[OpenSPARC-T2-DV] / tools / perl-5.8.0 / lib / 5.8.0 / Net / Ping / README

NAME
    Net::Ping - check a remote host for reachability

    $Id: Ping.pm,v 1.6 2002/06/19 15:23:48 rob Exp $

SYNOPSIS
        use Net::Ping;

        $p = Net::Ping->new();
        print "$host is alive.\n" if $p->ping($host);
        $p->close();

        $p = Net::Ping->new("icmp");
        $p->bind($my_addr); # Specify source interface of pings
        foreach $host (@host_array)
        {
            print "$host is ";
            print "NOT " unless $p->ping($host, 2);
            print "reachable.\n";
            sleep(1);
        }
        $p->close();

        $p = Net::Ping->new("tcp", 2);
        # Try connecting to the www port instead of the echo port
        $p->{port_num} = getservbyname("http", "tcp");
        while ($stop_time > time())
        {
            print "$host not reachable ", scalar(localtime()), "\n"
                unless $p->ping($host);
            sleep(300);
        }
        undef($p);

        # High precision syntax (requires Time::HiRes)
        $p = Net::Ping->new();
        $p->hires();
        ($ret, $duration, $ip) = $p->ping($host, 5.5);
        printf("$host [ip: $ip] is alive (packet return time: %.2f ms)\n", 1000 * $duration)
          if $ret;
        $p->close();

        # For backward compatibility
        print "$host is alive.\n" if pingecho($host);

DESCRIPTION
    This module contains methods to test the reachability of remote hosts on
    a network. A ping object is first created with optional parameters, a
    variable number of hosts may be pinged multiple times and then the
    connection is closed.

    You may choose one of four different protocols to use for the ping. The
    "udp" protocol is the default. Note that a live remote host may still
    fail to be pingable by one or more of these protocols. For example,
    www.microsoft.com is generally alive but not pingable.

    With the "tcp" protocol the ping() method attempts to establish a
    connection to the remote host's echo port. If the connection is
    successfully established, the remote host is considered reachable. No
    data is actually echoed. This protocol does not require any special
    privileges but has higher overhead than the other two protocols.

    Specifying the "udp" protocol causes the ping() method to send a udp
    packet to the remote host's echo port. If the echoed packet is received
    from the remote host and the received packet contains the same data as
    the packet that was sent, the remote host is considered reachable. This
    protocol does not require any special privileges. It should be borne in
    mind that, for a udp ping, a host will be reported as unreachable if it
    is not running the appropriate echo service. For Unix-like systems see
    the inetd(8) manpage for more information.

    If the "icmp" protocol is specified, the ping() method sends an icmp
    echo message to the remote host, which is what the UNIX ping program
    does. If the echoed message is received from the remote host and the
    echoed information is correct, the remote host is considered reachable.
    Specifying the "icmp" protocol requires that the program be run as root
    or that the program be setuid to root.

    If the "external" protocol is specified, the ping() method attempts to
    use the `Net::Ping::External' module to ping the remote host.
    `Net::Ping::External' interfaces with your system's default `ping'
    utility to perform the ping, and generally produces relatively accurate
    results. If `Net::Ping::External' if not installed on your system,
    specifying the "external" protocol will result in an error.

  Functions

    Net::Ping->new([$proto [, $def_timeout [, $bytes]]]);
        Create a new ping object. All of the parameters are optional. $proto
        specifies the protocol to use when doing a ping. The current choices
        are "tcp", "udp" or "icmp". The default is "udp".

        If a default timeout ($def_timeout) in seconds is provided, it is
        used when a timeout is not given to the ping() method (below). The
        timeout must be greater than 0 and the default, if not specified, is
        5 seconds.

        If the number of data bytes ($bytes) is given, that many data bytes
        are included in the ping packet sent to the remote host. The number
        of data bytes is ignored if the protocol is "tcp". The minimum (and
        default) number of data bytes is 1 if the protocol is "udp" and 0
        otherwise. The maximum number of data bytes that can be specified is
        1024.

