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

Net::Ping(3p) Perl Programmers Reference Guide Net::Ping(3p) #

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

NNAAMMEE #

 Net::Ping - check a remote host for reachability

SSYYNNOOPPSSIISS #

     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("icmpv6");
     $ip = "[fd00:dead:beef::4e]";
     print "$ip is alive.\n" if $p->ping($ip);

     $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);
         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);

DDEESSCCRRIIPPTTIIOONN #

 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 ppiinngg(()) 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 ppiinngg(()) 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
 iinneettdd(8) for more information.

 If the "icmp" protocol is specified, the ppiinngg(()) 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 ppiinngg(()) 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.  This protocol does not require any special privileges.

FFuunnccttiioonnss Net::Ping->new([proto, timeout, bytes, device, tos, ttl, family, host, port, bind, gateway, retrans, pingstring, source_verify econnrefused dontfrag IPV6_USE_MIN_MTU IPV6_RECVPATHMTU]) Create a new ping object. All of the parameters are optional and can be passed as hash ref. All options besides the first 7 must be passed as hash ref.

     "proto" specifies the protocol to use when doing a ping.  The current
     choices are "tcp", "udp", "icmp", "icmpv6", "stream", "syn", or
     "external".  The default is "tcp".

     If a "timeout" in seconds is provided, it is used when a timeout is
     not given to the ppiinngg(()) 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
     65535, but staying below the MTU (1472 bytes for ICMP) is
     recommended.  Many small devices cannot deal with fragmented ICMP
     packets.

     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.

     Valid "family" values for IPv4:

        4, v4, ip4, ipv4, AF_INET (constant)

     Valid "family" values for IPv6:

        6, v6, ip6, ipv6, AF_INET6 (constant)

     The "host" argument implicitly specifies the family if the family
     argument is not given.

     The "port" argument is only valid for a udp, tcp or stream ping, and
     will not do what you think it does. ping returns true when we get a
     "Connection refused"!  The default is the echo port.

     The "bind" argument specifies the local_addr to bind to.  By
     specifying a bind argument you don't need the bind method.

     The "gateway" argument is only valid for IPv6, and requires a IPv6
     address.

     The "retrans" argument the exponential backoff rate, default 1.2.  It
     matches the $def_factor global.

     The "dontfrag" argument sets the IP_DONTFRAG bit, but note that
     IP_DONTFRAG is not yet defined by Socket, and not available on many
     systems. Then it is ignored. On linux it also sets IP_MTU_DISCOVER to
     IP_PMTUDISC_DO but need we don't chunk oversized packets. You need to
     set $data_size manually.

 $p->ping($host [, $timeout [, $family]]);
     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 TTiimmee::::HHiiRReess::::ttiimmee(())
     function, if hhiirreess(()) 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 sseerrvviiccee__cchheecckk(()) method.

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

 $p->time
     The current time, hires or not.

 $p->socket_blocking_mode( $fh, $mode );
     Sets or clears the O_NONBLOCK flag on a file handle.

 $p->IPV6_USE_MIN_MTU
     With argument sets the option.  Without returns the option value.

 $p->IPV6_RECVPATHMTU
     Notify an according IPv6 MTU.

     With argument sets the option.  Without returns the option value.

 $p->IPV6_HOPLIMIT
     With argument sets the option.  Without returns the option value.

 $p->IPV6_REACHCONF _N_Y_I
     Sets ipv6 reachability IPV6_REACHCONF was removed in RFC3542. ping6
     -R supports it.  IPV6_REACHCONF requires root/admin permissions.

     With argument sets the option.  Without returns the option value.

     Not yet implemented.

 $p->bind($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 ppiinngg(()) method (below) will use the
     most recent $local_addr.  If the protocol is "icmp" or "udp", then
     bbiinndd(()) must be called at most once per object, and (if it is called
     at all) must be called before the first call to ppiinngg(()) for that
     object.

     The bbiinndd(()) call can be omitted when specifying the "bind" option to
     nneeww(()).

 $p->message_type([$ping_type]);
     When you are using the "icmp" protocol, this call permit to change
     the message type to 'echo' or 'timestamp' (only for IPv4, see RFC
     792).

     Without argument, it returns the currently used icmp protocol message
     type.  By default, it returns 'echo'.

 $p->open($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.

     The $host argument can be omitted when specifying the "host" option
     to nneeww(()).

