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129 | .\" ======================================================================== | |
130 | .\" | |
131 | .IX Title "Net::Ping 3" | |
132 | .TH Net::Ping 3 "2001-09-21" "perl v5.8.8" "Perl Programmers Reference Guide" | |
133 | .SH "NAME" | |
134 | Net::Ping \- check a remote host for reachability | |
135 | .SH "SYNOPSIS" | |
136 | .IX Header "SYNOPSIS" | |
137 | .Vb 1 | |
138 | \& use Net::Ping; | |
139 | .Ve | |
140 | .PP | |
141 | .Vb 3 | |
142 | \& $p = Net::Ping->new(); | |
143 | \& print "$host is alive.\en" if $p->ping($host); | |
144 | \& $p->close(); | |
145 | .Ve | |
146 | .PP | |
147 | .Vb 10 | |
148 | \& $p = Net::Ping->new("icmp"); | |
149 | \& $p->bind($my_addr); # Specify source interface of pings | |
150 | \& foreach $host (@host_array) | |
151 | \& { | |
152 | \& print "$host is "; | |
153 | \& print "NOT " unless $p->ping($host, 2); | |
154 | \& print "reachable.\en"; | |
155 | \& sleep(1); | |
156 | \& } | |
157 | \& $p->close(); | |
158 | .Ve | |
159 | .PP | |
160 | .Vb 10 | |
161 | \& $p = Net::Ping->new("tcp", 2); | |
162 | \& # Try connecting to the www port instead of the echo port | |
163 | \& $p->{port_num} = getservbyname("http", "tcp"); | |
164 | \& while ($stop_time > time()) | |
165 | \& { | |
166 | \& print "$host not reachable ", scalar(localtime()), "\en" | |
167 | \& unless $p->ping($host); | |
168 | \& sleep(300); | |
169 | \& } | |
170 | \& undef($p); | |
171 | .Ve | |
172 | .PP | |
173 | .Vb 9 | |
174 | \& # Like tcp protocol, but with many hosts | |
175 | \& $p = Net::Ping->new("syn"); | |
176 | \& $p->{port_num} = getservbyname("http", "tcp"); | |
177 | \& foreach $host (@host_array) { | |
178 | \& $p->ping($host); | |
179 | \& } | |
180 | \& while (($host,$rtt,$ip) = $p->ack) { | |
181 | \& print "HOST: $host [$ip] ACKed in $rtt seconds.\en"; | |
182 | \& } | |
183 | .Ve | |
184 | .PP | |
185 | .Vb 7 | |
186 | \& # High precision syntax (requires Time::HiRes) | |
187 | \& $p = Net::Ping->new(); | |
188 | \& $p->hires(); | |
189 | \& ($ret, $duration, $ip) = $p->ping($host, 5.5); | |
190 | \& printf("$host [ip: $ip] is alive (packet return time: %.2f ms)\en", 1000 * $duration) | |
191 | \& if $ret; | |
192 | \& $p->close(); | |
193 | .Ve | |
194 | .PP | |
195 | .Vb 2 | |
196 | \& # For backward compatibility | |
197 | \& print "$host is alive.\en" if pingecho($host); | |
198 | .Ve | |
199 | .SH "DESCRIPTION" | |
200 | .IX Header "DESCRIPTION" | |
201 | This module contains methods to test the reachability of remote | |
202 | hosts on a network. A ping object is first created with optional | |
203 | parameters, a variable number of hosts may be pinged multiple | |
204 | times and then the connection is closed. | |
205 | .PP | |
206 | You may choose one of six different protocols to use for the | |
207 | ping. The \*(L"tcp\*(R" protocol is the default. Note that a live remote host | |
208 | may still fail to be pingable by one or more of these protocols. For | |
209 | example, www.microsoft.com is generally alive but not \*(L"icmp\*(R" pingable. | |
210 | .PP | |
211 | With the \*(L"tcp\*(R" protocol the \fIping()\fR method attempts to establish a | |
212 | connection to the remote host's echo port. If the connection is | |
213 | successfully established, the remote host is considered reachable. No | |
