my @temparr = ($packets[$pnum] =~ /$str/g);

##</code><code>##

my @temparr = ($packets[$pnum] =~ /\Q$str\E/g);

##</code><code>##

foreach my $p (@packets) {
  foreach my $l (2..length($p)) {
    foreach my $pos (0..length($p)-$l) {
      my $str=substr($p, $pos, $l);
      $all{$str}+=$_ for map { scalar(($_ =~ /\Q$str\E/g)) } @packets;
    }
  }
}