1Net::Ping(3pm) Perl Programmers Reference Guide Net::Ping(3pm)
2
6 Net::Ping - check a remote host for reachability
7
9 use Net::Ping;
10 $p = Net::Ping->new();
12 print "$host is alive.\n" if $p->ping($host);
13 $p->close();
14 $p = Net::Ping->new("icmp");
16 $p->bind($my_addr); # Specify source interface of pings
17 foreach $host (@host_array)
18 {
19 print "$host is ";
20 print "NOT " unless $p->ping($host, 2);
21 print "reachable.\n";
22 sleep(1);
23 }
24 $p->close();
25 $p = Net::Ping->new("tcp", 2);
27 # Try connecting to the www port instead of the echo port
28 $p->port_number(scalar(getservbyname("http", "tcp")));
29 while ($stop_time > time())
30 {
31 print "$host not reachable ", scalar(localtime()), "\n"
32 unless $p->ping($host);
33 sleep(300);
34 }
35 undef($p);
36 # Like tcp protocol, but with many hosts
38 $p = Net::Ping->new("syn");
39 $p->port_number(getservbyname("http", "tcp"));
40 foreach $host (@host_array) {
41 $p->ping($host);
42 }
43 while (($host,$rtt,$ip) = $p->ack) {
44 print "HOST: $host [$ip] ACKed in $rtt seconds.\n";
45 }
46 # High precision syntax (requires Time::HiRes)
48 $p = Net::Ping->new();
49 $p->hires();
50 ($ret, $duration, $ip) = $p->ping($host, 5.5);
51 printf("$host [ip: $ip] is alive (packet return time: %.2f ms)\n",
52 1000 * $duration)
53 if $ret;
54 $p->close();
55 # For backward compatibility
57 print "$host is alive.\n" if pingecho($host);
58
60 This module contains methods to test the reachability of remote hosts
61 on a network. A ping object is first created with optional parameters,
62 a variable number of hosts may be pinged multiple times and then the
63 connection is closed.
64 You may choose one of six different protocols to use for the ping. The
66 "tcp" protocol is the default. Note that a live remote host may still
67 fail to be pingable by one or more of these protocols. For example,
68 www.microsoft.com is generally alive but not "icmp" pingable.
69 With the "tcp" protocol the ping() method attempts to establish a
71 connection to the remote host's echo port. If the connection is
72 successfully established, the remote host is considered reachable. No
73 data is actually echoed. This protocol does not require any special
74 privileges but has higher overhead than the "udp" and "icmp" protocols.
75 Specifying the "udp" protocol causes the ping() method to send a udp
77 packet to the remote host's echo port. If the echoed packet is
78 received from the remote host and the received packet contains the same
79 data as the packet that was sent, the remote host is considered
80 reachable. This protocol does not require any special privileges. It
81 should be borne in mind that, for a udp ping, a host will be reported
82 as unreachable if it is not running the appropriate echo service. For
83 Unix-like systems see inetd(8) for more information.
84 If the "icmp" protocol is specified, the ping() method sends an icmp
86 echo message to the remote host, which is what the UNIX ping program
87 does. If the echoed message is received from the remote host and the
88 echoed information is correct, the remote host is considered reachable.
89 Specifying the "icmp" protocol requires that the program be run as root
90 or that the program be setuid to root.
91 If the "external" protocol is specified, the ping() method attempts to
93 use the "Net::Ping::External" module to ping the remote host.
94 "Net::Ping::External" interfaces with your system's default "ping"
95 utility to perform the ping, and generally produces relatively accurate
96 results. If "Net::Ping::External" if not installed on your system,
97 specifying the "external" protocol will result in an error.
