RE: Re: About remote login

NAME


     getty - set terminal type, modes, speed, and line discipline



SYNOPSIS


     /sbin/getty [-hN] [-t timeout] line [speed [type [linedisc]]]
     /sbin/getty -c file



DESCRIPTION


     getty is a program that is invoked by
<http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?init+1> init(1M).  It is
the second process
     in the series, (init-getty-login-shell) that ultimately connects a
user
     with the UNIX system.  It can only be executed by the super-user;
that
     is, a process with the user-ID of root.  Initially getty prints the
     contents of /etc/issue (if it exists), then prints the login
message
     field for the entry it is using from /etc/gettydefs, reads the
user's
     login name, and invokes the
<http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?login+1> login(1) command
with the user's name as
     argument. While reading the name, getty attempts to adapt the
system to
     the speed and type of terminal being used. It does this by using
the
     options and arguments specified.

     Line is the name of a tty line in /dev to which getty is to attach
     itself.  getty uses this string as the name of a file in the /dev
     directory to open for reading and writing. Unless getty is invoked
with
     the -h flag, getty will force a hangup on the line by setting the
speed
     to zero before setting the speed to the default or specified speed.
The
     -t flag plus timeout (in seconds), specifies that getty should exit
if
     the open on the line succeeds and no one types anything in the
specified
     number of seconds.

     The -N option honors the /etc/nologin file.  When present, getty
does not
     answer the line, but instead waits for the file to go away.

     Speed, the optional second argument, is a label to a speed and tty
     definition in the file /etc/gettydefs.  This definition tells getty
at
     what speed to initially run, what the login message should look
like,
     what the initial tty settings are, and what speed to try next
should the
     user indicate that the speed is inappropriate (by typing a <break>
     character).

     Type, the optional third argument, is a character string describing
to
     getty what type of terminal is connected to the line in question.
getty
     recognizes the following types:

  none default
  ds40-1 Dataspeed40/1
  tektronix,tek Tektronix
  vt61 DEC vt61
  vt100 DEC vt100
  hp45 Hewlett-Packard 45
  c100 Concept 100






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GETTY(1M) <http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?GETTY+1>
GETTY(1M) <http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?GETTY+1> 



     The default terminal is none; i.e., any crt or normal terminal
unknown to
     the system.  Also, for terminal type to have any meaning, the
virtual
     terminal handlers must be compiled into the operating system.  They
are
     available, but not compiled in the default condition.

     Linedisc, the optional fourth argument, is a character string
describing
     which line discipline to use in communicating with the terminal.
There
     are two line disciplines. LDISC0 is the familiar System V line
     discipline.  LDISC1 is similar to the 4.3BSD ``new tty driver''
(see
      <http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?termio+7> termio(7)).
LDISC1 is the default.

     When given no optional arguments, getty sets the speed of the
interface
     to 9600 baud, specifies that raw mode is to be used (awaken on
every
     character), that echo is to be suppressed, either parity allowed,
new-
     line characters will be converted to carriage return-line feed, and
tab
     expansion performed on the standard output.  It types the login
message
     before reading the user's name a character at a time.  If a null
     character (or framing error) is received, it is assumed to be the
result
     of the user pushing the ``break'' key.  This will cause getty to
attempt
     the next speed in the series.  The series that getty tries is
determined
     by what it finds in /etc/gettydefs.  Modems which "lock" to a
single
     speed, such as most high speed modems, should be used with a
gettydefs
     entry which sticks to a single speed, such as dx_19200.  This also
     applies to devices that send spurious ``break'' signals.  To allow
baud
     rate cycling on the main serial console, change the ttyd1 entry
from
     console to co_9600.

     After the user's name has been typed in, it is terminated by a
new-line
     or carriage-return character.  The latter results in the system
being set
     to treat carriage returns appropriately (see
<http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?ioctl+2> ioctl(2)).

     The user's name is scanned to see if it contains any lower-case
     alphabetic characters; if not, and if the name is non-empty, the
system
     is told to map any future upper-case characters into the
corresponding
     lower-case characters.

