Use the Net::Telnet module

use warnings;
use Net::Telnet ();
my ($hostname, $username, $passwd);
$hostname = "192.168.120.48";
$username = "cnshroot";
$passwd = "shroot";
$telnet = new Net::Telnet (Timeout => 10,
                      Prompt => '/-bash-3\.00# $/');
$telnet->open($hostname);
$telnet->login($username, $passwd);
@lines = $telnet->cmd("who");
print @lines;
$telnet->close;
exit;