my $thr = threads->new(\&check_fw_logs);
my @ReturnData = $thr->join;
print "Thread returned @ReturnData";

sub check_fw_logs {

 my @ips;

 open (FILE, $fw_file) or croak("Can't open $fw_file: $!\n");
 while(<FILE>){
  for my $i (@allips){
    push(@ips, $_) if /$i/;
  }
 }
 return @ips;
}