Summery
指定したTCPポートでリモートサーバーにアクセスする。
Construction
$ telnet [IP or Domain] [port]
Option
-4:
-6:
-8: 8bitのデータ入力許可
-a: 自動ログイン
-l %user: ログインユーザーの指定
port: Default:23
Sample
# 192.168.1.1サーバーへログイン
$ telnet 192.168.1.1
※メール対話のやり方は以下のURLを参照
http://ash.jp/net/telnet_smtp.htm
Discription
NAME
telnet -- user interface to the TELNET protocol
SYNOPSIS
telnet [-468EFKLNacdfruxy] [-S tos] [-X authtype] [-e escapechar] [-k realm]
[-l user] [-n tracefile] [-s src_addr] [host [port]]
DESCRIPTION
The telnet command is used to communicate with another host using the TELNET
protocol. If telnet is invoked without the host argument, it enters command
mode, indicated by its prompt (``telnet>''). In this mode, it accepts and
executes the commands listed below. If it is invoked with arguments, it per-
forms an open command with those arguments.
Options:
-4 Forces telnet to use IPv4 addresses only.
-6 Forces telnet to use IPv6 addresses only.
-8 Specifies an 8-bit data path. This causes an attempt to negotiate the
TELNET BINARY option on both input and output.
-E Stops any character from being recognized as an escape character.
-F If Kerberos V5 authentication is being used, the -F option allows the
local credentials to be forwarded to the remote system, including any
credentials that have already been forwarded into the local environ-
ment.
-K Specifies no automatic login to the remote system.
-L Specifies an 8-bit data path on output. This causes the BINARY option
to be negotiated on output.
-N Prevents IP address to name lookup when destination host is given as
an IP address.
-S tos Sets the IP type-of-service (TOS) option for the telnet connection to
the value tos, which can be a numeric TOS value or, on systems that
support it, a symbolic TOS name found in the /etc/iptos file.
-X atype
Disables the atype type of authentication.
-a Attempt automatic login. This is now the default, so this option is
ignored. Currently, this sends the user name via the USER variable of
the ENVIRON option if supported by the remote system. The name used
is that of the current user as returned by getlogin(2) if it agrees
with the current user ID, otherwise it is the name associated with the
user ID.
-c Disables the reading of the user's .telnetrc file. (See the toggle
skiprc command on this man page.)
-d Sets the initial value of the debug toggle to TRUE.
-e escapechar
Sets the initial telnet escape character to escapechar. If escapechar
is omitted, then there will be no escape character.
-f If Kerberos V5 authentication is being used, the -f option allows the
local credentials to be forwarded to the remote system.
-k realm
If Kerberos authentication is being used, the -k option requests that
telnet obtain tickets for the remote host in realm realm instead of
the remote host's realm, as determined by krb_realmofhost(3).
-l user
When connecting to the remote system, if the remote system understands
the ENVIRON option, then user will be sent to the remote system as the
value for the variable USER. This option implies the -a option. This
option may also be used with the open command.
-n tracefile
Opens tracefile for recording trace information. See the set
tracefile command below.
-r Specifies a user interface similar to rlogin(1). In this mode, the
escape character is set to the tilde (~) character, unless modified by
the -e option.
-s src_addr
Set the source IP address for the telnet connection to src_addr, which
can be an IP address or a host name.
-u Forces telnet to use AF_UNIX addresses only (e.g., UNIX domain sock-
ets, accessed with a file path).
-x Turns on encryption of the data stream if possible. This is now the
default, so this option is ignored.
-y Suppresses encryption of the data stream.
host Indicates the official name, an alias, or the Internet address of a
remote host. If host starts with a `/', telnet establishes a connec-
tion to the corresponding named socket.
port Indicates a port number (address of an application). If a number is
not specified, the default telnet port is used.
When in rlogin mode, a line of the form ~. disconnects from the remote host;
~ is the telnet escape character. Similarly, the line ~^Z suspends the telnet
session. The line ~^] escapes to the normal telnet escape prompt.
Once a connection has been opened, telnet will attempt to enable the TELNET
LINEMODE option. If this fails, then telnet will revert to one of two input
modes: either ``character at a time'' or ``old line by line'' depending on
what the remote system supports.
When LINEMODE is enabled, character processing is done on the local system,
under the control of the remote system. When input editing or character echo-
ing is to be disabled, the remote system will relay that information. The
remote system will also relay changes to any special characters that happen on
the remote system, so that they can take effect on the local system.
In ``character at a time'' mode, most text typed is immediately sent to the
remote host for processing.
