my $timeout = 50;
use Expect;

$Expect::Exp_Internal = 1;
$Expect::Debug = 1;

my $conn = Expect->new;
   $conn->raw_pty(1);
   $conn->log_user(0);

$conn->spawn('/usr/bin/ssh', -l => 'USERNAME', 'IPADDRESS', -s => 'sftp') or die "Cannot spawn : $!";

$conn->expect($timeout, "Password:") or die "Password not requested as expected";
$conn->send("PASSWORD\n");
$conn->expect($timeout, "\n");

my $sftp = Net::SFTP::Foreign->new(transport => $conn);
die "unable to stablish SSH connection: ". $sftp->error

# The rest is the same as above