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28 .\" @(#)ping.8 8.2 (Berkeley) 12/11/93
38 packets to network hosts
43 .Op Fl G Ar sweepmaxsize
44 .Op Fl g Ar sweepminsize
45 .Op Fl h Ar sweepincrsize
48 .Op Fl M Cm mask | time
53 .Op Fl s Ar packetsize
63 .Op Fl M Cm mask | time
68 .Op Fl s Ar packetsize
78 .No protocol Ap s mandatory
81 .Tn ICMP ECHO_RESPONSE
82 from a host or gateway.
90 and then an arbitrary number of
92 bytes used to fill out the packet.
93 The options are as follows:
94 .Bl -tag -width indent
100 character when no packet is received before the next packet
102 To cater for round-trip times that are longer than the interval
103 between transmissions, further missing packets cause a bell only
104 if the maximum number of unreceived packets has increased.
110 character in the output when any packet is received.
111 This option is ignored
112 if other format options are present.
119 If this option is not specified,
121 will operate until interrupted.
122 If this option is specified in conjunction with ping sweeps,
123 each sweep will consist of
127 Set the Don't Fragment bit.
131 option on the socket being used.
134 Outputs packets as fast as they come back or one hundred times per second,
140 is printed, while for every
142 received a backspace is printed.
143 This provides a rapid display of how many packets are being dropped.
144 Only the super-user may use this option.
146 This can be very hard on a network and should be used with caution.
148 .It Fl G Ar sweepmaxsize
149 Specify the maximum size of
151 payload when sending sweeping pings.
152 This option is required for ping sweeps.
153 .It Fl g Ar sweepminsize
156 payload to start with when sending sweeping pings.
157 The default value is 0.
158 .It Fl h Ar sweepincrsize
159 Specify the number of bytes to increment the size of
162 each sweep when sending sweeping pings.
163 The default value is 1.
165 Source multicast packets with the given interface address.
166 This flag only applies if the ping destination is a multicast address.
171 .Em between sending each packet .
172 The default is to wait for one second between each packet.
173 The wait time may be fractional, but only the super-user may specify
174 values less than 1 second.
175 This option is incompatible with the
179 Suppress loopback of multicast packets.
180 This flag only applies if the ping destination is a multicast address.
186 sends that many packets as fast as possible before falling into its normal
188 Only the super-user may use this option.
189 .It Fl M Cm mask | time
198 print the netmask of the remote machine.
200 .Va net.inet.icmp.maskrepl
201 MIB variable to enable
205 print the origination, reception and transmission timestamps.
207 Set the IP Time To Live for outgoing packets.
208 If not specified, the kernel uses the value of the
213 No attempt will be made to lookup symbolic names for host addresses.
215 Exit successfully after receiving one reply packet.
218 specifies IPsec policy for the ping session.
219 For details please refer to
222 .Xr ipsec_set_policy 3 .
224 You may specify up to 16
226 bytes to fill out the packet you send.
227 This is useful for diagnosing data-dependent problems in a network.
230 will cause the sent packet to be filled with all
233 Somewhat quiet output.
235 display ICMP error messages that are in response to our query messages.
238 flag was required to display such errors, but
240 displays all ICMP error messages.
241 On a busy machine, this output can be overbearing.
246 prints out any ICMP error messages caused by its own ECHO_REQUEST
250 Nothing is displayed except the summary lines at startup time and
259 the route buffer on returned packets.
260 Note that the IP header is only large enough for nine such routes;
263 command is usually better at determining the route packets take to a
264 particular destination.
265 If more routes come back than should, such as due to an illegal spoofed
266 packet, ping will print the route list and then truncate it at the correct
268 Many hosts ignore or discard the
272 Bypass the normal routing tables and send directly to a host on an attached
274 If the host is not on a directly-attached network, an error is returned.
275 This option can be used to ping a local host through an interface
276 that has no route through it
277 (e.g., after the interface was dropped by
280 Use the following IP address as the source address in outgoing packets.
281 On hosts with more than one IP address, this option can be used to
282 force the source address to be something other than the IP address
283 of the interface the probe packet is sent on.
285 is not one of this machine's interface addresses, an error is
286 returned and nothing is sent.
287 .It Fl s Ar packetsize
288 Specify the number of data bytes to be sent.
289 The default is 56, which translates into 64
291 data bytes when combined
295 Only the super-user may specify values more than default.
296 This option cannot be used with ping sweeps.
298 Set the IP Time To Live for multicasted packets.
299 This flag only applies if the ping destination is a multicast address.
301 Specify a timeout, in seconds, before ping exits regardless of how
302 many packets have been received.