In ``old line by line'' mode, all text is echoed locally, and (normally) only
completed lines are sent to the remote host. The ``local echo character''
(initially ``^E'') may be used to turn off and on the local echo (this would
mostly be used to enter passwords without the password being echoed).
If the LINEMODE option is enabled, or if the localchars toggle is TRUE (the
default for ``old line by line''; see below), the user's quit, intr, and flush
characters are trapped locally, and sent as TELNET protocol sequences to the
remote side. If LINEMODE has ever been enabled, then the user's susp and eof
are also sent as TELNET protocol sequences, and quit is sent as a TELNET ABORT
instead of BREAK. There are options (see toggle autoflush and toggle
autosynch below) which cause this action to flush subsequent output to the
terminal (until the remote host acknowledges the TELNET sequence) and flush
previous terminal input (in the case of quit and intr).
While connected to a remote host, telnet command mode may be entered by typing
the telnet ``escape character'' (initially ``^]''). When in command mode, the
normal terminal editing conventions are available.
The following telnet commands are available. Only enough of each command to
uniquely identify it need be typed (this is also true for arguments to the
mode, set, toggle, unset, slc, environ, and display commands).
auth argument ...
The auth command manipulates the information sent through the
TELNET AUTHENTICATE option. Valid arguments for the auth command
are:
disable type Disables the specified type of authentication. To
obtain a list of available types, use the auth
disable ? command.
enable type Enables the specified type of authentication. To
obtain a list of available types, use the auth enable
? command.
status Lists the current status of the various types of
authentication.
close Close a TELNET session and return to command mode.
display argument ...
Displays all, or some, of the set and toggle values (see below).
encrypt argument ...
The encrypt command manipulates the information sent through the
TELNET ENCRYPT option.
Valid arguments for the encrypt command are:
disable type [input | output]
Disables the specified type of encryption. If you
omit the input and output, both input and output are
disabled. To obtain a list of available types, use
the encrypt disable ? command.
enable type [input | output]
Enables the specified type of encryption. If you
omit input and output, both input and output are
enabled. To obtain a list of available types, use
the encrypt enable ? command.
input This is the same as the encrypt start input command.
-input This is the same as the encrypt stop input command.
output This is the same as the encrypt start output command.
-output This is the same as the encrypt stop output command.
start [input | output]
Attempts to start encryption. If you omit input and
output, both input and output are enabled. To obtain
a list of available types, use the encrypt enable ?
command.
status Lists the current status of encryption.
stop [input | output]
Stops encryption. If you omit input and output,
encryption is on both input and output.
type type Sets the default type of encryption to be used with
later encrypt start or encrypt stop commands.
environ arguments ...
The environ command is used to manipulate the variables that may be
sent through the TELNET ENVIRON option. The initial set of vari-
ables is populated with the contents of the following environment
variables, if present: USER, PRINTER, DISPLAY, TERM, COLUMNS,
LINES. Only the first three are exported, by default.
Valid arguments for the environ command are:
define variable [value]
Define the variable variable to have a value of value.
If value is empty, the value is taken from the environ-
ment variable. Any variables defined by this command
are automatically exported. The value may be enclosed
in single or double quotes so that tabs and spaces may
be included.
undefine variable
Remove variable from the list of environment variables.
export variable
Mark the variable variable to be exported to the remote
side.
unexport variable
Mark the variable variable to not be exported unless
explicitly asked for by the remote side.
list List the current set of environment variables. Those
marked with a * will be sent automatically, other vari-
ables will only be sent if explicitly requested.
? Prints out help information for the environ command.
logout Sends the TELNET LOGOUT option to the remote side. This command is
similar to a close command; however, if the remote side does not
support the LOGOUT option, nothing happens. If, however, the
remote side does support the LOGOUT option, this command should
cause the remote side to close the TELNET connection. If the
remote side also supports the concept of suspending a user's ses-
sion for later reattachment, the logout argument indicates that you
should terminate the session immediately.
mode type Type is one of several options, depending on the state of the
TELNET session. The remote host is asked for permission to go into
the requested mode. If the remote host is capable of entering that
mode, the requested mode will be entered.
character Disable the TELNET LINEMODE option, or, if the remote
side does not understand the LINEMODE option, then
enter ``character at a time'' mode.
line Enable the TELNET LINEMODE option, or, if the remote
side does not understand the LINEMODE option, then
attempt to enter ``old-line-by-line'' mode.
isig (-isig) Attempt to enable (disable) the TRAPSIG mode of the
LINEMODE option. This requires that the LINEMODE
option be enabled.
edit (-edit) Attempt to enable (disable) the EDIT mode of the
LINEMODE option. This requires that the LINEMODE
option be enabled.
softtabs (-softtabs)
Attempt to enable (disable) the SOFT_TAB mode of the
LINEMODE option. This requires that the LINEMODE
option be enabled.
litecho (-litecho)
Attempt to enable (disable) the LIT_ECHO mode of the
LINEMODE option. This requires that the LINEMODE
option be enabled.
