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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. The default value is 1.
164 Source multicast packets with the given interface address.
165 This flag only applies if the ping destination is a multicast address.
170 .Em between sending each packet .
171 The default is to wait for one second between each packet.
172 The wait time may be fractional, but only the super-user may specify
173 values less than 1 second.
174 This option is incompatible with the
178 Suppress loopback of multicast packets.
179 This flag only applies if the ping destination is a multicast address.
185 sends that many packets as fast as possible before falling into its normal
187 Only the super-user may use this option.
188 .It Fl M Cm mask | time
197 print the netmask of the remote machine.
199 .Va net.inet.icmp.maskrepl
200 MIB variable to enable
204 print the origination, reception and transmission timestamps.
206 Set the IP Time To Live for outgoing packets.
207 If not specified, the kernel uses the value of the
212 No attempt will be made to lookup symbolic names for host addresses.
214 Exit successfully after receiving one reply packet.
217 specifies IPsec policy for the ping session.
218 For details please refer to
221 .Xr ipsec_set_policy 3 .
223 You may specify up to 16
225 bytes to fill out the packet you send.
226 This is useful for diagnosing data-dependent problems in a network.
229 will cause the sent packet to be filled with all
232 Somewhat quiet output.
234 display ICMP error messages that are in response to our query messages.
237 flag was required to display such errors, but
239 displays all ICMP error messages.
240 On a busy machine, this output can be overbearing.
245 prints out any ICMP error messages caused by its own ECHO_REQUEST
249 Nothing is displayed except the summary lines at startup time and
258 the route buffer on returned packets.
259 Note that the IP header is only large enough for nine such routes;
262 command is usually better at determining the route packets take to a
263 particular destination.
264 If more routes come back than should, such as due to an illegal spoofed
265 packet, ping will print the route list and then truncate it at the correct
267 Many hosts ignore or discard the
271 Bypass the normal routing tables and send directly to a host on an attached
273 If the host is not on a directly-attached network, an error is returned.
274 This option can be used to ping a local host through an interface
275 that has no route through it
276 (e.g., after the interface was dropped by
279 Use the following IP address as the source address in outgoing packets.
280 On hosts with more than one IP address, this option can be used to
281 force the source address to be something other than the IP address
282 of the interface the probe packet is sent on.
284 is not one of this machine's interface addresses, an error is
285 returned and nothing is sent.
286 .It Fl s Ar packetsize
287 Specify the number of data bytes to be sent.
288 The default is 56, which translates into 64
290 data bytes when combined
294 Only the super-user may specify values more than default.
295 This option cannot be used with ping sweeps.
297 Set the IP Time To Live for multicasted packets.
298 This flag only applies if the ping destination is a multicast address.
300 Specify a timeout, in seconds, before ping exits regardless of how
301 many packets have been received.
307 that are received are listed.
309 Use the specified type of service.
314 for fault isolation, it should first be run on the local host, to verify
315 that the local network interface is up and running.
316 Then, hosts and gateways further and further away should be
318 Round-trip times and packet loss statistics are computed.
319 If duplicate packets are received, they are not included in the packet
320 loss calculation, although the round trip time of these packets is used
321 in calculating the round-trip time statistics.
322 When the specified number of packets have been sent
324 or if the program is terminated with a
326 a brief summary is displayed, showing the number of packets sent and
327 received, and the minimum, mean, maximum, and standard deviation of
328 the round-trip times.
338 signal, the current number of packets sent and received, and the
339 minimum, mean, and maximum of the round-trip times will be written to
340 the standard error output.
342 This program is intended for use in network testing, measurement and
344 Because of the load it can impose on the network, it is unwise to use
346 during normal operations or from automated scripts.
347 .Sh ICMP PACKET DETAILS
348 An IP header without options is 20 bytes.
352 packet contains an additional 8 bytes worth of
354 header followed by an arbitrary amount of data.
357 is given, this indicated the size of this extra piece of data
359 Thus the amount of data received inside of an IP packet of type
362 will always be 8 bytes more than the requested data space
367 If the data space is at least eight bytes large,
369 uses the first eight bytes of this space to include a timestamp which
370 it uses in the computation of round trip times.
371 If less than eight bytes of pad are specified, no round trip times are
373 .Sh DUPLICATE AND DAMAGED PACKETS
376 utility will report duplicate and damaged packets.
377 Duplicate packets should never occur when pinging a unicast address,
378 and seem to be caused by
379 inappropriate link-level retransmissions.
380 Duplicates may occur in many situations and are rarely
382 a good sign, although the presence of low levels of duplicates may not
383 always be cause for alarm.
384 Duplicates are expected when pinging a broadcast or multicast address,
385 since they are not really duplicates but replies from different hosts
388 Damaged packets are obviously serious cause for alarm and often
389 indicate broken hardware somewhere in the
391 packet's path (in the network or in the hosts).
392 .Sh TRYING DIFFERENT DATA PATTERNS
395 layer should never treat packets differently depending on the data
396 contained in the data portion.
397 Unfortunately, data-dependent problems have been known to sneak into
398 networks and remain undetected for long periods of time.
399 In many cases the particular pattern that will have problems is something
400 that does not have sufficient
402 such as all ones or all zeros, or a pattern right at the edge, such as
405 necessarily enough to specify a data pattern of all zeros (for example)
406 on the command line because the pattern that is of interest is
407 at the data link level, and the relationship between what you type and
408 what the controllers transmit can be complicated.
410 This means that if you have a data-dependent problem you will probably
411 have to do a lot of testing to find it.
412 If you are lucky, you may manage to find a file that either
414 be sent across your network or that takes much longer to transfer than
415 other similar length files.
416 You can then examine this file for repeated patterns that you can test
424 value of an IP packet represents the maximum number of IP routers
425 that the packet can go through before being thrown away.
426 In current practice you can expect each router in the Internet to decrement
429 field by exactly one.
433 specification recommends setting the
437 packets to 64, but many systems use smaller values
443 The maximum possible value of this field is 255, and most
449 .Tn ICMP ECHO_REQUEST
451 This is why you will find you can
453 some hosts, but not reach them with
460 prints the ttl value from the packet it receives.
461 When a remote system receives a ping packet, it can do one of three things
464 field in its response:
467 Not change it; this is what
469 systems did before the
474 value in the received packet will be 255 minus the
475 number of routers in the round-trip path.
477 Set it to 255; this is what current
482 value in the received packet will be 255 minus the
483 number of routers in the path
491 Set it to some other value.
492 Some machines use the same value for
494 packets that they use for
496 packets, for example either 30 or 60.
497 Others may use completely wild values.
502 utility returns an exit status of zero if at least one response was
503 heard from the specified
505 a status of two if the transmission was successful but no responses
506 were received; or another value
509 if an error occurred.
523 utility was written by
525 while at the US Army Ballistics
528 Many Hosts and Gateways ignore the
532 The maximum IP header length is too small for options like
534 to be completely useful.
536 not much that can be done about this, however.
538 Flood pinging is not recommended in general, and flood pinging the
539 broadcast address should only be done under very controlled conditions.
543 option is not worth much on busy hosts.
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