.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
-.\" @(#)telnetd.8 8.4 (Berkeley) 6/1/94
+.\" @(#)telnetd.8 8.3 (Berkeley) 3/1/94
+.\" $FreeBSD: src/libexec/telnetd/telnetd.8,v 1.23 2001/07/15 07:53:42 dd Exp $
.\"
-.Dd June 1, 1994
+.Dd March 1, 1994
.Dt TELNETD 8
-.Os BSD 4.2
+.Os
.Sh NAME
.Nm telnetd
.Nd DARPA
protocol server
.Sh SYNOPSIS
.Nm /usr/libexec/telnetd
-.Op Fl BUhlkns
+.Op Fl Uhlkns
.Op Fl D Ar debugmode
.Op Fl I Ns Ar initid
.Op Fl S Ar tos
.Op Fl X Ar authtype
.Op Fl a Ar authmode
.Op Fl edebug
+.Op Fl p Ar loginprog
.Op Fl r Ns Ar lowpty-highpty
.Op Fl u Ar len
.Op Fl debug Op Ar port
.Sh DESCRIPTION
The
-.Nm telnetd
+.Nm
command is a server which supports the
.Tn DARPA
standard
The
.Fl debug
option may be used to start up
-.Nm telnetd
+.Nm
manually, instead of through
.Xr inetd 8 .
-If started up this way,
+If started up this way,
.Ar port
may be specified to run
-.Nm telnetd
+.Nm
on an alternate
.Tn TCP
port number.
.Pp
The
-.Nm telnetd
+.Nm
command accepts the following options:
-.Bl -tag -width "-a authmode"
+.Bl -tag -width indent
.It Fl a Ar authmode
This option may be used for specifying what mode should
be used for authentication.
Note that this option is only useful if
-.Nm telnetd
+.Nm
has been compiled with support for the
.Dv AUTHENTICATION
option.
There are several valid values for
-.Ar authmode:
+.Ar authmode :
.Bl -tag -width debug
-.It debug
-Turns on authentication debugging code.
-.It user
+.It Cm debug
+Turn on authentication debugging code.
+.It Cm user
Only allow connections when the remote user
can provide valid authentication information
to identify the remote user,
and is allowed access to the specified account
without providing a password.
-.It valid
+.It Cm valid
Only allow connections when the remote user
can provide valid authentication information
to identify the remote user.
command will provide any additional user verification
needed if the remote user is not allowed automatic
access to the specified account.
-.It other
+.It Cm other
Only allow connections that supply some authentication information.
This option is currently not supported
by any of the existing authentication mechanisms,
and is thus the same as specifying
.Fl a
.Cm valid .
-.It none
+.It Cm none
This is the default state.
Authentication information is not required.
If no or insufficient authentication information
.Xr login 1
program will provide the necessary user
verification.
-.It off
-This disables the authentication code.
+.It Cm off
+Disable the authentication code.
All user verification will happen through the
.Xr login 1
program.
.El
-.It Fl B
-Specifies bftp server mode. In this mode,
-.Nm telnetd
-causes login to start a
-.Xr bftp 1
-session rather than the user's
-normal shell. In bftp daemon mode normal
-logins are not supported, and it must be used
-on a port other than the normal
-.Tn TELNET
-port.
.It Fl D Ar debugmode
This option may be used for debugging purposes.
This allows
-.Nm telnetd
+.Nm
to print out debugging information
to the connection, allowing the user to see what
-.Nm telnetd
+.Nm
is doing.
-There are several possible values for
-.Ar debugmode:
+There are several possible values for
+.Ar debugmode :
.Bl -tag -width exercise
.It Cm options
-Prints information about the negotiation of
+Print information about the negotiation of
.Tn TELNET
options.
.It Cm report
-Prints the
+Print the
.Cm options
information, plus some additional information
about what processing is going on.
.It Cm netdata
-Displays the data stream received by
-.Nm telnetd.
+Display the data stream received by
+.Nm .
.It Cm ptydata
-Displays data written to the pty.
+Display data written to the pty.
.It Cm exercise
Has not been implemented yet.
.El
.It Fl debug
-Enables debugging on each socket created by
-.Nm telnetd
+Enable debugging on each socket created by
+.Nm
(see
.Dv SO_DEBUG
in
.Xr socket 2 ) .
.It Fl edebug
If
-.Nm telnetd
+.Nm
has been compiled with support for data encryption, then the
.Fl edebug
option may be used to enable encryption debugging code.
+.It Fl p Ar loginprog
+Specify an alternate
+.Xr login 1
+command to run to complete the login. The alternate command must
+understand the same command arguments as the standard login.
.It Fl h
-Disables the printing of host-specific information before
+Disable the printing of host-specific information before
login has been completed.