? Prints out help information for the mode command.
open host [-l user] [[-]port]
Open a connection to the named host. If no port number is speci-
fied, telnet will attempt to contact a TELNET server at the default
port. The host specification may be either a host name (see
hosts(5)), an Internet address specified in the ``dot notation''
(see inet(3)), or IPv6 host name or IPv6 coloned-hexadecimal
addreess. The -l option may be used to specify the user name to be
passed to the remote system via the ENVIRON option. When connect-
ing to a non-standard port, telnet omits any automatic initiation
of TELNET options. When the port number is preceded by a minus
sign, the initial option negotiation is done. After establishing a
connection, the file .telnetrc in the users home directory is
opened. Lines beginning with a # are comment lines. Blank lines
are ignored. Lines that begin without white space are the start of
a machine entry. The first thing on the line is the name of the
machine that is being connected to. The rest of the line, and suc-
cessive lines that begin with white space are assumed to be telnet
commands and are processed as if they had been typed in manually to
the telnet command prompt.
quit Close any open TELNET session and exit telnet. An end of file (in
command mode) will also close a session and exit.
send arguments
Sends one or more special character sequences to the remote host.
The following are the arguments which may be specified (more than
one argument may be specified at a time):
abort Sends the TELNET ABORT (Abort processes) sequence.
ao Sends the TELNET AO (Abort Output) sequence, which should
cause the remote system to flush all output from the remote
system to the user's terminal.
ayt Sends the TELNET AYT (Are You There) sequence, to which the
remote system may or may not choose to respond.
brk Sends the TELNET BRK (Break) sequence, which may have sig-
nificance to the remote system.
ec Sends the TELNET EC (Erase Character) sequence, which
should cause the remote system to erase the last character
entered.
el Sends the TELNET EL (Erase Line) sequence, which should
cause the remote system to erase the line currently being
entered.
eof Sends the TELNET EOF (End Of File) sequence.
eor Sends the TELNET EOR (End of Record) sequence.
escape Sends the current telnet escape character (initially
``^'').
ga Sends the TELNET GA (Go Ahead) sequence, which likely has
no significance to the remote system.
getstatus
If the remote side supports the TELNET STATUS command,
getstatus will send the subnegotiation to request that the
server send its current option status.
ip Sends the TELNET IP (Interrupt Process) sequence, which
should cause the remote system to abort the currently run-
ning process.
nop Sends the TELNET NOP (No OPeration) sequence.
susp Sends the TELNET SUSP (SUSPend process) sequence.
synch Sends the TELNET SYNCH sequence. This sequence causes the
remote system to discard all previously typed (but not yet
read) input. This sequence is sent as TCP urgent data (and
may not work if the remote system is a 4.2BSD system -- if
it doesn't work, a lower case ``r'' may be echoed on the
terminal).
do cmd
dont cmd
will cmd
wont cmd
Sends the TELNET DO cmd sequence. Cmd can be either a dec-
imal number between 0 and 255, or a symbolic name for a
specific TELNET command. Cmd can also be either help or ?
to print out help information, including a list of known
symbolic names.
? Prints out help information for the send command.
set argument value
unset argument value
The set command will set any one of a number of telnet variables to
a specific value or to TRUE. The special value off turns off the
function associated with the variable, this is equivalent to using
the unset command. The unset command will disable or set to FALSE
any of the specified functions. The values of variables may be
interrogated with the display command. The variables which may be
set or unset, but not toggled, are listed here. In addition, any
of the variables for the toggle command may be explicitly set or
unset using the set and unset commands.
ayt If TELNET is in localchars mode, or LINEMODE is enabled,
and the status character is typed, a TELNET AYT sequence
(see send ayt preceding) is sent to the remote host. The
initial value for the ``Are You There'' character is the
terminal's status character.
echo This is the value (initially ``^E'') which, when in ``line
by line'' mode, toggles between doing local echoing of
entered characters (for normal processing), and suppressing
echoing of entered characters (for entering, say, a pass-
word).
eof If telnet is operating in LINEMODE or ``old line by line''
mode, entering this character as the first character on a
line will cause this character to be sent to the remote
system. The initial value of the eof character is taken to
be the terminal's eof character.
erase If telnet is in localchars mode (see toggle localchars
below), and if telnet is operating in ``character at a
time'' mode, then when this character is typed, a TELNET EC
sequence (see send ec above) is sent to the remote system.
