[Expectperl-discuss] Problem connecting with ssh

[Zippy <spa...@ya...>]

I'm not able to get the script below to work.  It is
trying to connect to a host via ssh.  It is supposed
to wait for the password prompt and then send a valid
password, but for some reason it looks like the first
line that I read in is "Permission denied, please try
again." Since waiting for the password prompt kept
failing, I did a getline() as soon as the ssh object
was created and received "Permission denied, please
try again."  If I use RSA keys and remove the log in
portion of the script, everything works fine.  It is
just the initial connection. It acts like, before I
can send my password, it is automatically sending
something and entering it.  Does anyone know what is
going on?  Thanks for any help.


#!/usr/bin/perl
# Figure 6.6: Changing passwords over a Secure Shell
connection
# file: change_passwd_ssh.pl

use strict;
use Net::Telnet;
use Getopt::Long;
use IO::Pty;
use POSIX 'setsid';

use constant PROMPT  => '/[\$%#>] $/';
use constant DEBUG => 1;

my $user = shift || $ENV{LOGNAME};
#my $old = get_password('old password');
#my $new = get_password('new password');

my $old = "*****";
my $new = "*****";

my $host = shift;

change_passwd($host,$user,$old,$new);

sub change_passwd {
  my ($host,$user,$oldpass,$newpass) = @_;
  my $ssh = do_cmd('ssh',$host)
    or die "couldn't launch ssh subprocess";

  my $shell = Net::Telnet->new(Fhopen => $ssh);
  $shell->binmode(1);
  $shell->input_log('passwd.log') if DEBUG;
  $shell->dump_log('dump.log') if DEBUG;
  $shell->errmode('return');

  my $line = $shell->getline();
  print "line=$line\n";
  $shell->waitfor('/password: $/') or return
$shell->errmsg,"\n";   *******problem occurs
here*******
  $shell->print($oldpass);
  $shell->waitfor(PROMPT) or return "host refused
login: wrong password?\n";
  $shell->print('passwd');
  $shell->waitfor('/password:/') or return warn
"$host: ",$shell->errmsg,"\n";
  $shell->print($oldpass);
  my($pre,$match) = $shell->waitfor(Match =>
'/error/',
                                    Match =>
'/password:/');
  $match =~ /password/ or return warn "$host:
Incorrect password.\n";
  $shell->print($newpass);
  ($pre,$match) = $shell->waitfor(Match => '/Bad
password/',
                                  Match => '/Retype
new password:/');
  $match =~ /Retype/ or return warn "$host: New
password rejected.\n";
  $shell->print($newpass);
  $shell->waitfor('/successfully\./')
    or return warn "$host: ",$shell->errmsg,"\n";
  print "Password changed for $user on $host.\n";
}

sub do_cmd {
  my ($cmd,@args) = @_;
  my $pty = IO::Pty->new or die "can't make Pty: $!";
  defined (my $child = fork) or die "Can't fork: $!";
  return $pty if $child;

  setsid();
  my $tty = $pty->slave;
  close $pty;

  STDIN->fdopen($tty,"r")      or die "STDIN: $!";
  STDOUT->fdopen($tty,"w")     or die "STDOUT: $!";
  STDERR->fdopen(\*STDOUT,"w") or die "STDERR: $!";
  close $tty;
  $| = 1;
  exec $cmd, @args or die "Couldn't exec: $!";
}