 $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 ppiinngg(()) was called.  Each call returns the host
     (as passed to ppiinngg(())) 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 ppiinngg(()) 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 aacckk(()) will return undef.  In list context, the
     host, the ack time, the dotted ip string, and the port number 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".

     When "new" had a host option, this host will be used.  Without $host
     argument, all hosts are scanned.

 $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.

 $p->ack_unfork($host)
     The variant called by "ack" with the "syn" protocol and $syn_forking
     enabled.

 $p->ping_icmp([$host, $timeout, $family])
     The "ping" method used with the icmp protocol.

 $p->ping_icmpv6([$host, $timeout, $family])
     The "ping" method used with the icmpv6 protocol.

 $p->ping_stream([$host, $timeout, $family])
     The "ping" method used with the stream protocol.

     Perform a stream ping.  If the tcp connection isn't already open, it
     opens it.  It then sends some data and waits for a reply.  It leaves
     the stream open on exit.

 $p->ping_syn([$host, $ip, $start_time, $stop_time])
     The "ping" method used with the syn protocol.  Sends a TCP SYN packet
     to host specified.

 $p->ping_syn_fork([$host, $timeout, $family])
     The "ping" method used with the forking syn protocol.

 $p->ping_tcp([$host, $timeout, $family])
     The "ping" method used with the tcp protocol.

 $p->ping_udp([$host, $timeout, $family])
     The "ping" method used with the udp protocol.

     Perform a udp echo ping.  Construct a message of at least the one-
     byte sequence number and any additional data bytes.  Send the message
     out and wait for a message to come back.  If we get a message, make
     sure all of its parts match.  If they do, we are done.  Otherwise go
     back and wait for the message until we run out of time.  Return the
     result of our efforts.

 $p->ping_external([$host, $timeout, $family])
     The "ping" method used with the external protocol.  Uses
     Net::Ping::External to do an external ping.

 $p->tcp_connect([$ip, $timeout])
     Initiates a TCP connection, for a tcp ping.

 $p->tcp_echo([$ip, $timeout, $pingstring])
     Performs a TCP echo.  It writes the given string to the socket and
     then reads it back.  It returns 1 on success, 0 on failure.

 $p->cclloossee(());
     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.

 $p->mselect
     A "select()" wrapper that compensates for platform peculiarities.

 $p->ntop
     Platform abstraction over "inet_ntop()"

 $p->checksum($msg)
     Do a checksum on the message.  Basically sum all of the short words
     and fold the high order bits into the low order bits.

 $p->icmp_result
     Returns a list of addr, type, subcode.

 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.

 wakeonlan($mac, [$host, [$port]])
     Emit the popular wake-on-lan magic udp packet to wake up a local
     device.  See also Net::Wake, but this has the mac address as 1st arg.
     $host should be the local gateway. Without it will broadcast.

     Default host: '255.255.255.255' Default port: 9

       perl -MNet::Ping=wakeonlan -e'wakeonlan "e0:69:95:35:68:d2"'

NNOOTTEESS #

 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 and icmpv6 protocols 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.

IINNSSTTAALLLL #

 The latest source tree is available via git:

   git clone https://github.com/rurban/Net-Ping.git
   cd Net-Ping

 The tarball can be created as follows:

   perl Makefile.PL ; make ; make dist

 The latest Net::Ping releases are included in cperl and perl5.

BBUUGGSS #

 For a list of known issues, visit:

 <https://rt.cpan.org/NoAuth/Bugs.html?Dist=Net-Ping> and
 <https://github.com/rurban/Net-Ping/issues>

 To report a new bug, visit:

 <https://github.com/rurban/Net-Ping/issues>

AAUUTTHHOORRSS #

   Current maintainers:
     perl11 (for cperl, with IPv6 support and more)
     p5p    (for perl5)

   Previous maintainers:
     bbb@cpan.org (Rob Brown)
     Steve Peters

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

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

   Wake-on-lan:
     1999-2003 Clinton Wong

   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)

CCOOPPYYRRIIGGHHTT #

 Copyright (c) 2017-2020, Reini Urban.  All rights reserved.

 Copyright (c) 2016, cPanel Inc.  All rights reserved.

 Copyright (c) 2012, Steve Peters.  All rights reserved.

 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 v5.36.3 2023-02-15 Net::Ping(3p)