The initial value for the erase character is taken to be
the terminal's erase character.
escape This is the telnet escape character (initially ``^['')
which causes entry into telnet command mode (when connected
to a remote system).
flushoutput
If telnet is in localchars mode (see toggle localchars
below) and the flushoutput character is typed, a TELNET AO
sequence (see send ao above) is sent to the remote host.
The initial value for the flush character is taken to be
the terminal's flush character.
forw1
forw2 If telnet is operating in LINEMODE, these are the charac-
ters that, when typed, cause partial lines to be forwarded
to the remote system. The initial value for the forwarding
characters are taken from the terminal's eol and eol2 char-
acters.
interrupt
If telnet is in localchars mode (see toggle localchars
below) and the interrupt character is typed, a TELNET IP
sequence (see send ip above) is sent to the remote host.
The initial value for the interrupt character is taken to
be the terminal's intr character.
kill If telnet is in localchars mode (see toggle localchars
below), and if telnet is operating in ``character at a
time'' mode, then when this character is typed, a TELNET EL
sequence (see send el above) is sent to the remote system.
The initial value for the kill character is taken to be the
terminal's kill character.
lnext If telnet is operating in LINEMODE or ``old line by line''
mode, then this character is taken to be the terminal's
lnext character. The initial value for the lnext character
is taken to be the terminal's lnext character.
quit If telnet is in localchars mode (see toggle localchars
below) and the quit character is typed, a TELNET BRK
sequence (see send brk above) is sent to the remote host.
The initial value for the quit character is taken to be the
terminal's quit character.
reprint
If telnet is operating in LINEMODE or ``old line by line''
mode, then this character is taken to be the terminal's
reprint character. The initial value for the reprint char-
acter is taken to be the terminal's reprint character.
rlogin This is the rlogin escape character. If set, the normal
telnet escape character is ignored unless it is preceded by
this character at the beginning of a line. This character,
at the beginning of a line followed by a "." closes the
connection; when followed by a ^Z it suspends the telnet
command. The initial state is to disable the rlogin escape
character.
start If the TELNET TOGGLE-FLOW-CONTROL option has been enabled,
then this character is taken to be the terminal's start
character. The initial value for the start character is
taken to be the terminal's start character.
stop If the TELNET TOGGLE-FLOW-CONTROL option has been enabled,
then this character is taken to be the terminal's stop
character. The initial value for the stop character is
taken to be the terminal's stop character.
susp If telnet is in localchars mode, or LINEMODE is enabled,
and the suspend character is typed, a TELNET SUSP sequence
(see send susp above) is sent to the remote host. The ini-
tial value for the suspend character is taken to be the
terminal's suspend character.
tracefile
This is the file to which the output, caused by netdata or
option tracing being TRUE, will be written. If it is set
to ``-'', then tracing information will be written to stan-
dard output (the default).
worderase
If telnet is operating in LINEMODE or ``old line by line''
mode, then this character is taken to be the terminal's
worderase character. The initial value for the worderase
character is taken to be the terminal's worderase charac-
ter.
? Displays the legal set (unset) commands.
opie sequence challenge
The opie command computes a response to the OPIE challenge.
slc state The slc command (Set Local Characters) is used to set or change the
state of the special characters when the TELNET LINEMODE option has
been enabled. Special characters are characters that get mapped to
TELNET commands sequences (like ip or quit) or line editing charac-
ters (like erase and kill). By default, the local special charac-
ters are exported.
check Verify the current settings for the current special
characters. The remote side is requested to send all
the current special character settings, and if there
are any discrepancies with the local side, the local
side will switch to the remote value.
export Switch to the local defaults for the special charac-
ters. The local default characters are those of the
local terminal at the time when telnet was started.
import Switch to the remote defaults for the special charac-
ters. The remote default characters are those of the
remote system at the time when the TELNET connection
was established.
? Prints out help information for the slc command.
status Show the current status of telnet. This includes the peer one is
connected to, as well as the current mode.
toggle arguments ...
