Net::Telnet ()报等待prompt 超时的错

CODE:

#!/usr/bin/perl -w

use Net::Telnet ();

$timeout = 5;
$port = 23;
$host = '10.100.2.32';
$user = '123';
$pw = '123';

$t = new Net::Telnet (Timeout => $timeout,
                      Port    => $port,
                      Prompt => '/(\$|\#|\>) $/');
$t->open($host);
$t->login($user, $pw);
@lines = $t->cmd("who");
print @lines;