214 | data is actually echoed. This protocol does not require any special | |
215 | privileges but has higher overhead than the \*(L"udp\*(R" and \*(L"icmp\*(R" protocols. | |
216 | .PP | |
217 | Specifying the \*(L"udp\*(R" protocol causes the \fIping()\fR method to send a udp | |
218 | packet to the remote host's echo port. If the echoed packet is | |
219 | received from the remote host and the received packet contains the | |
220 | same data as the packet that was sent, the remote host is considered | |
221 | reachable. This protocol does not require any special privileges. | |
222 | It should be borne in mind that, for a udp ping, a host | |
223 | will be reported as unreachable if it is not running the | |
224 | appropriate echo service. For Unix-like systems see \fIinetd\fR\|(8) | |
225 | for more information. | |
226 | .PP | |
227 | If the \*(L"icmp\*(R" protocol is specified, the \fIping()\fR method sends an icmp | |
228 | echo message to the remote host, which is what the \s-1UNIX\s0 ping program | |
229 | does. If the echoed message is received from the remote host and | |
230 | the echoed information is correct, the remote host is considered | |
231 | reachable. Specifying the \*(L"icmp\*(R" protocol requires that the program | |
232 | be run as root or that the program be setuid to root. | |
233 | .PP | |
234 | If the \*(L"external\*(R" protocol is specified, the \fIping()\fR method attempts to | |
235 | use the \f(CW\*(C`Net::Ping::External\*(C'\fR module to ping the remote host. | |
236 | \&\f(CW\*(C`Net::Ping::External\*(C'\fR interfaces with your system's default \f(CW\*(C`ping\*(C'\fR | |
237 | utility to perform the ping, and generally produces relatively | |
238 | accurate results. If \f(CW\*(C`Net::Ping::External\*(C'\fR if not installed on your | |
239 | system, specifying the \*(L"external\*(R" protocol will result in an error. | |
240 | .PP | |
241 | If the \*(L"syn\*(R" protocol is specified, the \fIping()\fR method will only | |
242 | send a \s-1TCP\s0 \s-1SYN\s0 packet to the remote host then immediately return. | |
243 | If the syn packet was sent successfully, it will return a true value, | |
244 | otherwise it will return false. \s-1NOTE:\s0 Unlike the other protocols, | |
245 | the return value does \s-1NOT\s0 determine if the remote host is alive or | |
246 | not since the full \s-1TCP\s0 three-way handshake may not have completed | |
247 | yet. The remote host is only considered reachable if it receives | |
248 | a \s-1TCP\s0 \s-1ACK\s0 within the timeout specifed. To begin waiting for the | |
249 | \&\s-1ACK\s0 packets, use the \fIack()\fR method as explained below. Use the | |
250 | \&\*(L"syn\*(R" protocol instead the \*(L"tcp\*(R" protocol to determine reachability | |
251 | of multiple destinations simultaneously by sending parallel \s-1TCP\s0 | |
252 | \&\s-1SYN\s0 packets. It will not block while testing each remote host. | |
253 | demo/fping is provided in this distribution to demonstrate the | |
254 | \&\*(L"syn\*(R" protocol as an example. | |
255 | This protocol does not require any special privileges. | |
256 | .Sh "Functions" | |
257 | .IX Subsection "Functions" | |
258 | .ie n .IP "Net::Ping\->new([$proto [, $def_timeout\fR [, \f(CW$bytes\fR [, \f(CW$device\fR [, \f(CW$tos ]]]]]);" 4 | |
259 | .el .IP "Net::Ping\->new([$proto [, \f(CW$def_timeout\fR [, \f(CW$bytes\fR [, \f(CW$device\fR [, \f(CW$tos\fR ]]]]]);" 4 | |
