I am having problems forking. I have a loop that keeps calling a subroutine which has the forking code. For some reason it will work for the first couple loops and Perl goes to hell saying that things have not been inititalized... I tried using different Perl modules like thread and Parallel::ForkManager, but the same thing always happens. Here is my current code: 
#!/usr/bin/perl -w

use strict;
use IO::Socket;

my $threads;
my $pm;
my $class;
my $octect1 = 0;
my $octect2 = 0;
my $octect3 = 0;
my $octect4 = 0;
my $b;
my $c;
my $d;
my $host;
my $pid;
my @pids;
my $npids=0;
my $wait_ret;

if (@ARGV == 0){
 print "Test Subnet Scanner\n  Written by: Sapient2003\n\n";
 die "Usage: $0 subnet threads\n Class A: $0 66 100\n Class B: $0 66.4
+7 100\n Class C: $0 66.47.159 100\n";
}

($octect1, $octect2, $octect3, $octect4) = split '\.', $ARGV[0];
$threads = $ARGV[1];
$class = ($ARGV[0] =~ tr/.//);

if ($class == 0) {
 print "Processing Class A Scan";
 for($b = 0; $b<255; $b++){
  for($c = 0; $c<255; $c++){
   for($d = 0; $d<255; $d++){
    $host = "$octect1.$b.$c.$d";
   }
  }
 }
}
elsif ($class == 1) {
 print "Processing Class B Scan\n";
 for($c = 0; $c<255; $c++){
  for($d = 0; $d<255; $d++){
   $host = "$octect1.$octect2.$c.$d";
  }
 }
}
elsif ($class == 2) {
 print "Processing Class C Scan\n";
 for($d = 0; $d<255; $d++){
  $host = "$octect1.$octect2.$octect3.$d";
  checkhost($host);
 }
}
elsif ($class == 3) {
 print "Processing Single Host Scan\n";
 $host = "$octect1.$octect2.$octect3.$octect4";
}
else {die "Invalid class.\n";}

sub checkhost{
 $pid = fork();
 if($pid > 0){
  $npids++;
  if($npids >= $threads){
   for(1..($threads)){
    $wait_ret = wait();
    if($wait_ret > 0){
     $npids--;
    }
   }
  }
 next;
 }elsif(undef $pid){
   print "Forking error\n";
   exit(0);
 }else{
 print ".";
 my $host = shift;
 my $sock = new IO::Socket::INET(
    PeerAddr => $host,
    PeerPort => 80,
    Proto    => 'tcp',
    Timeout => 3);
 if ($sock){
  print $sock "GET / HTTP/1.0\n\n";
  while (<$sock>) {
   if (/^Server:\s*(.*)/) {
    print "\nFound: $host\n";
   }
  close($sock);
  }
 }
}
}

print "Done forking, $npids children remain.\n";

for(1..$npids){
 my $wt = wait();
 if($wt == -1){
  print "Hey $!\n";
  redo;
 }
}

print "Done!\n";

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In reply to Forking problems by Sapient2003

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