    $p->ping($host [, $timeout]);
        Ping the remote host and wait for a response. $host can be either
        the hostname or the IP number of the remote host. The optional
        timeout must be greater than 0 seconds and defaults to whatever was
        specified when the ping object was created. Returns a success flag.
        If the hostname cannot be found or there is a problem with the IP
        number, the success flag returned will be undef. Otherwise, the
        success flag will be 1 if the host is reachable and 0 if it is not.
        For most practical purposes, undef and 0 and can be treated as the
        same case. In array context, the elapsed time is also returned. The
        elapsed time value will be a float, as retuned by the
        Time::HiRes::time() function, if hires() has been previously called,
        otherwise it is returned as an integer.

    $p->source_verify( { 0 | 1 } );
        Allows source endpoint verification to be enabled or disabled. This
        is useful for those remote destinations with multiples interfaces
        where the response may not originate from the same endpoint that the
        original destination endpoint was sent to. This only affects udp and
        icmp protocol pings.

        This is enabled by default.

    $p->hires( { 0 | 1 } );
        Causes this module to use Time::HiRes module, allowing milliseconds
        to be returned by subsequent calls to ping().

        This is disabled by default.

    $p->bind($local_addr);
        Sets the source address from which pings will be sent. This must be
        the address of one of the interfaces on the local host. $local_addr
        may be specified as a hostname or as a text IP address such as
        "192.168.1.1".

        If the protocol is set to "tcp", this method may be called any
        number of times, and each call to the ping() method (below) will use
        the most recent $local_addr. If the protocol is "icmp" or "udp",
        then bind() must be called at most once per object, and (if it is
        called at all) must be called before the first call to ping() for
        that object.

    $p->open($host);
        When you are using the stream protocol, this call pre-opens the tcp
        socket. It's only necessary to do this if you want to provide a
        different timeout when creating the connection, or remove the
        overhead of establishing the connection from the first ping. If you
        don't call `open()', the connection is automatically opened the
        first time `ping()' is called. This call simply does nothing if you
        are using any protocol other than stream.

    $p->close();
        Close the network connection for this ping object. The network
        connection is also closed by "undef $p". The network connection is
        automatically closed if the ping object goes out of scope (e.g. $p
        is local to a subroutine and you leave the subroutine).

    pingecho($host [, $timeout]);
        To provide backward compatibility with the previous version of
        Net::Ping, a pingecho() subroutine is available with the same
        functionality as before. pingecho() uses the tcp protocol. The
        return values and parameters are the same as described for the
        ping() method. This subroutine is obsolete and may be removed in a
        future version of Net::Ping.

WARNING
    pingecho() or a ping object with the tcp protocol use alarm() to
    implement the timeout. So, don't use alarm() in your program while you
    are using pingecho() or a ping object with the tcp protocol. The udp and
    icmp protocols do not use alarm() to implement the timeout.

NOTES
    There will be less network overhead (and some efficiency in your
    program) if you specify either the udp or the icmp protocol. The tcp
    protocol will generate 2.5 times or more traffic for each ping than
    either udp or icmp. If many hosts are pinged frequently, you may wish to
    implement a small wait (e.g. 25ms or more) between each ping to avoid
    flooding your network with packets.

    The icmp protocol requires that the program be run as root or that it be
    setuid to root. The other protocols do not require special privileges,
    but not all network devices implement tcp or udp echo.

    Local hosts should normally respond to pings within milliseconds.
    However, on a very congested network it may take up to 3 seconds or
    longer to receive an echo packet from the remote host. If the timeout is
    set too low under these conditions, it will appear that the remote host
    is not reachable (which is almost the truth).

    Reachability doesn't necessarily mean that the remote host is actually
    functioning beyond its ability to echo packets. tcp is slightly better
    at indicating the health of a system than icmp because it uses more of
    the networking stack to respond.

    Because of a lack of anything better, this module uses its own routines
    to pack and unpack ICMP packets. It would be better for a separate
    module to be written which understands all of the different kinds of
    ICMP packets.