260 | .IX Item "Net::Ping->new([$proto [, $def_timeout [, $bytes [, $device [, $tos ]]]]]);" | |
261 | Create a new ping object. All of the parameters are optional. \f(CW$proto\fR | |
262 | specifies the protocol to use when doing a ping. The current choices | |
263 | are \*(L"tcp\*(R", \*(L"udp\*(R", \*(L"icmp\*(R", \*(L"stream\*(R", \*(L"syn\*(R", or \*(L"external\*(R". | |
264 | The default is \*(L"tcp\*(R". | |
265 | .Sp | |
266 | If a default timeout ($def_timeout) in seconds is provided, it is used | |
267 | when a timeout is not given to the \fIping()\fR method (below). The timeout | |
268 | must be greater than 0 and the default, if not specified, is 5 seconds. | |
269 | .Sp | |
270 | If the number of data bytes ($bytes) is given, that many data bytes | |
271 | are included in the ping packet sent to the remote host. The number of | |
272 | data bytes is ignored if the protocol is \*(L"tcp\*(R". The minimum (and | |
273 | default) number of data bytes is 1 if the protocol is \*(L"udp\*(R" and 0 | |
274 | otherwise. The maximum number of data bytes that can be specified is | |
275 | 1024. | |
276 | .Sp | |
277 | If \f(CW$device\fR is given, this device is used to bind the source endpoint | |
278 | before sending the ping packet. I beleive this only works with | |
279 | superuser privileges and with udp and icmp protocols at this time. | |
280 | .Sp | |
281 | If \f(CW$tos\fR is given, this ToS is configured into the soscket. | |
282 | .ie n .IP "$p\->ping($host [, $timeout]);" 4 | |
283 | .el .IP "$p\->ping($host [, \f(CW$timeout\fR]);" 4 | |
284 | .IX Item "$p->ping($host [, $timeout]);" | |
285 | Ping the remote host and wait for a response. \f(CW$host\fR can be either the | |
286 | hostname or the \s-1IP\s0 number of the remote host. The optional timeout | |
287 | must be greater than 0 seconds and defaults to whatever was specified | |
288 | when the ping object was created. Returns a success flag. If the | |
289 | hostname cannot be found or there is a problem with the \s-1IP\s0 number, the | |
290 | success flag returned will be undef. Otherwise, the success flag will | |
291 | be 1 if the host is reachable and 0 if it is not. For most practical | |
292 | purposes, undef and 0 and can be treated as the same case. In array | |
293 | context, the elapsed time as well as the string form of the ip the | |
294 | host resolved to are also returned. The elapsed time value will | |
295 | be a float, as retuned by the \fITime::HiRes::time()\fR function, if \fIhires()\fR | |
296 | has been previously called, otherwise it is returned as an integer. | |
297 | .IP "$p\->source_verify( { 0 | 1 } );" 4 | |
298 | .IX Item "$p->source_verify( { 0 | 1 } );" | |
299 | Allows source endpoint verification to be enabled or disabled. | |
300 | This is useful for those remote destinations with multiples | |
301 | interfaces where the response may not originate from the same | |
302 | endpoint that the original destination endpoint was sent to. | |
303 | This only affects udp and icmp protocol pings. | |
304 | .Sp | |
305 | This is enabled by default. | |
306 | .IP "$p\->service_check( { 0 | 1 } );" 4 | |
307 | .IX Item "$p->service_check( { 0 | 1 } );" | |
308 | Set whether or not the connect behavior should enforce | |
309 | remote service availability as well as reachability. Normally, | |
310 | if the remote server reported \s-1ECONNREFUSED\s0, it must have been | |
