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

       Net::Ping - check a remote host for reachability

           use Net::Ping;

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

           $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";

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

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

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

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

       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"

       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.

       Net::Ping->new([$proto [, $def_timeout [, $bytes [, $device [, $tos [, $ttl ]]]]]]);
           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.

           For icmp, $ttl can be specified to set the TTL of the outgoing packet.

       $p->ping($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 returned 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.

           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 "".

           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

           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.

           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

           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

       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.

       The latest source tree is available via cvs:

         cvs -z3 -q -d \
           :pserver:anonymous AT cvs.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:


       1) Extract the tarball

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

       2) Build:

         make realclean
         perl Makefile.PL
         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

       For a list of known issues, visit:


       To report a new bug, visit:


         Current maintainer:
           bbb AT cpan.org (Rob Brown)

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

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

         Original pingecho():
           karrer AT bernina.ch (Andreas Karrer)
           pmarquess AT bfsec.uk (Paul Marquess)

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

       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.

perl v5.20.2                                2018-06-10                           Net::Ping(3perl)

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