.It Fl I Ar initid
This option is only applicable to
to use when init starts login sessions. The default
.Dv ID
is
-.Dv fe.
+.Dv fe .
.It Fl k
This option is only useful if
-.Nm telnetd
+.Nm
has been compiled with both linemode and kludge linemode
support. If the
.Fl k
support the
.Dv LINEMODE
option, then
-.Nm telnetd
+.Nm
will operate in character at a time mode.
It will still support kludge linemode, but will only
go into kludge linemode if the remote client requests
it.
-(This is done by by the client sending
+(This is done by the client sending
.Dv DONT SUPPRESS-GO-AHEAD
and
.Dv DONT ECHO . )
(if they respond with
.Dv WILL TIMING-MARK
in response to a
-.Dv DO TIMING-MARK)
+.Dv DO TIMING-MARK )
for kludge linemode support.
.It Fl l
-Specifies line mode. Tries to force clients to use line-
+Specify line mode. Try to force clients to use line-
at-a-time mode.
If the
.Dv LINEMODE
Disable
.Dv TCP
keep-alives. Normally
-.Nm telnetd
+.Nm
enables the
.Tn TCP
keep-alive mechanism to probe connections that
be reached may be cleaned up.
.It Fl r Ar lowpty-highpty
This option is only enabled when
-.Nm telnetd
+.Nm
is compiled for
-.Dv UNICOS.
+.Dv UNICOS .
It specifies an inclusive range of pseudo-terminal devices to
use. If the system has sysconf variable
.Dv _SC_CRAY_NPTY
configured, the default pty search range is 0 to
-.Dv _SC_CRAY_NPTY;
+.Dv _SC_CRAY_NPTY ;
otherwise, the default range is 0 to 128. Either
.Ar lowpty
or
either end of the search range. If
.Ar lowpty
is omitted, the - character is still required so that
-.Nm telnetd
+.Nm
can differentiate
.Ar highpty
from
.Ar lowpty .
.It Fl s
This option is only enabled if
-.Nm telnetd
+.Nm
is compiled with support for
.Tn SecurID
cards.
should be put into the
.Pa utmp
file.
-.ne 1i
.It Fl U
This option causes
-.Nm telnetd
+.Nm
to refuse connections from addresses that
cannot be mapped back into a symbolic name
via the
routine.
.It Fl X Ar authtype
This option is only valid if
-.Nm telnetd
+.Nm
has been built with support for the authentication option.
It disables the use of
.Ar authtype
authentication, and
can be used to temporarily disable
a specific authentication type without having to recompile
-.Nm telnetd .
+.Nm .
.El
.Pp
.Nm Telnetd
operates by allocating a pseudo-terminal device (see
.Xr pty 4 )
for a client, then creating a login process which has
-the slave side of the pseudo-terminal as
+the slave side of the pseudo-terminal as
.Dv stdin ,
.Dv stdout
and
.Pp
When a
.Tn TELNET
-session is started up,
-.Nm telnetd
+session is started up,
+.Nm
sends
.Tn TELNET
options to the client side indicating
.Ed
.Pp
The pseudo-terminal allocated to the client is configured
-to operate in \*(lqcooked\*(rq mode, and with
+to operate in
+.Dq cooked
+mode, and with
.Dv XTABS and
.Dv CRMOD
enabled (see
When terminal echo is not desired, a
.Dv WILL ECHO
is sent to indicate that
-.Tn telnetd
+.Nm
will take care of echoing any data that needs to be
echoed to the terminal, and then nothing is echoed.
When terminal echo is desired, a
.Dv WONT ECHO
is sent to indicate that
-.Tn telnetd
+.Nm
will not be doing any terminal echoing, so the
client should do any terminal echoing that is needed.
.It "WILL BINARY"
-Indicates that the client is willing to send a
+Indicate that the client is willing to send a
8 bits of data, rather than the normal 7 bits
of the Network Virtual Terminal.
.It "WILL SGA"
-Indicates that it will not be sending
-.Dv IAC GA,
+Indicate that it will not be sending
+.Dv IAC GA ,
go ahead, commands.
.It "WILL STATUS"
-Indicates a willingness to send the client, upon
+Indicate a willingness to send the client, upon
request, of the current status of all
.Tn TELNET
options.
.Dv DO TIMING-MARK
command is received, it is always responded
to with a
-.Dv WILL TIMING-MARK
-.ne 1i
+.Dv WILL TIMING-MARK .
.It "WILL LOGOUT"
When a
.Dv DO LOGOUT
session is shut down.
.It "WILL ENCRYPT"
Only sent if
-.Nm telnetd
+.Nm
is compiled with support for data encryption, and
indicates a willingness to decrypt
the data stream.