311 | reachable because of the status packet that it reported. | |
312 | With this option enabled, the full three-way tcp handshake | |
313 | must have been established successfully before it will | |
314 | claim it is reachable. \s-1NOTE:\s0 It still does nothing more | |
315 | than connect and disconnect. It does not speak any protocol | |
316 | (i.e., \s-1HTTP\s0 or \s-1FTP\s0) to ensure the remote server is sane in | |
317 | any way. The remote server \s-1CPU\s0 could be grinding to a halt | |
318 | and unresponsive to any clients connecting, but if the kernel | |
319 | throws the \s-1ACK\s0 packet, it is considered alive anyway. To | |
320 | really determine if the server is responding well would be | |
321 | application specific and is beyond the scope of Net::Ping. | |
322 | For udp protocol, enabling this option demands that the | |
323 | remote server replies with the same udp data that it was sent | |
324 | as defined by the udp echo service. | |
325 | .Sp | |
326 | This affects the \*(L"udp\*(R", \*(L"tcp\*(R", and \*(L"syn\*(R" protocols. | |
327 | .Sp | |
328 | This is disabled by default. | |
329 | .IP "$p\->tcp_service_check( { 0 | 1 } );" 4 | |
330 | .IX Item "$p->tcp_service_check( { 0 | 1 } );" | |
331 | Depricated method, but does the same as \fIservice_check()\fR method. | |
332 | .IP "$p\->hires( { 0 | 1 } );" 4 | |
333 | .IX Item "$p->hires( { 0 | 1 } );" | |
334 | Causes this module to use Time::HiRes module, allowing milliseconds | |
335 | to be returned by subsequent calls to \fIping()\fR. | |
336 | .Sp | |
337 | This is disabled by default. | |
338 | .IP "$p\->bind($local_addr);" 4 | |
339 | .IX Item "$p->bind($local_addr);" | |
340 | Sets the source address from which pings will be sent. This must be | |
341 | the address of one of the interfaces on the local host. \f(CW$local_addr\fR | |
342 | may be specified as a hostname or as a text \s-1IP\s0 address such as | |
343 | \&\*(L"192.168.1.1\*(R". | |
344 | .Sp | |
345 | If the protocol is set to \*(L"tcp\*(R", this method may be called any | |
346 | number of times, and each call to the \fIping()\fR method (below) will use | |
347 | the most recent \f(CW$local_addr\fR. If the protocol is \*(L"icmp\*(R" or \*(L"udp\*(R", | |
348 | then \fIbind()\fR must be called at most once per object, and (if it is | |
349 | called at all) must be called before the first call to \fIping()\fR for that | |
350 | object. | |
351 | .IP "$p\->open($host);" 4 | |
352 | .IX Item "$p->open($host);" | |
353 | When you are using the \*(L"stream\*(R" protocol, this call pre-opens the | |
354 | tcp socket. It's only necessary to do this if you want to | |
355 | provide a different timeout when creating the connection, or | |
356 | remove the overhead of establishing the connection from the | |
357 | first ping. If you don't call \f(CW\*(C`open()\*(C'\fR, the connection is | |
358 | automatically opened the first time \f(CW\*(C`ping()\*(C'\fR is called. | |
359 | This call simply does nothing if you are using any protocol other | |
360 | than stream. | |
361 | .ie n .IP "$p\->ack( [ $host ] );" 4 | |
362 | .el .IP "$p\->ack( [ \f(CW$host\fR ] );" 4 | |
363 | .IX Item "$p->ack( [ $host ] );" | |
364 | When using the \*(L"syn\*(R" protocol, use this method to determine | |
365 | the reachability of the remote host. This method is meant | |
