Re: [Expectperl-discuss] Nested telnet sessions using Expect.pm module

[Chris M. <mut...@mc...>]

Hi,

>Did you write something like this before. Can I have an example?
Yes I did.  Sure, here it is.

This is more than an example, It is a fully working implementation of a so=
 called "looping login" scheme.
It works for an arbitrary number of hosts.  It was also designed to work=
 with ssh, and not telnet.
You will have to go through and make the relevant changes to make it work=
 with telnet.
Optionally, you might consider using ssh -if possible-, as it is more=
 secure than telnet.

This will log you into all of the given hosts and leave you with a $exp=
 that is valid on the final host.

This is a subroutine.  The usage explanation of it is at the bottom of the=
 code segment.

I hope this helps.

-Chris Muth

####
#### START OF CODE
####
#!/usr/bin/perl5.8 -w

use Expect;   # for scripted I/O

# req global; $exp, $number_of_hosts, $hostname[], $password[],
sub multi_login {

   my($i,$j);

   for ($i=3D0;$i<$number_of_hosts;$i++){
      if ($i=3D=3D0){
         $exp->spawn("/usr/local/bin/ssh",$hostname[$i]);
      } else {
         $exp->send("/usr/local/bin/ssh ".$hostname[$i]."\n");
      }

      $retval =3D $exp->expect(30,'-re','word:\s$','Connection refused','No=
 route to host','Name or service not known');
      if (defined $retval){
         if ($retval !=3D 1) { # $retval is 2 or 3.
            if ($retval =3D=3D 2){ # $retval is 2, "Connection refused".
               if ($i > 0){
                  for ($j=3D0;$j<$i;$j++){
                     $exp->send("logout\n");
                  }
               }
               print "connection refused for ".$hostname[$i];
               $exp->hard_close();
               exit 1;
            } else {
               if ($retval =3D=3D 3){ #$retval is 3, "No route to host".
                  if ($i > 0){
                     for ($j=3D0;$j<$i;$j++){
                        $exp->send("logout\n");
                     }
                  }
                  print "there is no route to host ".$hostname[$i];
                  $exp->hard_close();
                  exit 1;
               } else { # $retval is 4, 'Name or sevice not known'
                  if ($i > 0){
                     for ($j=3D0;$j<$i;$j++){
                        $exp->send("logout\n");
                     }
                  }
                  print "Name or service not known for host=
 ".$hostname[$i];
                  $exp->hard_close();
                  exit 1;
               }
            }
         } # $retval is 1, we got the password prompt.
      } else { # $retval is undefined, ssh didn't respond with anything=
 within 30 seconds.
         if ($i > 0){
            for ($j=3D0;$j<$i;$j++){
               $exp->send("logout\n");
            }
         }
         print "ssh did not respond";
         $exp->hard_close();
         exit 1;
      }

      $exp->send($password[$i]."\n");
      $retval =3D $exp->expect(30,'# ','Permission denied');
      if (defined $retval){
         if ($retval =3D=3D 2){ # $retval is 2, we got a permission denied=
 message.
            if ($i > 0){
               for ($j=3D0;$j<$i;$j++){
                  $exp->send("logout\n");
               }
            }
            print "permission denied for login to ".$hostname[$i];
            $exp->hard_close();
            exit 1;
         } # $retval is 1, we got the prompt.
      } else { # Got neither a prompt, nor a permission deined message.
         if ($i > 0){
            for ($j=3D0;$j<$i;$j++){
               $exp->send("logout\n");
            }
         }
         print "error on login to ".$hostname[$i];
         $exp->hard_close();
         exit 1;
      }
   }
}

# instiantiate an Expect object that we will use.
$exp =3D new Expect;
$exp->raw_pty(1);

# for use by multi_login(), how many hosts to login to.
$number_of_hosts =3D 3;

#  List all of the hosts to login to.  Start at 0.
$hostname[0] =3D 'host0';
$hostname[1] =3D 'host1';
$hostname[2] =3D 'host2';

#  List all of the passwords for the hosts to be logged into.  Again, start=
 at 0.
$password[0] =3D 'pass0';
$password[1] =3D 'pass1';
$password[2] =3D 'pass2';

# Call multi_login(), it will use $exp, $number_of_hosts, $hostname[], and=
 $password[].
multi_login();

# From here on out, $exp is valid on hostname[<max>].
# Just use it as normal.

# Modify the prompt to something easy to match, and easy on bandwidth.
$exp->send("PS1=3D\"# \"\nexport PS1\n");
$exp->expect(30,'# ');
$exp->expect(30,'# ');

$exp->send("ls -l\n");
$exp->expect(30,'# ');
# this will make expect wait, as sleep() does not work with expect scripts.
$exp->expect(5,'this call will make expect sleep');

$exp->hard_close();
print "\n";
exit 0;
#####
#####  END OF CODE
#####