98 If the "syn" protocol is specified, the "ping" method will only send a
100 TCP SYN packet to the remote host then immediately return. If the syn
101 packet was sent successfully, it will return a true value, otherwise it
102 will return false. NOTE: Unlike the other protocols, the return value
103 does NOT determine if the remote host is alive or not since the full
104 TCP three-way handshake may not have completed yet. The remote host is
105 only considered reachable if it receives a TCP ACK within the timeout
106 specified. To begin waiting for the ACK packets, use the "ack" method
107 as explained below. Use the "syn" protocol instead the "tcp" protocol
108 to determine reachability of multiple destinations simultaneously by
109 sending parallel TCP SYN packets. It will not block while testing each
110 remote host. This protocol does not require any special privileges.
111 Functions
113 Net::Ping->new([proto, timeout, bytes, device, tos, ttl, family, host,
114 port, bind, gateway, retrans, pingstring, source_verify econnrefused
115 dontfrag IPV6_USE_MIN_MTU IPV6_RECVPATHMTU])
116 Create a new ping object. All of the parameters are optional and
117 can be passed as hash ref. All options besides the first 7 must be
118 passed as hash ref.
119 "proto" specifies the protocol to use when doing a ping. The
121 current choices are "tcp", "udp", "icmp", "icmpv6", "stream",
122 "syn", or "external". The default is "tcp".
123 If a "timeout" in seconds is provided, it is used when a timeout is
125 not given to the ping() method (below). The timeout must be
126 greater than 0 and the default, if not specified, is 5 seconds.
127 If the number of data bytes ("bytes") is given, that many data
129 bytes are included in the ping packet sent to the remote host. The
130 number of data bytes is ignored if the protocol is "tcp". The
131 minimum (and default) number of data bytes is 1 if the protocol is
132 "udp" and 0 otherwise. The maximum number of data bytes that can
133 be specified is 65535, but staying below the MTU (1472 bytes for
134 ICMP) is recommended. Many small devices cannot deal with
135 fragmented ICMP packets.
136 If "device" is given, this device is used to bind the source
138 endpoint before sending the ping packet. I believe this only works
139 with superuser privileges and with udp and icmp protocols at this
140 time.
141 If <tos> is given, this ToS is configured into the socket.
143 For icmp, "ttl" can be specified to set the TTL of the outgoing
145 packet.
146 Valid "family" values for IPv4:
148 4, v4, ip4, ipv4, AF_INET (constant)
150 Valid "family" values for IPv6:
152 6, v6, ip6, ipv6, AF_INET6 (constant)
154 The "host" argument implicitly specifies the family if the family
156 argument is not given.
157 The "port" argument is only valid for a udp, tcp or stream ping,
159 and will not do what you think it does. ping returns true when we
160 get a "Connection refused"! The default is the echo port.
161 The "bind" argument specifies the local_addr to bind to. By
163 specifying a bind argument you don't need the bind method.
164 The "gateway" argument is only valid for IPv6, and requires a IPv6
166 address.
167 The "retrans" argument the exponential backoff rate, default 1.2.
169 It matches the $def_factor global.
170 The "dontfrag" argument sets the IP_DONTFRAG bit, but note that
172 IP_DONTFRAG is not yet defined by Socket, and not available on many
173 systems. Then it is ignored. On linux it also sets IP_MTU_DISCOVER
174 to IP_PMTUDISC_DO but need we don't chunk oversized packets. You
175 need to set $data_size manually.
176 $p->ping($host [, $timeout [, $family]]);
178 Ping the remote host and wait for a response. $host can be either
179 the hostname or the IP number of the remote host. The optional
180 timeout must be greater than 0 seconds and defaults to whatever was
181 specified when the ping object was created. Returns a success
182 flag. If the hostname cannot be found or there is a problem with
183 the IP number, the success flag returned will be undef. Otherwise,
184 the success flag will be 1 if the host is reachable and 0 if it is
185 not. For most practical purposes, undef and 0 and can be treated
186 as the same case. In array context, the elapsed time as well as
187 the string form of the ip the host resolved to are also returned.