366 | to be called up to as many times as \fIping()\fR was called. Each | |
367 | call returns the host (as passed to \fIping()\fR) that came back | |
368 | with the \s-1TCP\s0 \s-1ACK\s0. The order in which the hosts are returned | |
369 | may not necessarily be the same order in which they were | |
370 | \&\s-1SYN\s0 queued using the \fIping()\fR method. If the timeout is | |
371 | reached before the \s-1TCP\s0 \s-1ACK\s0 is received, or if the remote | |
372 | host is not listening on the port attempted, then the \s-1TCP\s0 | |
373 | connection will not be established and \fIack()\fR will return | |
374 | undef. In list context, the host, the ack time, and the | |
375 | dotted ip string will be returned instead of just the host. | |
376 | If the optional \f(CW$host\fR argument is specified, the return | |
377 | value will be partaining to that host only. | |
378 | This call simply does nothing if you are using any protocol | |
379 | other than syn. | |
380 | .ie n .IP "$p\->nack( $failed_ack_host );" 4 | |
381 | .el .IP "$p\->nack( \f(CW$failed_ack_host\fR );" 4 | |
382 | .IX Item "$p->nack( $failed_ack_host );" | |
383 | The reason that host \f(CW$failed_ack_host\fR did not receive a | |
384 | valid \s-1ACK\s0. Useful to find out why when ack( \f(CW$fail_ack_host\fR ) | |
385 | returns a false value. | |
386 | .IP "$p\->\fIclose()\fR;" 4 | |
387 | .IX Item "$p->close();" | |
388 | Close the network connection for this ping object. The network | |
389 | connection is also closed by \*(L"undef \f(CW$p\fR\*(R". The network connection is | |
390 | automatically closed if the ping object goes out of scope (e.g. \f(CW$p\fR is | |
391 | local to a subroutine and you leave the subroutine). | |
392 | .ie n .IP "pingecho($host [, $timeout]);" 4 | |
393 | .el .IP "pingecho($host [, \f(CW$timeout\fR]);" 4 | |
394 | .IX Item "pingecho($host [, $timeout]);" | |
395 | To provide backward compatibility with the previous version of | |
396 | Net::Ping, a \fIpingecho()\fR subroutine is available with the same | |
397 | functionality as before. \fIpingecho()\fR uses the tcp protocol. The | |
398 | return values and parameters are the same as described for the \fIping()\fR | |
399 | method. This subroutine is obsolete and may be removed in a future | |
400 | version of Net::Ping. | |
401 | .SH "NOTES" | |
402 | .IX Header "NOTES" | |
403 | There will be less network overhead (and some efficiency in your | |
404 | program) if you specify either the udp or the icmp protocol. The tcp | |
405 | protocol will generate 2.5 times or more traffic for each ping than | |
406 | either udp or icmp. If many hosts are pinged frequently, you may wish | |
407 | to implement a small wait (e.g. 25ms or more) between each ping to | |
408 | avoid flooding your network with packets. | |
409 | .PP | |
410 | The icmp protocol requires that the program be run as root or that it | |
411 | be setuid to root. The other protocols do not require special | |
412 | privileges, but not all network devices implement tcp or udp echo. | |
413 | .PP | |
414 | Local hosts should normally respond to pings within milliseconds. | |
415 | However, on a very congested network it may take up to 3 seconds or | |
416 | longer to receive an echo packet from the remote host. If the timeout | |
417 | is set too low under these conditions, it will appear that the remote | |
