1 .\" Copyright (c) 1985, 1991, 1993
2 .\" The Regents of the University of California. All rights reserved.
4 .\" Redistribution and use in source and binary forms, with or without
5 .\" modification, are permitted provided that the following conditions
7 .\" 1. Redistributions of source code must retain the above copyright
8 .\" notice, this list of conditions and the following disclaimer.
9 .\" 2. Redistributions in binary form must reproduce the above copyright
10 .\" notice, this list of conditions and the following disclaimer in the
11 .\" documentation and/or other materials provided with the distribution.
12 .\" 3. All advertising materials mentioning features or use of this software
13 .\" must display the following acknowledgement:
14 .\" This product includes software developed by the University of
15 .\" California, Berkeley and its contributors.
16 .\" 4. Neither the name of the University nor the names of its contributors
17 .\" may be used to endorse or promote products derived from this software
18 .\" without specific prior written permission.
20 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 .\" @(#)ping.8 8.2 (Berkeley) 12/11/93
42 packets to network hosts
49 .Op Fl M Cm mask | time
54 .Op Fl s Ar packetsize
64 .Op Fl M Cm mask | time
69 .Op Fl s Ar packetsize
79 .No protocol Ap s mandatory
82 .Tn ICMP ECHO_RESPONSE
83 from a host or gateway.
91 and then an arbitrary number of
93 bytes used to fill out the packet.
94 The options are as follows:
95 .Bl -tag -width indent
101 character when no packet is received before the next packet
103 To cater for round-trip times that are longer than the interval
104 between transmissions, further missing packets cause a bell only
105 if the maximum number of unreceived packets has increased.
111 character in the output when any packet is received.
112 This option is ignored
113 if other format options are present.
120 If this option is not specified,
122 will operate until interrupted.
124 Set the Don't Fragment bit.
128 option on the socket being used.
131 Outputs packets as fast as they come back or one hundred times per second,
137 is printed, while for every
139 received a backspace is printed.
140 This provides a rapid display of how many packets are being dropped.
141 Only the super-user may use this option.
143 This can be very hard on a network and should be used with caution.
146 Source multicast packets with the given interface address.
147 This flag only applies if the ping destination is a multicast address.
152 .Em between sending each packet .
153 The default is to wait for one second between each packet.
154 The wait time may be fractional, but only the super-user may specify
155 values less than 1 second.
156 This option is incompatible with the
160 Suppress loopback of multicast packets.
161 This flag only applies if the ping destination is a multicast address.
167 sends that many packets as fast as possible before falling into its normal
169 Only the super-user may use this option.
170 .It Fl M Cm mask | time
179 print the netmask of the remote machine.
181 .Va net.inet.icmp.maskrepl
182 MIB variable to enable
186 print the origination, reception and transmission timestamps.
188 Set the IP Time To Live for outgoing packets.
189 If not specified, the kernel uses the value of the
194 No attempt will be made to lookup symbolic names for host addresses.
196 Exit successfully after receiving one reply packet.
199 specifies IPsec policy for the ping session.
200 For details please refer to
203 .Xr ipsec_set_policy 3 .
205 You may specify up to 16
207 bytes to fill out the packet you send.
208 This is useful for diagnosing data-dependent problems in a network.
211 will cause the sent packet to be filled with all
214 Somewhat quiet output.
216 display ICMP error messages that are in response to our query messages.
219 flag was required to display such errors, but
221 displays all ICMP error messages.
222 On a busy machine, this output can be overbearing.
227 prints out any ICMP error messages caused by its own ECHO_REQUEST
231 Nothing is displayed except the summary lines at startup time and
240 the route buffer on returned packets.
241 Note that the IP header is only large enough for nine such routes;
244 command is usually better at determining the route packets take to a
245 particular destination.
246 If more routes come back than should, such as due to an illegal spoofed
247 packet, ping will print the route list and then truncate it at the correct
249 Many hosts ignore or discard the
253 Bypass the normal routing tables and send directly to a host on an attached
255 If the host is not on a directly-attached network, an error is returned.
256 This option can be used to ping a local host through an interface
257 that has no route through it
258 (e.g., after the interface was dropped by
261 Use the following IP address as the source address in outgoing packets.
262 On hosts with more than one IP address, this option can be used to
263 force the source address to be something other than the IP address
264 of the interface the probe packet is sent on.
266 is not one of this machine's interface addresses, an error is
267 returned and nothing is sent.
268 .It Fl s Ar packetsize
269 Specify the number of data bytes to be sent.
270 The default is 56, which translates into 64
272 data bytes when combined
276 Only the super-user may specify values more than default.
278 Set the IP Time To Live for multicasted packets.
279 This flag only applies if the ping destination is a multicast address.
281 Specify a timeout, in seconds, before ping exits regardless of how
282 many packets have been received.
