#!/usr/bin/perl
use Net::Ping;
use Socket;
#*********************************************************************
# pinger : Ping C-Class Ip's in the following subnets (@subnets)
# 
# Description: ping hosts in the listed  subnets and report to STDOUT
#  
# Modified an existing pid fork ping script written by Randal Scwartz 
# Octet range listed is set for my building removed
# broadcast octets as well as unused hosts in low range.
#
# Donald J. Reckinger Mon Aug  5 15:57:04 EDT 2002
#*********************************************************************


@subnets = (1,2,3,4,5,6,7);
     foreach $subnet (@subnets) {
         for ($octet=20; $octet <= 254; $octet++) {
       push @hosts, "192.168.$subnet.$octet";
      }
}

sub ping_a_host {
$p = Net::Ping->new("icmp");
($p->ping($host,2)) =~ /1/ ? 1 : 0;
$p->close();
}

my %pid_to_host;
my %host_result;

sub wait_for_a_kid {
$p = Net::Ping->new("icmp");
my $pid = wait;
return 0 if $pid < 0;
my $host = delete $pid_to_host{$pid}
or warn("Why did I see $pid ($?)\n"), next;
warn "stopping $pid for $host\n";
$host_result{$host} = ($p->ping($host,2)) =~ /1/ ? 1 : 0;
1;
}

 for (@hosts) {
    wait_for_a_kid() if keys %pid_to_host > 10;
    if (my $pid = fork) {
    ## parent does...
    $pid_to_host{$pid} = $_;
    warn "$pid is processing $_\n";
    } else { # child does
## child does...
    exit !ping_a_host($_);
    }
}
## final reap:
                 1 while wait_for_a_kid();

for (sort keys %host_result) {
chomp(my $claimed_hostname = gethostbyaddr(inet_aton($_ ),AF_INET)); 
print "$_ aka $claimed_hostname is ", ($host_result{$_} ? "good" : "ba
+d"), "\n";
    }

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In reply to Scan C Subnets for /up/down hosts and resolve names in DNS by /dev/null

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