INSTALL
    The latest source tree is available via cvs:

      cvs -z3 -q -d :pserver:anonymous@cvs.roobik.com.:/usr/local/cvsroot/freeware co Net-Ping
      cd Net-Ping

    The tarball can be created as follows:

      perl Makefile.PL ; make ; make dist

    The latest Net::Ping release can be found at CPAN:

      $CPAN/modules/by-module/Net/

    1) Extract the tarball

      gtar -zxvf Net-Ping-xxxx.tar.gz
      cd Net-Ping-xxxx

    2) Build:

      make realclean
      perl Makefile.PL
      make
      make test

    3) Install

      make install

    Or install it RPM Style:

      rpm -ta SOURCES/Net-Ping-xxxx.tar.gz

      rpm -ih RPMS/noarch/perl-Net-Ping-xxxx.rpm

AUTHORS
      Current maintainer:
        bbb@cpan.org (Rob Brown)

      External protocol:
        colinm@cpan.org (Colin McMillen)

      Stream protocol:
        bronson@trestle.com (Scott Bronson)

      Original pingecho():
        karrer@bernina.ethz.ch (Andreas Karrer)
        pmarquess@bfsec.bt.co.uk (Paul Marquess)

      Original Net::Ping author:
        mose@ns.ccsn.edu (Russell Mosemann)

COPYRIGHT
    Copyright (c) 2002, Rob Brown. All rights reserved.

    Copyright (c) 2001, Colin McMillen. All rights reserved.