188 The elapsed time value will be a float, as returned by the
189 Time::HiRes::time() function, if hires() has been previously
190 called, otherwise it is returned as an integer.
191 $p->source_verify( { 0 | 1 } );
193 Allows source endpoint verification to be enabled or disabled.
194 This is useful for those remote destinations with multiples
195 interfaces where the response may not originate from the same
196 endpoint that the original destination endpoint was sent to. This
197 only affects udp and icmp protocol pings.
198 This is enabled by default.
200 $p->service_check( { 0 | 1 } );
202 Set whether or not the connect behavior should enforce remote
203 service availability as well as reachability. Normally, if the
204 remote server reported ECONNREFUSED, it must have been reachable
205 because of the status packet that it reported. With this option
206 enabled, the full three-way tcp handshake must have been
207 established successfully before it will claim it is reachable.
208 NOTE: It still does nothing more than connect and disconnect. It
209 does not speak any protocol (i.e., HTTP or FTP) to ensure the
210 remote server is sane in any way. The remote server CPU could be
211 grinding to a halt and unresponsive to any clients connecting, but
212 if the kernel throws the ACK packet, it is considered alive anyway.
213 To really determine if the server is responding well would be
214 application specific and is beyond the scope of Net::Ping. For udp
215 protocol, enabling this option demands that the remote server
216 replies with the same udp data that it was sent as defined by the
217 udp echo service.
218 This affects the "udp", "tcp", and "syn" protocols.
220 This is disabled by default.
222 $p->tcp_service_check( { 0 | 1 } );
224 Deprecated method, but does the same as service_check() method.
225 $p->hires( { 0 | 1 } );
227 With 1 causes this module to use Time::HiRes module, allowing
228 milliseconds to be returned by subsequent calls to ping().
229 $p->time
231 The current time, hires or not.
232 $p->socket_blocking_mode( $fh, $mode );
234 Sets or clears the O_NONBLOCK flag on a file handle.
235 $p->IPV6_USE_MIN_MTU
237 With argument sets the option. Without returns the option value.
238 $p->IPV6_RECVPATHMTU
240 Notify an according IPv6 MTU.
241 With argument sets the option. Without returns the option value.
243 $p->IPV6_HOPLIMIT
245 With argument sets the option. Without returns the option value.
246 $p->IPV6_REACHCONF NYI
248 Sets ipv6 reachability IPV6_REACHCONF was removed in RFC3542. ping6
249 -R supports it. IPV6_REACHCONF requires root/admin permissions.
250 With argument sets the option. Without returns the option value.
252 Not yet implemented.
254 $p->bind($local_addr);
256 Sets the source address from which pings will be sent. This must
257 be the address of one of the interfaces on the local host.
258 $local_addr may be specified as a hostname or as a text IP address
259 such as "192.168.1.1".
260 If the protocol is set to "tcp", this method may be called any
262 number of times, and each call to the ping() method (below) will
263 use the most recent $local_addr. If the protocol is "icmp" or
264 "udp", then bind() must be called at most once per object, and (if
265 it is called at all) must be called before the first call to ping()
266 for that object.
267 The bind() call can be omitted when specifying the "bind" option to
269 new().
270 $p->message_type([$ping_type]);
272 When you are using the "icmp" protocol, this call permit to change
273 the message type to 'echo' or 'timestamp' (only for IPv4, see RFC
274 792).
275 Without argument, it returns the currently used icmp protocol
277 message type. By default, it returns 'echo'.
278 $p->open($host);
280 When you are using the "stream" protocol, this call pre-opens the
281 tcp socket. It's only necessary to do this if you want to provide
282 a different timeout when creating the connection, or remove the
283 overhead of establishing the connection from the first ping. If
284 you don't call "open()", the connection is automatically opened the
285 first time "ping()" is called. This call simply does nothing if
286 you are using any protocol other than stream.
