use warnings;
use Getopt::Std;
use Net::SNMP;
use Data::Dumper;
use Net::Ping;
use Parallel::ForkManager qw( );
use Fcntl qw(:flock);
use Socket qw( inet_aton );

#Declare the variables
my $desc = '1.3.6.1.2.1.1.5.0'; 
my $host;
my $pingable = "pingable.txt";
my $numOfProc = 25;
my $manager = Parallel::ForkManager->new($numOfProc);

#declare the desired host range
my @sn_array = ("7.3.1.");

my ($session, $error, %pdesc, $respnse);

#delete the previously created file
if (-e "pingable.txt"){
	unlink "pingable.txt";
}
#ping the host array and write to a file
foreach $host (@sn_array){  
	 for ($s=1; $s<255; $s++){
	 		$manager->start and next;
	 		my $p = Net::Ping->new("icmp");
    		$host = $host . $s;
    		print "pinging $host\n";
	if ($p->ping($host)){
			open PingFile, ">>", "$pingable" or die $!;
			flock(PingFile, LOCK_EX);
			print PingFile "$host\n";
			flock(PingFile, LOCK_UN);
	 		close(PingFile);
	 	}
	$manager->finish;
	 }
}

sleep(5);

#count the new host ips in the file
my $pingCount;
	open PINGFILE, "<", "$pingable";
		$pingCount++ while(<PINGFILE>);
	close PINGFILE;

# if there are new hosts in the file, scan them Cisco HostName OID and print it out
if ($pingCount > 1) {
	open PINGFILE, "<", "$pingable";
	while(<PINGFILE>) { 
   		 chomp; 
    push @file, $_;
	} 
foreach my $host (@file) {
	&snmpwalk($host);
	}
}

#sub to get the Cisco host name OID and print it out
sub snmpwalk{
($session, $error) = Net::SNMP->session(                   
 -hostname => shift,                  
 -community => "public",                
 -timeout  => "5",                  
 -port => "161");  

if (!defined($session)) {       
  printf("ERROR: %s.\n",  $error);     
  exit 1; } 

my $response = $session->get_request($desc); 

if (!defined $response) {
         printf "ERROR: Get request failed for host '%s': %s.\n",
                $session->hostname(), $session->error();
         return;
  }
  
my %pdesc = %{$response}; 
 for my $key ( keys %pdesc ) {
        my $value = $pdesc{$key};
        print "$value\n";
    }

my $err = $session->error; 

if ($err){    return 1; } 


}