    This program is free software; you may redistribute it and/or modify it
    under the same terms as Perl itself.
Commit	Line	Data
86530b38 AT	1	NAME
	2	Net::Ping - check a remote host for reachability
	3
	4	$Id: Ping.pm,v 1.6 2002/06/19 15:23:48 rob Exp $
	5
	6	SYNOPSIS
	7	use Net::Ping;
	8
	9	$p = Net::Ping->new();
	10	print "$host is alive.\n" if $p->ping($host);
	11	$p->close();
	12
	13	$p = Net::Ping->new("icmp");
	14	$p->bind($my_addr); # Specify source interface of pings
	15	foreach $host (@host_array)
	16	{
	17	print "$host is ";
	18	print "NOT " unless $p->ping($host, 2);
	19	print "reachable.\n";
	20	sleep(1);
	21	}
	22	$p->close();
	23
	24	$p = Net::Ping->new("tcp", 2);
	25	# Try connecting to the www port instead of the echo port
	26	$p->{port_num} = getservbyname("http", "tcp");
	27	while ($stop_time > time())
	28	{
	29	print "$host not reachable ", scalar(localtime()), "\n"
	30	unless $p->ping($host);
	31	sleep(300);
	32	}
	33	undef($p);
	34
	35	# High precision syntax (requires Time::HiRes)
	36	$p = Net::Ping->new();
	37	$p->hires();
	38	($ret, $duration, $ip) = $p->ping($host, 5.5);
	39	printf("$host [ip: $ip] is alive (packet return time: %.2f ms)\n", 1000 * $duration)
	40	if $ret;
	41	$p->close();
	42
	43	# For backward compatibility
	44	print "$host is alive.\n" if pingecho($host);
	45
	46	DESCRIPTION
	47	This module contains methods to test the reachability of remote hosts on
	48	a network. A ping object is first created with optional parameters, a
	49	variable number of hosts may be pinged multiple times and then the
	50	connection is closed.
	51
	52	You may choose one of four different protocols to use for the ping. The
	53	"udp" protocol is the default. Note that a live remote host may still
	54	fail to be pingable by one or more of these protocols. For example,
	55	www.microsoft.com is generally alive but not pingable.
	56
	57	With the "tcp" protocol the ping() method attempts to establish a
	58	connection to the remote host's echo port. If the connection is
	59	successfully established, the remote host is considered reachable. No
	60	data is actually echoed. This protocol does not require any special
	61	privileges but has higher overhead than the other two protocols.
	62
	63	Specifying the "udp" protocol causes the ping() method to send a udp
	64	packet to the remote host's echo port. If the echoed packet is received
65	from the remote host and the received packet contains the same data as
66	the packet that was sent, the remote host is considered reachable. This
67	protocol does not require any special privileges. It should be borne in
68	mind that, for a udp ping, a host will be reported as unreachable if it
69	is not running the appropriate echo service. For Unix-like systems see
70	the inetd(8) manpage for more information.
71
72	If the "icmp" protocol is specified, the ping() method sends an icmp
73	echo message to the remote host, which is what the UNIX ping program
74	does. If the echoed message is received from the remote host and the
75	echoed information is correct, the remote host is considered reachable.
76	Specifying the "icmp" protocol requires that the program be run as root
77	or that the program be setuid to root.
78
79	If the "external" protocol is specified, the ping() method attempts to
80	use the `Net::Ping::External' module to ping the remote host.
81	`Net::Ping::External' interfaces with your system's default `ping'
82	utility to perform the ping, and generally produces relatively accurate
83	results. If `Net::Ping::External' if not installed on your system,
84	specifying the "external" protocol will result in an error.
85
86	Functions
87
88	Net::Ping->new([$proto [, $def_timeout [, $bytes]]]);
89	Create a new ping object. All of the parameters are optional. $proto
90	specifies the protocol to use when doing a ping. The current choices
91	are "tcp", "udp" or "icmp". The default is "udp".
92
93	If a default timeout ($def_timeout) in seconds is provided, it is
94	used when a timeout is not given to the ping() method (below). The
95	timeout must be greater than 0 and the default, if not specified, is
96	5 seconds.
97
98	If the number of data bytes ($bytes) is given, that many data bytes
99	are included in the ping packet sent to the remote host. The number
100	of data bytes is ignored if the protocol is "tcp". The minimum (and
101	default) number of data bytes is 1 if the protocol is "udp" and 0
102	otherwise. The maximum number of data bytes that can be specified is
103	1024.
104
105	$p->ping($host [, $timeout]);
106	Ping the remote host and wait for a response. $host can be either
107	the hostname or the IP number of the remote host. The optional
108	timeout must be greater than 0 seconds and defaults to whatever was
109	specified when the ping object was created. Returns a success flag.
110	If the hostname cannot be found or there is a problem with the IP
111	number, the success flag returned will be undef. Otherwise, the
112	success flag will be 1 if the host is reachable and 0 if it is not.
113	For most practical purposes, undef and 0 and can be treated as the
114	same case. In array context, the elapsed time is also returned. The
115	elapsed time value will be a float, as retuned by the
116	Time::HiRes::time() function, if hires() has been previously called,
117	otherwise it is returned as an integer.
118
119	$p->source_verify( { 0 \| 1 } );
120	Allows source endpoint verification to be enabled or disabled. This
