Interesting problem. I had a similar one myself, except I don't really care which ones are up, just which ones are down, and I needed the results as a percentage so I could graph them.

I also discovered that trying to ping a huge number of hosts one at a time was painfully slow, so I wrote the following.

Bear in mind that this program is designed to pull the list of targets from a MySQL database, you could easily modify it to read in a config file though. It also doesn't handle forking the most efficient way possible, in that it doesn't ALWAYS keep $maxforks children running, it just runs them in bursts of $maxforks, but I find it's plenty fast enough even when pinging several hundred targets. I also used the system call to ping instead since I couldn't install CPAN modules on the machine it was running on. Again, that's probably a three-minute change.

Hope you find it interesting...

#!/usr/bin/perl --
#
# ForkingPinger
# Pings a list of remote hosts and calculates an uptime 
# percentage based on the number of responses. If run in
# interactive mode, lists the sites that failed.
#
# (C) 2001 James Mancini <wfe@networkavatar.com>
# Please send copies of modifications or improvements to 
# the author!
#
# Released under the same terms as perl itself.
#
# THIS PROGRAM IS PROVIDED WITH NO WARRANTY - USE AT YOUR
# OWN RISK.
#
# 21 Mar 2001

my $Version = "0.2.2 - beta";
use DBI;
use Getopt::Long;
use POSIX ":sys_wait_h";

$|++;       #autoflush output for speed
#########################
# MAIN
#########################
    
my (%opt, @targets);
my $maxprocs = $opt{max} || 50;    # set the maximum number of childre
+n to spawn
$main::avail = 0;

&options(\%opt);
&get_targets();
&check_remotes();


#########################
sub get_targets
#########################
{
## Set up vars for main db call
my ($dsn) = "DBI:mysql:routers:localhost";
my ($user_name) = "user";
my ($password) = "abcd1234";
my ($dbh, $sth);

## Connect to DB
$dbh = DBI->connect ( $dsn, $user_name, $password, {RaiseError =>1} );

## Fetch variables from database and write out config file

## The Database Query is option dependant
if ($opt{cat})
{
    $sth = $dbh->prepare ("SELECT ip FROM routers WHERE category rlike
+ '$opt{cat}'");
} elsif ($opt{all}) {
    $sth = $dbh->prepare ("SELECT ip FROM routers");
} else { die "ERROR - Couldn't identify a target. $!"; }

## Go get it
$sth->execute();

## Process the data
while( ($ip_add) = $sth->fetchrow_array() )
 {
   push @targets, $ip_add;
   $noerror = "1";
 }

## Disconnect the DB
$sth->finish ();
$dbh->disconnect();
unless ($noerror) {die "FATAL: Database did not return valid data! Che
+ck Device name.\nError Response: $!\n";}

}

#########################
sub check_remotes
#########################
{

my $prox = int(scalar(@targets)/$maxprocs);
my $prox_r = int(scalar(@targets)%$maxprocs);
my $i = 0;

if ($prox)
 {
  for ( 1 .. $prox )  # call the forking routine as many times as requ
+ired to get most of the targets
   {
    &breed($maxprocs);  
   }
 }
if ($prox_r) 
 {
  &breed($prox_r);    # Then call the forking routine but this time on
+ly enough to catch the modulo
 }

# Calculate results and print to STDOUT
my $uptime = ( $main::avail / scalar(@targets) ) * 100;   # return res
+ults as a percentage
$uptime = sprintf('%.2f',$uptime);
print "\nTOTAL:\t${uptime}% of devices are responding.\n";
}

#########################
sub breed ($)
#########################
{
    my $loop = shift;
    for ( 1 .. $loop )
     {
       if ($pid=fork) {
           push @pids, $pid;
           $i ++; 
       } elsif (defined $pid) {
           my $next = @targets[${i}];
           &ping_remote($next);
           exit;
       }
     }
   foreach my $childpid (@pids) 
   {
    waitpid($childpid, 0);
    $main::avail += ! $?;   # 0 means success, non-zero means failure
   }
}

#########################
sub ping_remote($)
#########################
{
my $ip = shift;
my $response = `ping -n -w 5 -i .3 $ip -c 3 | grep round-trip`;
chomp $response;
if ($response) { $response = 0; } else { $response = 1; } # 0 means su
+ccess, non-zero means failure
if (-t and $response) { print "Failed connect to $ip\n"; }
exit($response);
}

########################
sub options () 
########################
{
   my $opt = shift;
   GetOptions( $opt,
        'cat=s',
        'max=s',
        'all',
             ); 

   $opt{cat} =~ s/[\"\;]//; # remove quotes and semicolons from querie
+s             
   unless (defined $opt{cat} || $opt{all}) #print usage if options not
+ given
    {
     print <<ECHO;
     
ForkingPinger, Version $Version
---------
Pulls a category from the database and checks it for availability, ret
+urning a percentage.

Designed to be run in batch mode but can be used at the command line f
+or debugging or testing purposes. Highly parallel. 

Automatically prints the IP addresses of failed sites if used from the
+ command line.

Usage: $0 [options]

Options:

 --cat=name       
Pull all devices of category matching regexp 'name' from DB and test a
+vailability.

 --all        
Pull all devices from DB and test availability.


 --max=num        
Spawn no more than num processes in parallel         (default = 50)


ECHO
exit(1);
    }

}
[download]

Update: Fixed a little typo I spotted. Oops.
Update2: Fixed a bigger omission: the -all switch was broken. I wasn't considering the option when validating command line switches. Oops again.

---

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