• BackTrack 5 r1

#!/usr/bin/perl

use warnings;
use strict;
use Net::Ping;

my $host = "10.20.30.40";
my $event = "/usr/bin/truecrypt --text --dismount --force > /dev/null 2>&1";
my $cnt = 0;
use vars qw/$host $event $cnt/;

while ( 0 == 0 ) {
  my $p = Net::Ping->new();
  if ( $p->ping( $host ) ) {
    $cnt = 0;
  } else {
    ++$cnt;
  }
  system( $event ) if ( $cnt > 6 );
  $p->close();
  sleep( 10 );
}