121	is useful for those remote destinations with multiples interfaces
122	where the response may not originate from the same endpoint that the
123	original destination endpoint was sent to. This only affects udp and
124	icmp protocol pings.
125
126	This is enabled by default.
127
128	$p->hires( { 0 \| 1 } );
129	Causes this module to use Time::HiRes module, allowing milliseconds
130	to be returned by subsequent calls to ping().
131
132	This is disabled by default.
133
134	$p->bind($local_addr);
135	Sets the source address from which pings will be sent. This must be
136	the address of one of the interfaces on the local host. $local_addr
137	may be specified as a hostname or as a text IP address such as
138	"192.168.1.1".
139
140	If the protocol is set to "tcp", this method may be called any
141	number of times, and each call to the ping() method (below) will use
142	the most recent $local_addr. If the protocol is "icmp" or "udp",
143	then bind() must be called at most once per object, and (if it is
144	called at all) must be called before the first call to ping() for
145	that object.
146
147	$p->open($host);
148	When you are using the stream protocol, this call pre-opens the tcp
149	socket. It's only necessary to do this if you want to provide a
150	different timeout when creating the connection, or remove the
151	overhead of establishing the connection from the first ping. If you
152	don't call `open()', the connection is automatically opened the
153	first time `ping()' is called. This call simply does nothing if you
154	are using any protocol other than stream.
155
156	$p->close();
157	Close the network connection for this ping object. The network
158	connection is also closed by "undef $p". The network connection is
159	automatically closed if the ping object goes out of scope (e.g. $p
160	is local to a subroutine and you leave the subroutine).
161
162	pingecho($host [, $timeout]);
163	To provide backward compatibility with the previous version of
164	Net::Ping, a pingecho() subroutine is available with the same
165	functionality as before. pingecho() uses the tcp protocol. The
166	return values and parameters are the same as described for the
167	ping() method. This subroutine is obsolete and may be removed in a
168	future version of Net::Ping.
169
170	WARNING
171	pingecho() or a ping object with the tcp protocol use alarm() to
172	implement the timeout. So, don't use alarm() in your program while you
173	are using pingecho() or a ping object with the tcp protocol. The udp and
174	icmp protocols do not use alarm() to implement the timeout.
175
176	NOTES
177	There will be less network overhead (and some efficiency in your
178	program) if you specify either the udp or the icmp protocol. The tcp
179	protocol will generate 2.5 times or more traffic for each ping than
180	either udp or icmp. If many hosts are pinged frequently, you may wish to
181	implement a small wait (e.g. 25ms or more) between each ping to avoid
182	flooding your network with packets.
183
184	The icmp protocol requires that the program be run as root or that it be
185	setuid to root. The other protocols do not require special privileges,
186	but not all network devices implement tcp or udp echo.
187
188	Local hosts should normally respond to pings within milliseconds.
189	However, on a very congested network it may take up to 3 seconds or
190	longer to receive an echo packet from the remote host. If the timeout is
191	set too low under these conditions, it will appear that the remote host
192	is not reachable (which is almost the truth).
193
194	Reachability doesn't necessarily mean that the remote host is actually
195	functioning beyond its ability to echo packets. tcp is slightly better
196	at indicating the health of a system than icmp because it uses more of
197	the networking stack to respond.
198
199	Because of a lack of anything better, this module uses its own routines
200	to pack and unpack ICMP packets. It would be better for a separate
201	module to be written which understands all of the different kinds of
202	ICMP packets.
203
204	INSTALL
205	The latest source tree is available via cvs:
206
207	cvs -z3 -q -d :pserver:anonymous@cvs.roobik.com.:/usr/local/cvsroot/freeware co Net-Ping
208	cd Net-Ping
209
210	The tarball can be created as follows:
211
212	perl Makefile.PL ; make ; make dist
213
214	The latest Net::Ping release can be found at CPAN:
215
216	$CPAN/modules/by-module/Net/
217
218	1) Extract the tarball
219
220	gtar -zxvf Net-Ping-xxxx.tar.gz
221	cd Net-Ping-xxxx
222
223	2) Build:
224
225	make realclean
226	perl Makefile.PL
227	make
228	make test
229
230	3) Install
231
232	make install
233
234	Or install it RPM Style:
235
236	rpm -ta SOURCES/Net-Ping-xxxx.tar.gz
237
238	rpm -ih RPMS/noarch/perl-Net-Ping-xxxx.rpm
239
240	AUTHORS
241	Current maintainer:
242	bbb@cpan.org (Rob Brown)
243
244	External protocol:
245	colinm@cpan.org (Colin McMillen)
246
247	Stream protocol:
248	bronson@trestle.com (Scott Bronson)
249
250	Original pingecho():
251	karrer@bernina.ethz.ch (Andreas Karrer)
252	pmarquess@bfsec.bt.co.uk (Paul Marquess)
253
254	Original Net::Ping author:
255	mose@ns.ccsn.edu (Russell Mosemann)
256
257	COPYRIGHT
258	Copyright (c) 2002, Rob Brown. All rights reserved.
259
260	Copyright (c) 2001, Colin McMillen. All rights reserved.
261
262	This program is free software; you may redistribute it and/or modify it
263	under the same terms as Perl itself.
264