308 that are received are listed.
310 Use the specified type of service.
315 for fault isolation, it should first be run on the local host, to verify
316 that the local network interface is up and running.
317 Then, hosts and gateways further and further away should be
319 Round-trip times and packet loss statistics are computed.
320 If duplicate packets are received, they are not included in the packet
321 loss calculation, although the round trip time of these packets is used
322 in calculating the round-trip time statistics.
323 When the specified number of packets have been sent
325 or if the program is terminated with a
327 a brief summary is displayed, showing the number of packets sent and
328 received, and the minimum, mean, maximum, and standard deviation of
329 the round-trip times.
339 signal, the current number of packets sent and received, and the
340 minimum, mean, and maximum of the round-trip times will be written to
341 the standard error output.
343 This program is intended for use in network testing, measurement and
345 Because of the load it can impose on the network, it is unwise to use
347 during normal operations or from automated scripts.
348 .Sh ICMP PACKET DETAILS
349 An IP header without options is 20 bytes.
353 packet contains an additional 8 bytes worth of
355 header followed by an arbitrary amount of data.
358 is given, this indicated the size of this extra piece of data
360 Thus the amount of data received inside of an IP packet of type
363 will always be 8 bytes more than the requested data space
368 If the data space is at least eight bytes large,
370 uses the first eight bytes of this space to include a timestamp which
371 it uses in the computation of round trip times.
372 If less than eight bytes of pad are specified, no round trip times are
374 .Sh DUPLICATE AND DAMAGED PACKETS
377 utility will report duplicate and damaged packets.
378 Duplicate packets should never occur when pinging a unicast address,
379 and seem to be caused by
380 inappropriate link-level retransmissions.
381 Duplicates may occur in many situations and are rarely
383 a good sign, although the presence of low levels of duplicates may not
384 always be cause for alarm.
385 Duplicates are expected when pinging a broadcast or multicast address,
386 since they are not really duplicates but replies from different hosts
389 Damaged packets are obviously serious cause for alarm and often
390 indicate broken hardware somewhere in the
392 packet's path (in the network or in the hosts).
393 .Sh TRYING DIFFERENT DATA PATTERNS
396 layer should never treat packets differently depending on the data
397 contained in the data portion.
398 Unfortunately, data-dependent problems have been known to sneak into
399 networks and remain undetected for long periods of time.
400 In many cases the particular pattern that will have problems is something
401 that does not have sufficient
403 such as all ones or all zeros, or a pattern right at the edge, such as
406 necessarily enough to specify a data pattern of all zeros (for example)
407 on the command line because the pattern that is of interest is
408 at the data link level, and the relationship between what you type and
409 what the controllers transmit can be complicated.
411 This means that if you have a data-dependent problem you will probably
412 have to do a lot of testing to find it.
413 If you are lucky, you may manage to find a file that either
415 be sent across your network or that takes much longer to transfer than
416 other similar length files.
417 You can then examine this file for repeated patterns that you can test
425 value of an IP packet represents the maximum number of IP routers
426 that the packet can go through before being thrown away.
427 In current practice you can expect each router in the Internet to decrement
430 field by exactly one.
434 specification recommends setting the
438 packets to 64, but many systems use smaller values
444 The maximum possible value of this field is 255, and most
450 .Tn ICMP ECHO_REQUEST
452 This is why you will find you can
454 some hosts, but not reach them with
461 prints the ttl value from the packet it receives.
462 When a remote system receives a ping packet, it can do one of three things
465 field in its response:
468 Not change it; this is what
470 systems did before the
475 value in the received packet will be 255 minus the
476 number of routers in the round-trip path.
478 Set it to 255; this is what current
483 value in the received packet will be 255 minus the
484 number of routers in the path
492 Set it to some other value.
493 Some machines use the same value for
495 packets that they use for
497 packets, for example either 30 or 60.
498 Others may use completely wild values.
503 utility returns an exit status of zero if at least one response was
504 heard from the specified
506 a status of two if the transmission was successful but no responses
507 were received; or another value
510 if an error occurred.
524 utility was written by
526 while at the US Army Ballistics
529 Many Hosts and Gateways ignore the
533 The maximum IP header length is too small for options like
535 to be completely useful.
537 not much that can be done about this, however.
539 Flood pinging is not recommended in general, and flood pinging the
540 broadcast address should only be done under very controlled conditions.
544 option is not worth much on busy hosts.
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