ping

#!/usr/bin/perl

=begin metadata

Name: ping
Description: probe for network hosts
Author: Nick Ing-Simmons, nick@ni-s.u-net.com
License: perl

=end metadata

=cut


use strict;
use Getopt::Std;
use Socket;
use Net::Ping;

sub usage {
    require Pod::Usage;
    Pod::Usage::pod2usage({ -exitval => 1, -verbose => 0 });
}

my %opt;
getopts('nI:', \%opt) or usage();
my $host = shift;
my $timeout = shift;
usage() unless defined $host;
$timeout = 20 unless defined $timeout;
usage() if @ARGV;

my $a = gethostbyname($host);

if ( $a ) {

	if ( $opt{'n'} ) {

		my $name = inet_ntoa($a);
    	$host = $name if ($name);

   } else {

	   my $name = gethostbyaddr($a,PF_INET);
       $host = $name if ($name);
   }

   my $handle = Net::Ping->new($> ? 'udp' : 'icmp', $timeout);

   if ( $handle->ping($host) ) {

	   warn "$host is alive\n";

   } else {

	   die "No answer from $host";
   }
 } else {

	die "Unknown host $host\n";
}

__END__

=head1 NAME

ping - probe for network hosts

=head1 SYNOPSIS

  ping [-n] hostname [ timeout ]

=head1 DESCRIPTION

C<ping> looks up I<hostname> and then attempts to contact it via the network.
If the effective userid permits an ICMP (Internet Control Message Protocol)
ECHO_REQUEST packet is sent, otherwise and attempt is made to connect to
the echo port using UDP protocol.

A I<timeout> may be specified in seconds. The default is 20 seconds.

If C<-n> option is specified then the address of I<hostname> is reported
as numbers.

=head1 AUTHOR

Nick Ing-Simmons <nick@ni-s.u-net.com>

=cut