telnet协议的一个特色是协商选项.Server和Client之间的选项由协商

产生,但也给协议带来了麻烦之处.简单的说,一个协商过程一般如下:

OC=Option Code

情况一:

Server:DO (OC)

Client:WILL (OC) 或 WON'T (OC)

服务器要求客户端打开OC选项,客户端同意或不同意.

情况二:

Server:DON'T (OC)

Client:WILL (OC) 或 WON'T (OC)

服务器要求客户端关闭OC选项,客户端同意或不同意.

这就是一般的Telnet协商选项的过程.

选项集定义如下:

EXTENDED-OPTIONS-LIST (EXOPL) 255 Extend Options RFC861

BINARY TRANSMIT 0 Begin Binary Transmit RFC856

ECHO 1 Request Echo RFC857

RCP 2 prepare to reconnect

SUPPRESS-GO-AHEAD 3 Suppress GA Command RFC858

NAMS 4 Approximate message size

STATUS 5 Get The Host Status RFC859

TIMING-MARK 6 For Ensure Transfer RFC860

RCTE 7 remote controlled transmission and echo

NAOL 8 negotiate about output line width

NAOP 9 negotiate about output page size

NAOCRD 10 negotiate about CR disposition

NAOHTS 11 negotiate about horizontal tabstops

NAOHTD 12 negotiate about horizontal tab disposition

NAOFFD 13 negotiate about formfeed disposition

NAOVTS 14 negotiate about vertical tab stops

NAOVTD 15 negotiate about vertical tab disposition

NAOLFD 16 negotiate about output LF disposition

XASCII 17 extended ascic character set

LOGOUT 18 force logout

BM 19 byte macro

DET 20 Data Entry Terminal RFC1043 Telnet DODIIS

SUPDUP 21 supdup protocol

SUPDUPOUTPUT 22 supdup output

SNDLOC 23 send location

TERMINAL-TYPE 24 Request Terminal Type RFC1091 Terminal

Type

pe in RFC1700 P129

END-OF-RECORD 25 Enable EOR Command RFC884

TUID 26 TACACS User Identification RFC927

OUTMRK 27 Output Marking RFC933

TTYLOC 28 Terminal Location Number RFC946

3270-REGIME 29 3270 Regime RFC1041

X3PAD 30 X.3 PAD RFC1053

NAWS 31 window size RFC1073

TSPEED 32 terminal speed RFC1079

LFLOW 33 remote flow control RFC1372

LINEMODE 34 Linemode option RFC1184

XDISPLOC 35 X-DISPLAY-LOCATION RFC1096

3270-REGIME 29 3270 Regime RFC1041

X3PAD 30 X.3 PAD RFC1053

NAWS 31 window size RFC1073

TSPEED 32 terminal speed RFC1079

LFLOW 33 remote flow control RFC1372

LINEMODE 34 Linemode option RFC1184

XDISPLOC 35 X-DISPLAY-LOCATION RFC1096

NEW-ENVIRON 39 New Environment Variable RFC1572

CHARSET 42 negotiate Charset RFC2066

SUBLIMINAL-MESSAGE 257 ????????????????? RFC1197