MysticRyuujin has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to create a module for connecting to our Cisco devices. My problem is that if I connect via the module the connection is closed when the module subroutine is done (I think.)

This is the first module I've ever tried to create. The login_auth subroutine works perfectly fine if I put it into the scrip directly, and it appears to do exactly what I want when I run it (it does log in and authenticate). However, the rest of the script doesn't do anything because it seems like the interactive session isn't being passed through. I have a lot of scripts for various things that use it over and over and I want to create a module to just call common subroutines like that.

The Script:

#!/usr/bin/perl -w

use lib '/enm01/custom/scripts/modules';
use Expect;
use cisco qw(&login_auth);;

my $exp = new Expect;

# Parces the BASH arugments into Perl variables
( $UNAME, $PWD, $ENABLE, $DNAME, $IP, $LOG ) = @ARGV;

# This logs in and authenticates to the device
login_auth(@ARGV);

# This checks to make sure the hostname is correct
namecheck();

sub namecheck
{
        if ( $DNAME !~ /U....WX[0-9][0-9]/ )
        {
                $exp->send("show run | include hostname\n");
                @hostintval = $exp->expect( 10,"#");
                $newmatch = $hostintval[3];
                @hostname = split(m[ |\n],$newmatch);
                foreach(@hostname)
                {
                 if ( ($_ !~ m/^hostname$|^show$|^run$|\||^include$|^$
+|\cM$/) )
                        {
                                if ( $DNAME ne $_ )
                                {
                                        print LOG "$DNAME" . " is inco
+rrect please change to " . "$_\n";
                                        $DNAME = $_;
                                }
                        }
                }
        }
}

[download]

The Module: 

package cisco;

use strict;
use Exporter;
use Expect;

use vars qw( $VERSION @ISA @EXPORT @EXPORT_OK $UNAME $PWD $ENABLE $DNA
+ME $IP $LOG $command $result $exp );

$VERSION     = 1.00;
@ISA         = qw(Exporter);
@EXPORT      = ();
@EXPORT_OK   = qw(login_auth);

( $UNAME, $PWD, $ENABLE, $DNAME, $IP, $LOG ) = @ARGV;

$exp = new Expect;

open( LOG, ">>$LOG" );

sub login_auth
{
        $command = "ssh $UNAME" . "@" . "$IP";
        $exp->spawn($command) or die "Cannot spawn $command: $!\n";

        my $connect = $exp->expect
        (
                30,
                [ qr/\(yes\/no\)\?\s*$/ => sub { $exp->send("yes\n"); 
+exp_continue; } ],
                [ qr/assword:\s*$/ => sub { $exp->send("$PWD\n"); } ],
        );
        $result = $exp->expect(30, "#", ">");
        if ($result == 2)
        {
                $exp->send("enable\n");
                $result = $exp->expect(30, "assword:", "#");
                if ($result == 1)
                {
                        $exp->send("$ENABLE\n");
                        $result = $exp->expect(30, "assword:", "#");
                        if ($result == 1)
                        {
                                print LOG "Enable Password Rejected\n"
+;
                                exit();
                        }
                }
        }
$exp->send("term len 0\n");
$exp->expect(10,"#");
}

1;

[download]

Replies are listed 'Best First'.
Re: SSH connection with module
by NetWallah (Canon) on Mar 10, 2014 at 01:22 UTC
    You are not persisting an object and associated states.

    You end up creating two completely separate Expect objects.

    You should create a cisco::new() method that creates an object (see 'perldoc perltoot') - this method should look something like this: 

    sub new{
  my ($class, $logname) = @_;
  $logname or die "NO log file name specified";
  my $self = bless {}, $class; # Creating an empty instance
  $self->{EXP} = Expect::->new(); # Now has an EXP attribute
  open   $self->{LOGFH}, ">>", $logname or die "Could not append to $l
+ogname : $!";
  return $self;
}

    [download]
    Once you get an object back from new(), you need to call login_auth like this: 
      my $cisco = cisco::->new();
  $cisco->login_auth();

    [download]
    Of course, you will need to modify login_auth() to accept a parameter, preferably named $self.

    Update: Added LOG to new() method.

    So happy journey into the world of OO programming!

    If you run into concept issues with how or why things are done is a certain way, be sure to post specific questions here, for assistance.

            What is the sound of Perl? Is it not the sound of a wall that people have stopped banging their heads against?
                  -Larry Wall, 1992

[reply]
[d/l]
[select]
      I got most of that but I have no idea what you mean by "you will need to modify login_auth() to accept a parameter, preferably named $self." Don't I have to use this because I have to pass the variables: 
      $cisco->login_auth(@ARGV);

      [download]
      I get that sub new is returning an object into the main script but I don't get how I then pass it back to the module and use it then pass it back? Am I even understanding that right?
[reply]
[d/l]
        Yes - you are asking the right questions - so you are close to "getting it".

        When you invoke 

          $cisco->login_auth( $whatever );

        [download]
        you are actually passing TWO parameters into login_auth - which you can retrieve using: 
        sub login_auth{
  my ($self, $whatever) = @_;
  # Now $self contains whatever sub new() put into it.
  # and $self can be updated to include more useful things.
}

        [download]
        Instead of passing @ARGV, you should pass it as a reference : \@ARGV.

        This will allow passing additional parameters if necessary.

        OK - next question ?...

                What is the sound of Perl? Is it not the sound of a wall that people have stopped banging their heads against?
                      -Larry Wall, 1992

[reply]
[d/l]
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