288 that are received are listed.
290 Use the specified type of service.
295 for fault isolation, it should first be run on the local host, to verify
296 that the local network interface is up and running.
297 Then, hosts and gateways further and further away should be
299 Round-trip times and packet loss statistics are computed.
300 If duplicate packets are received, they are not included in the packet
301 loss calculation, although the round trip time of these packets is used
302 in calculating the round-trip time statistics.
303 When the specified number of packets have been sent
305 or if the program is terminated with a
307 a brief summary is displayed, showing the number of packets sent and
308 received, and the minimum, mean, maximum, and standard deviation of
309 the round-trip times.
319 signal, the current number of packets sent and received, and the
320 minimum, mean, and maximum of the round-trip times will be written to
321 the standard error output.
323 This program is intended for use in network testing, measurement and
325 Because of the load it can impose on the network, it is unwise to use
327 during normal operations or from automated scripts.
328 .Sh ICMP PACKET DETAILS
329 An IP header without options is 20 bytes.
333 packet contains an additional 8 bytes worth of
335 header followed by an arbitrary amount of data.
338 is given, this indicated the size of this extra piece of data
340 Thus the amount of data received inside of an IP packet of type
343 will always be 8 bytes more than the requested data space
348 If the data space is at least eight bytes large,
350 uses the first eight bytes of this space to include a timestamp which
351 it uses in the computation of round trip times.
352 If less than eight bytes of pad are specified, no round trip times are
354 .Sh DUPLICATE AND DAMAGED PACKETS
357 utility will report duplicate and damaged packets.
358 Duplicate packets should never occur when pinging a unicast address,
359 and seem to be caused by
360 inappropriate link-level retransmissions.
361 Duplicates may occur in many situations and are rarely
363 a good sign, although the presence of low levels of duplicates may not
364 always be cause for alarm.
365 Duplicates are expected when pinging a broadcast or multicast address,
366 since they are not really duplicates but replies from different hosts
369 Damaged packets are obviously serious cause for alarm and often
370 indicate broken hardware somewhere in the
372 packet's path (in the network or in the hosts).
373 .Sh TRYING DIFFERENT DATA PATTERNS
376 layer should never treat packets differently depending on the data
377 contained in the data portion.
378 Unfortunately, data-dependent problems have been known to sneak into
379 networks and remain undetected for long periods of time.
380 In many cases the particular pattern that will have problems is something
381 that does not have sufficient
383 such as all ones or all zeros, or a pattern right at the edge, such as
386 necessarily enough to specify a data pattern of all zeros (for example)
387 on the command line because the pattern that is of interest is
388 at the data link level, and the relationship between what you type and
389 what the controllers transmit can be complicated.
391 This means that if you have a data-dependent problem you will probably
392 have to do a lot of testing to find it.
393 If you are lucky, you may manage to find a file that either
395 be sent across your network or that takes much longer to transfer than
396 other similar length files.
397 You can then examine this file for repeated patterns that you can test
405 value of an IP packet represents the maximum number of IP routers
406 that the packet can go through before being thrown away.
407 In current practice you can expect each router in the Internet to decrement
410 field by exactly one.
414 specification recommends setting the
418 packets to 64, but many systems use smaller values
424 The maximum possible value of this field is 255, and most
430 .Tn ICMP ECHO_REQUEST
432 This is why you will find you can
434 some hosts, but not reach them with
441 prints the ttl value from the packet it receives.
442 When a remote system receives a ping packet, it can do one of three things
445 field in its response:
448 Not change it; this is what
450 systems did before the
455 value in the received packet will be 255 minus the
456 number of routers in the round-trip path.
458 Set it to 255; this is what current
463 value in the received packet will be 255 minus the
464 number of routers in the path
472 Set it to some other value.
473 Some machines use the same value for
475 packets that they use for
477 packets, for example either 30 or 60.
478 Others may use completely wild values.
483 utility returns an exit status of zero if at least one response was
484 heard from the specified
486 a status of two if the transmission was successful but no responses
487 were received; or another value
490 if an error occurred.
504 utility was written by
506 while at the US Army Ballistics
509 Many Hosts and Gateways ignore the
513 The maximum IP header length is too small for options like
515 to be completely useful.
517 not much that can be done about this, however.
519 Flood pinging is not recommended in general, and flood pinging the
520 broadcast address should only be done under very controlled conditions.
524 option is not worth much on busy hosts.
projects / FreeBSD / FreeBSD.git / blob