use Net::Telnet;
use strict;

my $username = "standarduser";
my $passwd = "standardpass";
my $base = "10.20.16";
my $start = 0;
my $end = 256;
my $t = new Net::Telnet (Timeout => 1,
                         Prompt => '/<.> $/',
                         Errmode => 'return');

if (defined $ARGV[0]){
    $start = $ARGV[0];
}
if (defined $ARGV[1]){
    $end = $ARGV[1];
}

for (my $i=$start; $i<$end; $i++){
  $t->close unless $i==$start;
  print "Trying $i\n";
  next unless $t->open("$base.$i");
  next unless $t->login($username, $passwd);
  my @lines = $t->cmd("pwd");
  print "$base.$i => $lines[1]\n"; #next command prompt
}