     Finally, login is exec(2)'d with the user's name as an argument.
     Additional arguments may be typed after the login name.  These are
passed
     to login, which will place them in the environment (see
<http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?login+1> login(1)).

     If getty is running on the graphics console, getty checks to see if
     autologin is enabled by verifying the existence of /etc/autologin
and
     /etc/autologin.on (see
<http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?login+1> login(1)). If
autologin is enabled, getty will
     invoke login with the autologin option.

     getty cannot be used on a line that is also to be used by outgoing
calls
     made by uucp, cu, or similar programs.  The very similar
<http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?uugetty+1> uugetty(1M) use
     should be used instead.

     When getty is invoked with the -c option and file, it scans the
file as
     if it were scanning /etc/gettydefs during normal operation, and
prints
     out the results to the standard output.  If there are any
unrecognized



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GETTY(1M) <http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?GETTY+1>
GETTY(1M) <http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?GETTY+1> 



     modes or improperly constructed entries, it reports these. If the
     entries are correct, it prints out the values of the various flags.
See
      <http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?ioctl+2> ioctl(2) to
interpret the values. Note that some values are added to the
     flags automatically.



FILES


     /etc/nologin
     /etc/gettydefs
     /etc/issue     message printed before login prompt
     /etc/autologin
     /etc/autologin.on
     /var/adm/SYSLOG



SEE ALSO


     init(1M) <http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?init+1> ,
login(1) <http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?login+1> ,
uugetty(1M) <http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?uugetty+1> ,
cu(1C) <http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?cu+1> , uucp(1C)
<http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?uucp+1> , ioctl(2)
<http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?ioctl+2> ,
     gettydefs(4)
<http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?gettydefs+4> , inittab(4)
<http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?inittab+4> , tty(7)
<http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?tty+7> , serial(7)
<http://www.mcsr.olemiss.edu/cgi-bin/man-cgi?serial+7> 



DIAGNOSTICS


     Most error messages are sent to the system log, /var/adm/SYSLOG.  A
     message similar to

  getty[5310]: ioctl(TCSETAF)584: Invalid argument

     may indicate that the tty line does not support the baud rate
specified
     in /etc/gettydefs. See serial(7) for information on which baud
rates are
     supported.



BUGS


     While getty understands simple single character quoting
conventions, it
     is not possible to quote certain special control characters used by
     getty.  Thus, you cannot login via getty and type a #, @, /, !,
_<i>_,
     backspace, ^U, ^D, or & as part of your login name or arguments.
getty
     uses them to determine when the end of the line has been reached,
which
     protocol is being used, and what the erase character is.  They will
     always be interpreted as having their special meaning.



-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of mara ailiez sy
Sent: Wednesday, January 28, 2004 10:11 AM
To: [email protected]
Subject: Re: Re: About remote login


another question: what is getty prog?
 
 
 
You can  do that easily in C 
...  there is "getpass" routine for get your input without echoing ....
use gethostbyname , connect , send , recv  etc to connect to the remote
host ......
getty prog is useful here ...
 
As far as I remember "rlogin" source was included in one book by W
RICHARD STEVENS 
( unix n/w programming ???? ) .......
 
If you look at the RFC 1282 , it will give info about how to format the
messages  between the
 client/server .......
telnet's implementation is different from rlogin's 
 
-Nipun
 

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of mara ailiez sy
Sent: Wednesday, January 28, 2004 7:17 PM
To: [email protected]
Subject: about remote login


Hello... I am currently researching about remote login and came across
Python's Telnetlib. However, I cannot find a similar library in C. Does
anyone know if there is an equivalent library in C or the equivalent
functions can be implemented in C. 
 
Attached here is the sample code in Python that I want to implement in
C:
 
import getpass
import sys
import telnetlib

HOST = "localhost"
user = raw_input("Enter your remote account: ")
password = getpass.getpass()

tn = telnetlib.Telnet(HOST)

tn.read_until("login: ")
tn.write(user + "\n")
if password:
    tn.read_until("Password: ")
    tn.write(password + "\n")

tn.write("ls\n")
tn.write("exit\n")
 
thanks very much

print tn.read_all()
 



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