Although I often use ssh tunnels in curious ways such as this, I've never actually played with Net::SSH::Expect until now. I got this working just fine. I just rigged it up so that I can ssh from my workstation to box3 via localhost port 4101, I didn't bother trying other ports.

I switched the $ssh1 object method to run_ssh() because the lab machines I used to test this already have ssh keys set up already.

One thing that was very important, the sleep statements. It would not work until I put both of them in there. I'm assuming it must be some sort of race condition, but I'm not sure what the proper way to handle this.

And the $ssh_params I added are just arguments that I normally use to stuff ssh into the background when making tunnels.

#!/usr/bin/perl

use strict;
use warnings;
use Net::SSH::Expect;
use Data::Dumper;

my $user           = "user";
my $pwd            = undef;
my $localhost      = 'localhost';
my $first_host     = 'box1';
my $second_host    = 'box2';
my $third_host     = 'box3';
my $local_port_one = 4100;
my $local_port_two = 4101;
my $ssh_port       = 22;
my $raw_pty        = 1;
my $timeout        = 3;
my $ssh_params     = '-P -N -f ';    # send ssh to the background
my $rc;
my $rc2;


my $ssh1 = Net::SSH::Expect->new(

    host       => $first_host,
    password   => $pwd,
    user       => $user,
    raw_pty    => $raw_pty,
    timeout    => $timeout,
    ssh_option => "${ssh_params} -L ${local_port_one}:${second_host}"
                . ":${ssh_port}"
);

$Data::Dumper::Varname = 'rc_died_';
$rc = $ssh1->run_ssh() or die Dumper( @! );

sleep 1;

my $ssh2 = Net::SSH::Expect->new(

    host       => $localhost,
   #password   => "$pwd",
    user       => $user,
    raw_pty    => $raw_pty,
    timeout    => $timeout,
    ssh_option => "${ssh_params} -p ${local_port_one} -L "
                . "${local_port_two}:${third_host}:${ssh_port} ",
);

$Data::Dumper::Varname = 'rc2_died_';
$rc2 = $ssh2->run_ssh() or die Dumper( @! );

sleep 1;
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