287 The $host argument can be omitted when specifying the "host" option
289 to new().
290 $p->ack( [ $host ] );
292 When using the "syn" protocol, use this method to determine the
293 reachability of the remote host. This method is meant to be called
294 up to as many times as ping() was called. Each call returns the
295 host (as passed to ping()) that came back with the TCP ACK. The
296 order in which the hosts are returned may not necessarily be the
297 same order in which they were SYN queued using the ping() method.
298 If the timeout is reached before the TCP ACK is received, or if the
299 remote host is not listening on the port attempted, then the TCP
300 connection will not be established and ack() will return undef. In
301 list context, the host, the ack time, the dotted ip string, and the
302 port number will be returned instead of just the host. If the
303 optional $host argument is specified, the return value will be
304 pertaining to that host only. This call simply does nothing if you
305 are using any protocol other than "syn".
306 When "new" had a host option, this host will be used. Without
308 $host argument, all hosts are scanned.
309 $p->nack( $failed_ack_host );
311 The reason that "host $failed_ack_host" did not receive a valid
312 ACK. Useful to find out why when "ack($fail_ack_host)" returns a
313 false value.
314 $p->ack_unfork($host)
316 The variant called by "ack" with the "syn" protocol and
317 $syn_forking enabled.
318 $p->ping_icmp([$host, $timeout, $family])
320 The "ping" method used with the icmp protocol.
321 $p->ping_icmpv6([$host, $timeout, $family]) NYI
323 The "ping" method used with the icmpv6 protocol.
324 $p->ping_stream([$host, $timeout, $family])
326 The "ping" method used with the stream protocol.
327 Perform a stream ping. If the tcp connection isn't already open,
329 it opens it. It then sends some data and waits for a reply. It
330 leaves the stream open on exit.
331 $p->ping_syn([$host, $ip, $start_time, $stop_time])
333 The "ping" method used with the syn protocol. Sends a TCP SYN
334 packet to host specified.
335 $p->ping_syn_fork([$host, $timeout, $family])
337 The "ping" method used with the forking syn protocol.
338 $p->ping_tcp([$host, $timeout, $family])
340 The "ping" method used with the tcp protocol.
341 $p->ping_udp([$host, $timeout, $family])
343 The "ping" method used with the udp protocol.
344 Perform a udp echo ping. Construct a message of at least the one-
346 byte sequence number and any additional data bytes. Send the
347 message out and wait for a message to come back. If we get a
348 message, make sure all of its parts match. If they do, we are
349 done. Otherwise go back and wait for the message until we run out
350 of time. Return the result of our efforts.
351 $p->ping_external([$host, $timeout, $family])
353 The "ping" method used with the external protocol. Uses
354 Net::Ping::External to do an external ping.
355 $p->tcp_connect([$ip, $timeout])
357 Initiates a TCP connection, for a tcp ping.
358 $p->tcp_echo([$ip, $timeout, $pingstring])
360 Performs a TCP echo. It writes the given string to the socket and
361 then reads it back. It returns 1 on success, 0 on failure.
362 $p->close();
364 Close the network connection for this ping object. The network
365 connection is also closed by "undef $p". The network connection is
366 automatically closed if the ping object goes out of scope (e.g. $p
367 is local to a subroutine and you leave the subroutine).
368 $p->port_number([$port_number])
370 When called with a port number, the port number used to ping is set
371 to $port_number rather than using the echo port. It also has the
372 effect of calling "$p->service_check(1)" causing a ping to return a
373 successful response only if that specific port is accessible. This
374 function returns the value of the port that "ping" will connect to.
375 $p->mselect
377 A "select()" wrapper that compensates for platform peculiarities.
378 $p->ntop
380 Platform abstraction over "inet_ntop()"
381 $p->checksum($msg)
383 Do a checksum on the message. Basically sum all of the short words
384 and fold the high order bits into the low order bits.