.Bl -tag -width "DO AUTHENTICATION"
.It "DO BINARY"
Sent to indicate that
-.Tn telnetd
+.Nm
is willing to receive an 8 bit data stream.
.It "DO LFLOW"
Requests that the client handle flow control
This is not really supported, but is sent to identify a 4.2BSD
.Xr telnet 1
client, which will improperly respond with
-.Dv WILL ECHO.
+.Dv WILL ECHO .
If a
.Dv WILL ECHO
is received, a
.Dv DONT ECHO
will be sent in response.
.It "DO TERMINAL-TYPE"
-Indicates a desire to be able to request the
+Indicate a desire to be able to request the
name of the type of terminal that is attached
to the client side of the connection.
.It "DO SGA"
-Indicates that it does not need to receive
-.Dv IAC GA,
+Indicate that it does not need to receive
+.Dv IAC GA ,
the go ahead command.
.It "DO NAWS"
Requests that the client inform the server when
the window (display) size changes.
.It "DO TERMINAL-SPEED"
-Indicates a desire to be able to request information
+Indicate a desire to be able to request information
about the speed of the serial line to which
the client is attached.
.It "DO XDISPLOC"
-Indicates a desire to be able to request the name
-of the X windows display that is associated with
+Indicate a desire to be able to request the name
+of the X Window System display that is associated with
the telnet client.
.It "DO NEW-ENVIRON"
-Indicates a desire to be able to request environment
+Indicate a desire to be able to request environment
variable information, as described in RFC 1572.
.It "DO ENVIRON"
-Indicates a desire to be able to request environment
+Indicate a desire to be able to request environment
variable information, as described in RFC 1408.
.It "DO LINEMODE"
Only sent if
-.Nm telnetd
+.Nm
is compiled with support for linemode, and
requests that the client do line by line processing.
.It "DO TIMING-MARK"
Only sent if
-.Nm telnetd
+.Nm
is compiled with support for both linemode and
kludge linemode, and the client responded with
-.Dv WONT LINEMODE.
+.Dv WONT LINEMODE .
If the client responds with
-.Dv WILL TM,
+.Dv WILL TM ,
the it is assumed that the client supports
kludge linemode.
Note that the
option can be used to disable this.
.It "DO AUTHENTICATION"
Only sent if
-.Nm telnetd
+.Nm
is compiled with support for authentication, and
indicates a willingness to receive authentication
information for automatic login.
.It "DO ENCRYPT"
Only sent if
-.Nm telnetd
+.Nm
is compiled with support for data encryption, and
indicates a willingness to decrypt
the data stream.
-.Sh ENVIRONMENT
+.El
+.Sh NOTES
+By default
+.Nm
+will read the
+.Em \&he ,
+.Em \&hn ,
+and
+.Em \&im
+capabilities from
+.Pa /etc/gettytab
+and use that information (if present) to determine
+what to display before the login: prompt. You can
+also use a System V style
+.Pa /etc/issue
+file by using the
+.Em \&if
+capability, which will override
+.Em \&im .
+The information specified in either
+.Em \&im
+or
+.Em \&if
+will be displayed to both console and remote logins.
+.\" .Sh ENVIRONMENT
.Sh FILES
-.Pa /etc/services
-.br
-.Pa /etc/inittab
+.Bl -tag -width /usr/ucb/bftp -compact
+.It Pa /etc/services
+.It Pa /etc/gettytab
+.It Pa /etc/inittab
(UNICOS systems only)
-.br
-.Pa /etc/iptos
+.It Pa /etc/iptos
(if supported)
-.br
-.Pa /usr/ucb/bftp
+.It Pa /usr/ucb/bftp
(if supported)
+.El
.Sh "SEE ALSO"
-.Xr telnet 1 ,
+.Xr bftp 1 ,
.Xr login 1 ,
-.Xr bftp 1
+.Xr gettytab 5 ,
+.Xr telnet 1
(if supported)
.Sh STANDARDS
.Bl -tag -compact -width RFC-1572
Telnet Environment Option Interoperability Issues
.It Cm RFC-1572
Telnet Environment Option
+.El
.Sh BUGS
Some
.Tn TELNET
.Pp
Because of bugs in the original 4.2 BSD
.Xr telnet 1 ,
-.Nm telnetd
+.Nm
performs some dubious protocol exchanges to try to discover if the remote
client is, in fact, a 4.2 BSD
.Xr telnet 1 .
.Tn TELNET
.Dv IAC GA
(go ahead) commands.
+.Sh HISTORY
+IPv6 support was added by WIDE/KAME project.
projects / apple / network_cmds.git / blobdiff