Toggle (between TRUE and FALSE) various flags that control how
telnet responds to events. These flags may be set explicitly to
TRUE or FALSE using the set and unset commands listed above. More
than one argument may be specified. The state of these flags may
be interrogated with the display command. Valid arguments are:
authdebug Turns on debugging information for the authentication
code.
autoflush If autoflush and localchars are both TRUE, then when
the ao, or quit characters are recognized (and trans-
formed into TELNET sequences; see set above for
details), telnet refuses to display any data on the
user's terminal until the remote system acknowledges
(via a TELNET TIMING MARK option) that it has pro-
cessed those TELNET sequences. The initial value for
this toggle is TRUE if the terminal user had not done
an "stty noflsh", otherwise FALSE (see stty(1)).
autodecrypt When the TELNET ENCRYPT option is negotiated, by
default the actual encryption (decryption) of the
data stream does not start automatically. The
autoencrypt (autodecrypt) command states that encryp-
tion of the output (input) stream should be enabled
as soon as possible.
autologin If the remote side supports the TELNET AUTHENTICATION
option telnet attempts to use it to perform automatic
authentication. If the AUTHENTICATION option is not
supported, the user's login name are propagated
through the TELNET ENVIRON option. This command is
the same as specifying -a option on the open command.
autosynch If autosynch and localchars are both TRUE, then when
either the intr or quit characters is typed (see set
above for descriptions of the intr and quit charac-
ters), the resulting TELNET sequence sent is followed
by the TELNET SYNCH sequence. This procedure should
cause the remote system to begin throwing away all
previously typed input until both of the TELNET
sequences have been read and acted upon. The initial
value of this toggle is FALSE.
binary Enable or disable the TELNET BINARY option on both
input and output.
inbinary Enable or disable the TELNET BINARY option on input.
outbinary Enable or disable the TELNET BINARY option on output.
crlf If this is TRUE, then carriage returns will be sent
as <cr><lf>. If this is FALSE, then carriage returns
will be send as <cr><nul>. The initial value for
this toggle is FALSE.
crmod Toggle carriage return mode. When this mode is
enabled, most carriage return characters received
from the remote host will be mapped into a carriage
return followed by a line feed. This mode does not
affect those characters typed by the user, only those
received from the remote host. This mode is not very
useful unless the remote host only sends carriage
return, but never line feed. The initial value for
this toggle is FALSE.
debug Toggles socket level debugging (useful only to the
super user). The initial value for this toggle is
FALSE.
encdebug Turns on debugging information for the encryption
code.
localchars If this is TRUE, then the flush, interrupt, quit,
erase, and kill characters (see set above) are recog-
nized locally, and transformed into (hopefully)
appropriate TELNET control sequences (respectively
ao, ip, brk, ec, and el; see send above). The ini-
tial value for this toggle is TRUE in ``old line by
line'' mode, and FALSE in ``character at a time''
mode. When the LINEMODE option is enabled, the value
of localchars is ignored, and assumed to always be
TRUE. If LINEMODE has ever been enabled, then quit
is sent as abort, and eof and suspend are sent as eof
and susp (see send above).
netdata Toggles the display of all network data (in hexadeci-
mal format). The initial value for this toggle is
FALSE.
options Toggles the display of some internal telnet protocol
processing (having to do with TELNET options). The
initial value for this toggle is FALSE.
prettydump When the netdata toggle is enabled, if prettydump is
enabled the output from the netdata command will be
formatted in a more user readable format. Spaces are
put between each character in the output, and the
beginning of any telnet escape sequence is preceded
by a '*' to aid in locating them.
skiprc When the skiprc toggle is TRUE, telnet skips the
reading of the .telnetrc file in the users home
directory when connections are opened. The initial
value for this toggle is FALSE.
termdata Toggles the display of all terminal data (in hexadec-
imal format). The initial value for this toggle is
FALSE.
verbose_encrypt
When the verbose_encrypt toggle is TRUE, telnet
prints out a message each time encryption is enabled
or disabled. The initial value for this toggle is
FALSE.
? Displays the legal toggle commands.
z Suspend telnet. This command only works when the user is using the
csh(1).
! [command]
Execute a single command in a subshell on the local system. If
command is omitted, then an interactive subshell is invoked.
? [command]
Get help. With no arguments, telnet prints a help summary. If
command is specified, telnet will print the help information for
just that command.
ENVIRONMENT
telnet uses at least the HOME, SHELL, DISPLAY, and TERM environment variables.
Other environment variables may be propagated to the other side via the TELNET
ENVIRON option.
SEE ALSO
rlogin(1), rsh(1), hosts(5), nologin(5), telnetd(8)
FILES
~/.telnetrc user customized telnet startup values
HISTORY
The telnet command appeared in 4.2BSD.
IPv6 support was added by WIDE/KAME project.
NOTES
On some remote systems, echo has to be turned off manually when in ``old line
by line'' mode.
In ``old line by line'' mode or LINEMODE the terminal's eof character is only
recognized (and sent to the remote system) when it is the first character on a
line.
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