385 $p->icmp_result
387 Returns a list of addr, type, subcode.
388 pingecho($host [, $timeout]);
390 To provide backward compatibility with the previous version of
391 Net::Ping, a "pingecho()" subroutine is available with the same
392 functionality as before. "pingecho()" uses the tcp protocol. The
393 return values and parameters are the same as described for the
394 "ping" method. This subroutine is obsolete and may be removed in a
395 future version of Net::Ping.
396 wakeonlan($mac, [$host, [$port]])
398 Emit the popular wake-on-lan magic udp packet to wake up a local
399 device. See also Net::Wake, but this has the mac address as 1st
400 arg. $host should be the local gateway. Without it will broadcast.
401 Default host: '255.255.255.255' Default port: 9
403 perl -MNet::Ping=wakeonlan -e'wakeonlan "e0:69:95:35:68:d2"'
405
407 There will be less network overhead (and some efficiency in your
408 program) if you specify either the udp or the icmp protocol. The tcp
409 protocol will generate 2.5 times or more traffic for each ping than
410 either udp or icmp. If many hosts are pinged frequently, you may wish
411 to implement a small wait (e.g. 25ms or more) between each ping to
412 avoid flooding your network with packets.
413 The icmp and icmpv6 protocols requires that the program be run as root
415 or that it be setuid to root. The other protocols do not require
416 special privileges, but not all network devices implement tcp or udp
417 echo.
418 Local hosts should normally respond to pings within milliseconds.
420 However, on a very congested network it may take up to 3 seconds or
421 longer to receive an echo packet from the remote host. If the timeout
422 is set too low under these conditions, it will appear that the remote
423 host is not reachable (which is almost the truth).
424 Reachability doesn't necessarily mean that the remote host is actually
426 functioning beyond its ability to echo packets. tcp is slightly better
427 at indicating the health of a system than icmp because it uses more of
428 the networking stack to respond.
429 Because of a lack of anything better, this module uses its own routines
431 to pack and unpack ICMP packets. It would be better for a separate
432 module to be written which understands all of the different kinds of
433 ICMP packets.
434
436 The latest source tree is available via git:
437 git clone https://github.com/rurban/Net-Ping.git
439 cd Net-Ping
440 The tarball can be created as follows:
442 perl Makefile.PL ; make ; make dist
444 The latest Net::Ping releases are included in cperl and perl5.
446
448 For a list of known issues, visit:
449 <https://rt.cpan.org/NoAuth/Bugs.html?Dist=Net-Ping> and
451 <https://github.com/rurban/Net-Ping/issues>
452 To report a new bug, visit:
454 <https://github.com/rurban/Net-Ping/issues>
456
458 Current maintainers:
459 perl11 (for cperl, with IPv6 support and more)
460 p5p (for perl5)
461 Previous maintainers:
463 bbb@cpan.org (Rob Brown)
464 Steve Peters
465 External protocol:
467 colinm@cpan.org (Colin McMillen)
468 Stream protocol:
470 bronson@trestle.com (Scott Bronson)
471 Wake-on-lan:
473 1999-2003 Clinton Wong
474 Original pingecho():
476 karrer@bernina.ethz.ch (Andreas Karrer)
477 pmarquess@bfsec.bt.co.uk (Paul Marquess)
478 Original Net::Ping author:
480 mose@ns.ccsn.edu (Russell Mosemann)
481
483 Copyright (c) 2017-2018, Reini Urban. All rights reserved.
484 Copyright (c) 2016, cPanel Inc. All rights reserved.
486 Copyright (c) 2012, Steve Peters. All rights reserved.
488 Copyright (c) 2002-2003, Rob Brown. All rights reserved.
490 Copyright (c) 2001, Colin McMillen. All rights reserved.
492 This program is free software; you may redistribute it and/or modify it
494 under the same terms as Perl itself.
495perl v5.30.2 2020-03-27 Net::Ping(3pm)