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Net::Ping(3pm)         Perl Programmers Reference Guide         Net::Ping(3pm)

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

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
           $p->port_number(getservbyname("http", "tcp"));
           while ($stop_time > time())
           {
               print "$host not reachable ", scalar(localtime()), "\n"
                   unless $p->ping($host);
               sleep(300);
           }
           undef($p);

           # Like tcp protocol, but with many hosts
           $p = Net::Ping->new("syn");
           $p->port_number(getservbyname("http", "tcp"));
           foreach $host (@host_array) {
             $p->ping($host);
           }
           while (($host,$rtt,$ip) = $p->ack) {
             print "HOST: $host [$ip] ACKed in $rtt seconds.\n";
           }

           # 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 six different protocols to use for the ping. The
       "tcp" 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 "icmp" 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 "udp" and "icmp" 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 inetd(8) 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.

       If the "syn" protocol is specified, the ping() method will only send a
       TCP SYN packet to the remote host then immediately return.  If the syn
       packet was sent successfully, it will return a true value, otherwise it
       will return false.  NOTE: Unlike the other protocols, the return value
       does NOT determine if the remote host is alive or not since the full
       TCP three-way handshake may not have completed yet.  The remote host is
       only considered reachable if it receives a TCP ACK within the timeout
       specified.  To begin waiting for the ACK packets, use the ack() method
       as explained below.  Use the "syn" protocol instead the "tcp" protocol
       to determine reachability of multiple destinations simultaneously by
       sending parallel TCP SYN packets.  It will not block while testing each
       remote host.  demo/fping is provided in this distribution to
       demonstrate the "syn" protocol as an example.  This protocol does not
       require any special privileges.

   Functions
       Net::Ping->new([$proto [, $def_timeout [, $bytes [, $device [, $tos
       ]]]]]);
           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", "icmp", "stream", "syn", or
           "external".  The default is "tcp".

           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.

           If $device is given, this device is used to bind the source
           endpoint before sending the ping packet.  I believe this only works
           with superuser privileges and with udp and icmp protocols at this
           time.

           If $tos is given, this ToS is configured into the socket.

       $p->ping($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 as well as
           the string form of the ip the host resolved to are 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->service_check( { 0 | 1 } );
           Set whether or not the connect behavior should enforce remote
           service availability as well as reachability.  Normally, if the
           remote server reported ECONNREFUSED, it must have been reachable
           because of the status packet that it reported.  With this option
           enabled, the full three-way tcp handshake must have been
           established successfully before it will claim it is reachable.
           NOTE:  It still does nothing more than connect and disconnect.  It
           does not speak any protocol (i.e., HTTP or FTP) to ensure the
           remote server is sane in any way.  The remote server CPU could be
           grinding to a halt and unresponsive to any clients connecting, but
           if the kernel throws the ACK packet, it is considered alive anyway.
           To really determine if the server is responding well would be
           application specific and is beyond the scope of Net::Ping.  For udp
           protocol, enabling this option demands that the remote server
           replies with the same udp data that it was sent as defined by the
           udp echo service.

           This affects the "udp", "tcp", and "syn" protocols.

           This is disabled by default.

       $p->tcp_service_check( { 0 | 1 } );
           Deprecated method, but does the same as service_check() method.

       $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->ack( [ $host ] );
           When using the "syn" protocol, use this method to determine the
           reachability of the remote host.  This method is meant to be called
           up to as many times as ping() was called.  Each call returns the
           host (as passed to ping()) that came back with the TCP ACK.  The
           order in which the hosts are returned may not necessarily be the
           same order in which they were SYN queued using the ping() method.
           If the timeout is reached before the TCP ACK is received, or if the
           remote host is not listening on the port attempted, then the TCP
           connection will not be established and ack() will return undef.  In
           list context, the host, the ack time, and the dotted ip string will
           be returned instead of just the host.  If the optional $host
           argument is specified, the return value will be pertaining to that
           host only.  This call simply does nothing if you are using any
           protocol other than syn.

       $p->nack( $failed_ack_host );
           The reason that host $failed_ack_host did not receive a valid ACK.
           Useful to find out why when ack( $fail_ack_host ) returns a false
           value.

       $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).

       $p->port_number([$port_number])
           When called with a port number, the port number used to ping is set
           to $port_number rather than using the echo port.  It also has the
           effect of calling "$p->service_check(1)" causing a ping to return a
           successful response only if that specific port is accessible.  This
           function returns the value of the port that "ping()" will connect
           to.

       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.

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 checkout 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

BUGS
       For a list of known issues, visit:

       https://rt.cpan.org/NoAuth/Bugs.html?Dist=Net-Ping

       To report a new bug, visit:

       https://rt.cpan.org/NoAuth/ReportBug.html?Queue=Net-Ping

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) 2002-2003, 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.

       $Id: Ping.pm,v 1.86 2003/06/27 21:31:07 rob Exp $

perl v5.12.1                      2010-04-26                    Net::Ping(3pm)
 

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Gedruckt am: 20.11.2017 16:38 GMT+0100 (2017-11-20T16:38:28+01:00)