418 | host is not reachable (which is almost the truth). | |
419 | .PP | |
420 | Reachability doesn't necessarily mean that the remote host is actually | |
421 | functioning beyond its ability to echo packets. tcp is slightly better | |
422 | at indicating the health of a system than icmp because it uses more | |
423 | of the networking stack to respond. | |
424 | .PP | |
425 | Because of a lack of anything better, this module uses its own | |
426 | routines to pack and unpack \s-1ICMP\s0 packets. It would be better for a | |
427 | separate module to be written which understands all of the different | |
428 | kinds of \s-1ICMP\s0 packets. | |
429 | .SH "INSTALL" | |
430 | .IX Header "INSTALL" | |
431 | The latest source tree is available via cvs: | |
432 | .PP | |
433 | .Vb 2 | |
434 | \& cvs -z3 -q -d :pserver:anonymous@cvs.roobik.com.:/usr/local/cvsroot/freeware checkout Net-Ping | |
435 | \& cd Net-Ping | |
436 | .Ve | |
437 | .PP | |
438 | The tarball can be created as follows: | |
439 | .PP | |
440 | .Vb 1 | |
441 | \& perl Makefile.PL ; make ; make dist | |
442 | .Ve | |
443 | .PP | |
444 | The latest Net::Ping release can be found at \s-1CPAN:\s0 | |
445 | .PP | |
446 | .Vb 1 | |
447 | \& $CPAN/modules/by-module/Net/ | |
448 | .Ve | |
449 | .PP | |
450 | 1) Extract the tarball | |
451 | .PP | |
452 | .Vb 2 | |
453 | \& gtar -zxvf Net-Ping-xxxx.tar.gz | |
454 | \& cd Net-Ping-xxxx | |
455 | .Ve | |
456 | .PP | |
457 | 2) Build: | |
458 | .PP | |
459 | .Vb 4 | |
460 | \& make realclean | |
461 | \& perl Makefile.PL | |
462 | \& make | |
463 | \& make test | |
464 | .Ve | |
465 | .PP | |
466 | 3) Install | |
467 | .PP | |
468 | .Vb 1 | |
469 | \& make install | |
470 | .Ve | |
471 | .PP | |
472 | Or install it \s-1RPM\s0 Style: | |
473 | .PP | |
474 | .Vb 1 | |
475 | \& rpm -ta SOURCES/Net-Ping-xxxx.tar.gz | |
476 | .Ve | |
477 | .PP | |
478 | .Vb 1 | |
479 | \& rpm -ih RPMS/noarch/perl-Net-Ping-xxxx.rpm | |
480 | .Ve | |
481 | .SH "BUGS" | |
482 | .IX Header "BUGS" | |
483 | For a list of known issues, visit: | |
484 | .PP | |
485 | https://rt.cpan.org/NoAuth/Bugs.html?Dist=Net\-Ping | |
486 | .PP | |
487 | To report a new bug, visit: | |
488 | .PP | |
489 | https://rt.cpan.org/NoAuth/ReportBug.html?Queue=Net\-Ping | |
490 | .SH "AUTHORS" | |
491 | .IX Header "AUTHORS" | |
492 | .Vb 2 | |
493 | \& Current maintainer: | |
494 | \& bbb@cpan.org (Rob Brown) | |
495 | .Ve | |
496 | .PP | |
497 | .Vb 2 | |
498 | \& External protocol: | |
499 | \& colinm@cpan.org (Colin McMillen) | |
500 | .Ve | |
501 | .PP | |
502 | .Vb 2 | |
503 | \& Stream protocol: | |
504 | \& bronson@trestle.com (Scott Bronson) | |
505 | .Ve | |
506 | .PP | |
507 | .Vb 3 | |
508 | \& Original pingecho(): | |
509 | \& karrer@bernina.ethz.ch (Andreas Karrer) | |
510 | \& pmarquess@bfsec.bt.co.uk (Paul Marquess) | |
511 | .Ve | |
512 | .PP | |
513 | .Vb 2 | |
514 | \& Original Net::Ping author: | |
515 | \& mose@ns.ccsn.edu (Russell Mosemann) | |
516 | .Ve | |
517 | .SH "COPYRIGHT" | |
518 | .IX Header "COPYRIGHT" | |
519 | Copyright (c) 2002\-2003, Rob Brown. All rights reserved. | |
520 | .PP | |
521 | Copyright (c) 2001, Colin McMillen. All rights reserved. | |
522 | .PP | |
523 | This program is free software; you may redistribute it and/or | |
524 | modify it under the same terms as Perl itself. | |
525 | .PP | |
526 | $Id: Ping.pm,v 1.86 2003/06/27 21:31:07 rob Exp $ |