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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
64 .Op Fl M Cm mask | time
69 .Op Fl s Ar packetsize
80 .No protocol Ap s mandatory
83 .Tn ICMP ECHO_RESPONSE
84 from a host or gateway.
92 and then an arbitrary number of
94 bytes used to fill out the packet.
95 The options are as follows:
96 .Bl -tag -width indent
102 character when no packet is received before the next packet
104 To cater for round-trip times that are longer than the interval
105 between transmissions, further missing packets cause a bell only
106 if the maximum number of unreceived packets has increased.
112 character in the output when any packet is received.
113 This option is ignored
114 if other format options are present.
121 If this option is not specified,
123 will operate until interrupted.
124 If this option is specified in conjunction with ping sweeps,
125 each sweep will consist of
129 Set the Don't Fragment bit.
133 option on the socket being used.
136 Outputs packets as fast as they come back or one hundred times per second,
142 is printed, while for every
144 received a backspace is printed.
145 This provides a rapid display of how many packets are being dropped.
146 Only the super-user may use this option.
148 This can be very hard on a network and should be used with caution.
150 .It Fl G Ar sweepmaxsize
151 Specify the maximum size of
153 payload when sending sweeping pings.
154 This option is required for ping sweeps.
155 .It Fl g Ar sweepminsize
158 payload to start with when sending sweeping pings.
159 The default value is 0.
160 .It Fl h Ar sweepincrsize
161 Specify the number of bytes to increment the size of
164 each sweep when sending sweeping pings.
165 The default value is 1.
167 Source multicast packets with the given interface address.
168 This flag only applies if the ping destination is a multicast address.
173 .Em between sending each packet .
174 The default is to wait for one second between each packet.
175 The wait time may be fractional, but only the super-user may specify
176 values less than 1 second.
177 This option is incompatible with the
181 Suppress loopback of multicast packets.
182 This flag only applies if the ping destination is a multicast address.
188 sends that many packets as fast as possible before falling into its normal
190 Only the super-user may use this option.
191 .It Fl M Cm mask | time
200 print the netmask of the remote machine.
202 .Va net.inet.icmp.maskrepl
203 MIB variable to enable
206 .Va net.inet.icmp.maskfake
207 if you want to override the netmask in the response.
210 print the origination, reception and transmission timestamps.
212 .Va net.inet.icmp.tstamprepl
213 MIB variable to enable or disable
214 .Dv ICMP_TSTAMPREPLY .
216 Set the IP Time To Live for outgoing packets.
217 If not specified, the kernel uses the value of the
222 No attempt will be made to lookup symbolic names for host addresses.
224 Exit successfully after receiving one reply packet.
227 specifies IPsec policy for the ping session.
228 For details please refer to
231 .Xr ipsec_set_policy 3 .
233 You may specify up to 16
235 bytes to fill out the packet you send.
236 This is useful for diagnosing data-dependent problems in a network.
239 will cause the sent packet to be filled with all
242 Somewhat quiet output.
244 display ICMP error messages that are in response to our query messages.
247 flag was required to display such errors, but
249 displays all ICMP error messages.
250 On a busy machine, this output can be overbearing.
255 prints out any ICMP error messages caused by its own ECHO_REQUEST
259 Nothing is displayed except the summary lines at startup time and
268 the route buffer on returned packets.
269 Note that the IP header is only large enough for nine such routes;
272 command is usually better at determining the route packets take to a
273 particular destination.
274 If more routes come back than should, such as due to an illegal spoofed
275 packet, ping will print the route list and then truncate it at the correct
277 Many hosts ignore or discard the
281 Bypass the normal routing tables and send directly to a host on an attached
283 If the host is not on a directly-attached network, an error is returned.
284 This option can be used to ping a local host through an interface
285 that has no route through it
286 (e.g., after the interface was dropped by
289 Use the following IP address as the source address in outgoing packets.
290 On hosts with more than one IP address, this option can be used to
291 force the source address to be something other than the IP address
292 of the interface the probe packet is sent on.
294 is not one of this machine's interface addresses, an error is
295 returned and nothing is sent.
296 .It Fl s Ar packetsize
297 Specify the number of data bytes to be sent.
298 The default is 56, which translates into 64
300 data bytes when combined
304 Only the super-user may specify values more than default.
305 This option cannot be used with ping sweeps.
307 Set the IP Time To Live for multicasted packets.
308 This flag only applies if the ping destination is a multicast address.
310 Specify a timeout, in seconds, before ping exits regardless of how
311 many packets have been received.
317 that are received are listed.
