Not able to execute command in remote machine Using Net::SSH::Expect

Question

I wanted to make the remote connection and automate the change password of any user account in that remote machine so I am using Perl Net::SSH:: Expect module. My connection is happening but I'm not able to perform any command on the remote machine. I am new to Perl language so there might be some mistakes in my code. I have tried searching for this but wasn't able to find something related to it.

Initially, I tried using Net:: OpenSSH and Expect module in combination but wasn't able to achieve the use-case.

#!/usr/bin/perl

use strict;
use warnings;
use Net::OpenSSH;
use Expect;

use Net::SSH::Expect;

my $uName= "user";

my $ssh = Net::SSH::Expect->new (
    host => "IPAddress",
    password=> "userPassword",
    user => $uName,
    raw_pty => 1
);

# logon to the SSH server using those credentials.
my $login_output = $ssh->login();
if ($login_output !~ /Welcome/) {
    die "Login has failed. Login output was $login_output";
}
#Random line display 
print "Connected to $uName\n";

#This is where I was trying the change password use case

$ssh->send("passwd") or die "Cannot execute the passwd command: $!\n";
$ssh->waitfor("Changing password for user.\n
(current) UNIX password: ", 3) or die "prompt 'password' not found after 1 second";
$ssh->send("oldPassword\n");
$ssh->waitfor("\n
Enter new UNIX password: " , 2) or die "prompt 'New password:' not found";
$ssh->send("newPassword");
$ssh->waitfor("\n
Retype new UNIX password: ", 1) or die "prompt 'Confirm new password:' not found";
$ssh->send("newPassword");

#$ssh->send("") or die "Cannot spawn: $!\n";
$ssh->close();

This the output i am getting

Cannot execute the passwd command

New Update

I tried executing a simple command just to check whether any command is getting executed or not. It is but still, my change password use case using send(passwd) is not.

#!/usr/bin/perl

use strict;
use warnings;
#use Net::OpenSSH;
#use Expect;

use Net::SSH::Expect;

#
# You can do SSH authentication with user-password or without it.
#
my $uName= "admin1";
# Making an ssh connection with user-password authentication
# 1) construct the object
my $ssh = Net::SSH::Expect->new (
    host => "192.168.56.101",
    password=> "Passw0rd1",
    user => "admin1",
    raw_pty => 1
);

# 2) logon to the SSH server using those credentials.
# test the login output to make sure we had success
my $login_output = $ssh->login();
if ($login_output !~ /Welcome/) {
    die "Login has failed. Login output was $login_output";
}
print "Connected to $uName\n";

This is the new simple command i am trying to execute

my $who = $ssh->exec("who");
print ($who);

My old use case with die removed from send()

$ssh->send("passwd");
$ssh->waitfor("Changing password for $uName.\n(current) UNIX password: ", 2) or die "prompt 'password' not found after 2 second";
$ssh->send("Passw0rd1\n");
$ssh->waitfor("\nEnter new UNIX password: " , 2) or die "prompt 'New password:' not found";
$ssh->send("qwerty123");
$ssh->waitfor("\nRetype new UNIX password: ", 1) or die "prompt 'Confirm new password:' not found";
$ssh->send("qwerty123");


$ssh->close();

Now the output is coming like this

admin3@admin3-VirtualBox:~/Desktop$ perl NetSSHExpect.pl 
Connected to admin1
admin1   :0           2019-07-19 11:49 (:0)
admin1   pts/1        2019-07-19 12:41 (192.168.56.1)
admin1@admin1-VirtualBox:~$ prompt 'password' not found after 2 second at NetSSHExpect.pl line 36.
admin3@admin3-VirtualBox:~/Desktop$

Your waitfor patterns look odd. You have a newline character and then a literal newline: are you sure you need both? — glenn jackman, Jul 18 '19 at 22:57

score 1 · Accepted Answer · answered Jul 18 '19 at 22:48

1

According to the documentation:

void send($string) - sends $string to the SSH server, returns nothing
Sends the string to the SSH server.

So don't check the return value, just remove the or die .. part after the send():

$ssh->send("passwd");   # <-- no error code is returned here..

answered Jul 18 '19 at 22:48

Håkon Hægland

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I tried doing that but now my next waitfor die is prompting. I tried executing a simple command to check whether any command is executing or not. It is but the output is still what I expected. If you can just check the update of my question. – luffy008 Jul 19 '19 at 07:29
Try not include all the text in the `waitfor()` call. It still succeeds if only part of the string matches, and then it is less likely that there is something in the string that is slightly different from what the server echos, and then the `waitfor` will fail. For example: Try: `$ssh->waitfor("UNIX password: ") or die ...` – Håkon Hægland Jul 19 '19 at 11:18
1

Thanks now it's working after removing some of the words. – luffy008 Jul 19 '19 at 14:59

Not able to execute command in remote machine Using Net::SSH::Expect

New Update

1 Answers1