External(3pm)						User Contributed Perl Documentation					     External(3pm)

NAME

       Net::Ping::External - Cross-platform interface to ICMP "ping" utilities

SYNOPSIS

       In general:

	 use Net::Ping::External qw(ping);
	 ping(%options);

       Some examples:

	 use Net::Ping::External qw(ping);

	 # Ping a single host
	 my $alive = ping(host => "127.0.0.1");
	 print "127.0.0.1 is online" if $alive;

	 # Or a list of hosts
	 my @hosts = qw(127.0.0.1 127.0.0.2 127.0.0.3 127.0.0.4);
	 my $num_alive = 0;
	 foreach (@hosts) {
	   $alive = ping(hostname => $_, timeout => 5);
	   print "$_ is alive!
" if $alive;
	   $num_alive++;
	 }
	 print "$num_alive hosts are alive.
";

	 # Using all the fancy options:
	 ping(hostname => "127.0.0.1", count => 5, size => 1024, timeout => 3);

DESCRIPTION

       Net::Ping::External is a module which interfaces with the "ping" command on many systems. It presently provides a single function,
       "ping()", that takes in a hostname and (optionally) a timeout and returns true if the host is alive, and false otherwise. Unless you have
       the ability (and willingness) to run your scripts as the superuser on your system, this module will probably provide more accurate results
       than Net::Ping will.

       Why?

       o   ICMP ping is the most reliable way to tell whether a remote host is alive.

       o   However, Net::Ping cannot use an ICMP ping unless you are running your script with privileged (AKA "root") access.

       o   The system's "ping" command uses ICMP and does not usually require privileged access.

       o   While it is relatively trivial to write a Perl script that parses the output of the "ping" command on a given system, the aim of this
	   module is to encapsulate this functionality and provide a single interface for it that works on many systems.

   ping() OPTIONS
       This module is still "alpha"; it is expected that more options to the "ping()" function will be added soon.

       o   "host, hostname"

	   The hostname (or dotted-quad IP address) of the remote host you are trying to ping. You must specify either the "hostname" option or
	   the "ip" option.

	   "host" and "hostname" are synonymous.

       o   "ip"

	   A packed bit-string representing the 4-byte packed IP address (as returned by "Socket.pm"'s "inet_aton()" function) of the host that
	   you would like to ping.

       o   "timeout"

	   The maximum amount of time, in seconds, that "ping()" will wait for a response.  If the remote system does not respond before the
	   timeout has elapsed, "ping()" will return false.

	   Default value: 5.

       o   "count"

	   The number of ICMP ping packets to send to the remote host. Eventually, Net::Ping::External will return the number of packets that were
	   acknowledged by the remote host; for now, however, "ping()" still returns just true or false.

	   Default value: 1.

       o   "size"

	   Specifies the number of data bytes to be sent.  The default is 56, which translates into 64 ICMP data bytes when combined with the 8
	   bytes of ICMP header data.

	   Default value: 56.

   SUPPORTED PLATFORMS
       Support currently exists for interfacing with the standard ping utilities on the following systems. Please note that the path to the `ping'
       should be somewhere in your PATH environment variable (or your system's closest equivalent thereof.) Otherwise, Net::Ping::External will be
       unable to locate your system's `ping' command.

       o   Win32

	   Tested OK on Win98, Win XP. It should work on other Windows systems as well.

       o   Cygwin

	   Tested OK on Cygwin 1.5.21. Problem is that we may be running windows ping.	They have different options.

       o   Linux

	   Tested OK on Debian 2.2 and Redhat 6.2. It appears that different versions of Linux use different versions of ping, which support
	   different options.  Not sure how I'm going to resolve this yet; for now, all the options but "count" are disabled.

       o   BSD

	   Tested OK on OpenBSD 2.7 and 3.0, Netbsd 1.5.3, Freebsd 4.6.2, 5.4. Needs testing for BSDi.

       o   Solaris

	   Tested OK on Solaris 2.6 and 2.7.

       o   IRIX

	   Tested OK on IRIX 6.5.

       o   AIX, DEC OSF, UNICOSMK, NeXTStep, HP-UX, BSD/OS (BSDi), BeOS

	   Support for these systems is integrated into this module but none have been tested yet. If you have successful or unsuccessful test
	   results for any of these systems, please send them to me. On some of these systems, some of the arguments may not be supported. If
	   you'd like to see better support on your system, please e-mail me.

       More systems will be added as soon as any users request them. If your system is not currently supported, e-mail me; adding support to your
       system is probably trivial.

BUGS

       This module should be considered beta. Bugs may exist. Although no specific bugs are known at this time, the module could use testing on a
       greater variety of systems.

       See the warning below.

WARNING

       This module calls whatever "ping" program it first finds in your PATH environment variable. If your PATH contains a trojan "ping" program,
       this module will call that program. This involves a small amount of risk, but no more than simply typing "ping" at a system prompt.

       Beware Greeks bearing gifts.

AUTHOR

       Alexandr Ciornii (alexchorny AT gmail.com), Colin McMillen (colinm AT cpan.org)

       This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

CREDITS

       Dan Moore contributed command-line options and code for NeXT, BeOS, HP-UX, and BSD/OS.

       Jarkko Hietaniemi contributed a huge list of command-line options and results for the `ping' command on 9 different systems.

       Randy Moore contributed several patches for Win32 support.

       Marc-Andre Dumas contributed a patch for FreeBSD support.

       Jonathan Stowe fixed a bug in 0.09 that prevented the module from running on some systems.

       Numerous people sent in a patch to fix a bug in 0.10 that broke ping on Windows systems.

       Peter N. Lewis contributed a patch that works correctly on Mac OS X 10.2 (and hopefully other versions as well).

SEE ALSO

       Net::Ping

perl v5.10.1							    2008-12-18							     External(3pm)