319 Time in milliseconds to wait for a reply for each packet sent.
320 If a reply arrives later, the packet is not printed as replied, but
321 considered as replied when calculating statistics.
323 Use the specified type of service.
328 for fault isolation, it should first be run on the local host, to verify
329 that the local network interface is up and running.
330 Then, hosts and gateways further and further away should be
332 Round-trip times and packet loss statistics are computed.
333 If duplicate packets are received, they are not included in the packet
334 loss calculation, although the round trip time of these packets is used
335 in calculating the round-trip time statistics.
336 When the specified number of packets have been sent
338 or if the program is terminated with a
340 a brief summary is displayed, showing the number of packets sent and
341 received, and the minimum, mean, maximum, and standard deviation of
342 the round-trip times.
352 signal, the current number of packets sent and received, and the
353 minimum, mean, and maximum of the round-trip times will be written to
354 the standard error output.
356 This program is intended for use in network testing, measurement and
358 Because of the load it can impose on the network, it is unwise to use
360 during normal operations or from automated scripts.
361 .Sh ICMP PACKET DETAILS
362 An IP header without options is 20 bytes.
366 packet contains an additional 8 bytes worth of
368 header followed by an arbitrary amount of data.
371 is given, this indicated the size of this extra piece of data
373 Thus the amount of data received inside of an IP packet of type
376 will always be 8 bytes more than the requested data space
381 If the data space is at least eight bytes large,
383 uses the first eight bytes of this space to include a timestamp which
384 it uses in the computation of round trip times.
385 If less than eight bytes of pad are specified, no round trip times are
387 .Sh DUPLICATE AND DAMAGED PACKETS
390 utility will report duplicate and damaged packets.
391 Duplicate packets should never occur when pinging a unicast address,
392 and seem to be caused by
393 inappropriate link-level retransmissions.
394 Duplicates may occur in many situations and are rarely
396 a good sign, although the presence of low levels of duplicates may not
397 always be cause for alarm.
398 Duplicates are expected when pinging a broadcast or multicast address,
399 since they are not really duplicates but replies from different hosts
402 Damaged packets are obviously serious cause for alarm and often
403 indicate broken hardware somewhere in the
405 packet's path (in the network or in the hosts).
406 .Sh TRYING DIFFERENT DATA PATTERNS
409 layer should never treat packets differently depending on the data
410 contained in the data portion.
411 Unfortunately, data-dependent problems have been known to sneak into
412 networks and remain undetected for long periods of time.
413 In many cases the particular pattern that will have problems is something
414 that does not have sufficient
416 such as all ones or all zeros, or a pattern right at the edge, such as
419 necessarily enough to specify a data pattern of all zeros (for example)
420 on the command line because the pattern that is of interest is
421 at the data link level, and the relationship between what you type and
422 what the controllers transmit can be complicated.
424 This means that if you have a data-dependent problem you will probably
425 have to do a lot of testing to find it.
426 If you are lucky, you may manage to find a file that either
428 be sent across your network or that takes much longer to transfer than
429 other similar length files.
430 You can then examine this file for repeated patterns that you can test
438 value of an IP packet represents the maximum number of IP routers
439 that the packet can go through before being thrown away.
440 In current practice you can expect each router in the Internet to decrement
443 field by exactly one.
447 specification recommends setting the
451 packets to 64, but many systems use smaller values
457 The maximum possible value of this field is 255, and most
463 .Tn ICMP ECHO_REQUEST
465 This is why you will find you can
467 some hosts, but not reach them with
474 prints the ttl value from the packet it receives.
475 When a remote system receives a ping packet, it can do one of three things
478 field in its response:
481 Not change it; this is what
483 systems did before the
488 value in the received packet will be 255 minus the
489 number of routers in the round-trip path.
491 Set it to 255; this is what current
496 value in the received packet will be 255 minus the
497 number of routers in the path
505 Set it to some other value.
506 Some machines use the same value for
508 packets that they use for
510 packets, for example either 30 or 60.
511 Others may use completely wild values.
516 utility exits with one of the following values:
517 .Bl -tag -width indent
519 At least one response was heard from the specified
522 The transmission was successful but no responses were received.
525 These values are defined in
542 utility was written by
544 while at the US Army Ballistics
547 Many Hosts and Gateways ignore the
551 The maximum IP header length is too small for options like
553 to be completely useful.
555 not much that can be done about this, however.
557 Flood pinging is not recommended in general, and flood pinging the
558 broadcast address should only be done under very controlled conditions.
562 option is not worth much on busy hosts.