Ok. Well here is something that is near what I assume you are looking for.
Except, it doesn't branch on a QUERY_STRING, and of course I am not using CGI.pm.

If you so need to do that. Then you may like to branch your code via something from $ENV{QUERY_STRING}. Or even better, use CGI.pm. And have branching from something like this :

use CGI qw/:standard/;
my $cgiObj = new CGI;
my $addr_to_ping=$cgiObj->param('ip_address');
[download]

The url with the CGI param would look something like this : http://some-site.net/client.pl?ip_address=66.39.54.27

Client/CGI script/Ping output (to a Web browser) This works for me.

#!/usr/bin/perl
#Client Script
use strict;
use IO::Socket;

print "Content-type:text/html\n\n";

my $server="192.168.0.101";
my $server_port=23;
my $nodeName = "192.168.0.101";
my $sock = new IO::Socket::INET (PeerAddr =>$server,
                              PeerPort => $server_port ,
                              Proto    => 'tcp',
                             ) or do_exit("Couldn't connect to $server
+:$server_port.\n");

print $sock "ping:$nodeName\n";
while(my $server_response=(<$sock>)) {
    chomp($server_response);
    print "Server said: $server_response<BR>" if($server_response);
    if($server_response eq "MOK") {
        exit(0);
    }
}

sub do_exit {
    my $err_msg=$_[0];
    print "$err_msg";
    exit(1);
}
[download]

Server/pinger

#!/usr/bin/perl
#Server Script
use warnings;
use strict;
use IO::Socket;
use IO::Select;
use Net::Ping;

my $serverport = 23;
# create a socket to listen on SOMAXCONN = 512
my $server = new IO::Socket(
    Domain => PF_INET,
    Proto => 'tcp',
    LocalPort => $serverport,
    Listen => SOMAXCONN,
);
die "Cannot bind: $!\n" unless $server;

# create a 'select' object and add server fh to it
my $selector = new IO::Select($server);
# stop closing connections from aborting the server
$SIG{PIPE} = 'IGNORE';

# loop and handle connections
print "Multiplex server started on port $serverport...\n";

while (my @clients = $selector->can_read) {

# input has arrived, find out which handles(s)
foreach my $client (@clients) {
    if ($client == $server) {
        # it's a new connection, accept it
        my $newclient = $server->accept;
        my $port = $newclient->peerport;
        syswrite $newclient, "Welcome!\n";
        my $name = $newclient->peerhost;
        $selector->add($newclient);
    }else{
        # it's a message from an existing client
        my $port = $client->peerport;
        my $name = $client->peerhost;
        my ($message, $buf, $host);
        my $newclient = $client->accept;
        my $reach = Net::Ping->new($ > ? "tcp": "icmp");
        (defined $reach) or die "Couldn't create Net::Ping object: $!\
+n";
        if (sysread $client, $message, 1024) {
            print "Client $name:$port sent: $message";
            while (defined ($buf = <"$message">)) {
                $host = (split(/:/,$buf))[1];
                chomp($host);
                print "Remote IP to be pinged $host\n";
                if($reach->ping("$host")) {
                    print "$host is reachable\n";
                    print $client "reachable $host\n";
                }else{
                    print "$host is unreachable\n";
                    print $client "unreachable $host\n";
                }
            }
            print $client "\n Message received OK\n";
        }else{
            $selector->remove($client);
            $client->shutdown(SHUT_RDWR);
            print "\nClient disconnected\n"; # port, name not defined
        }
    }
}
}
[download]