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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.
162 Try to do a reverse DNS lookup when displaying addresses.
163 This is the opposite of the
166 .It Fl h Ar sweepincrsize
167 Specify the number of bytes to increment the size of
170 each sweep when sending sweeping pings.
171 The default value is 1.
173 Source multicast packets with the given interface address.
174 This flag only applies if the ping destination is a multicast address.
179 .Em between sending each packet .
180 The default is to wait for one second between each packet.
181 The wait time may be fractional, but only the super-user may specify
182 values less than 1 second.
183 This option is incompatible with the
187 Suppress loopback of multicast packets.
188 This flag only applies if the ping destination is a multicast address.
194 sends that many packets as fast as possible before falling into its normal
196 Only the super-user may use this option.
197 .It Fl M Cm mask | time
206 print the netmask of the remote machine.
208 .Va net.inet.icmp.maskrepl
209 MIB variable to enable
212 .Va net.inet.icmp.maskfake
213 if you want to override the netmask in the response.
216 print the origination, reception and transmission timestamps.
218 .Va net.inet.icmp.tstamprepl
219 MIB variable to enable or disable
220 .Dv ICMP_TSTAMPREPLY .
222 Set the IP Time To Live for outgoing packets.
223 If not specified, the kernel uses the value of the
228 No attempt will be made to lookup symbolic names for host addresses.
229 This is the opposite of
231 and it is the default behavior.
233 Exit successfully after receiving one reply packet.
236 specifies IPsec policy for the ping session.
237 For details please refer to
240 .Xr ipsec_set_policy 3 .
242 You may specify up to 16
244 bytes to fill out the packet you send.
245 This is useful for diagnosing data-dependent problems in a network.
248 will cause the sent packet to be filled with all
251 Somewhat quiet output.
253 display ICMP error messages that are in response to our query messages.
256 flag was required to display such errors, but
258 displays all ICMP error messages.
259 On a busy machine, this output can be overbearing.
264 prints out any ICMP error messages caused by its own ECHO_REQUEST
268 Nothing is displayed except the summary lines at startup time and
277 the route buffer on returned packets.
278 Note that the IP header is only large enough for nine such routes;
281 command is usually better at determining the route packets take to a
282 particular destination.
283 If more routes come back than should, such as due to an illegal spoofed
284 packet, ping will print the route list and then truncate it at the correct
286 Many hosts ignore or discard the
290 Bypass the normal routing tables and send directly to a host on an attached
292 If the host is not on a directly-attached network, an error is returned.
293 This option can be used to ping a local host through an interface
294 that has no route through it
295 (e.g., after the interface was dropped by
298 Use the following IP address as the source address in outgoing packets.
299 On hosts with more than one IP address, this option can be used to
300 force the source address to be something other than the IP address
301 of the interface the probe packet is sent on.
303 is not one of this machine's interface addresses, an error is
304 returned and nothing is sent.
305 .It Fl s Ar packetsize
306 Specify the number of data bytes to be sent.
307 The default is 56, which translates into 64
309 data bytes when combined
313 Only the super-user may specify values more than default.
314 This option cannot be used with ping sweeps.
316 Set the IP Time To Live for multicasted packets.
317 This flag only applies if the ping destination is a multicast address.
319 Specify a timeout, in seconds, before ping exits regardless of how
320 many packets have been received.
326 that are received are listed.
328 Time in milliseconds to wait for a reply for each packet sent.
329 If a reply arrives later, the packet is not printed as replied, but
330 considered as replied when calculating statistics.
332 Use the specified type of service.
337 for fault isolation, it should first be run on the local host, to verify
338 that the local network interface is up and running.
339 Then, hosts and gateways further and further away should be
341 Round-trip times and packet loss statistics are computed.
342 If duplicate packets are received, they are not included in the packet
343 loss calculation, although the round trip time of these packets is used
344 in calculating the round-trip time statistics.
345 When the specified number of packets have been sent
347 or if the program is terminated with a
349 a brief summary is displayed, showing the number of packets sent and
350 received, and the minimum, mean, maximum, and standard deviation of
351 the round-trip times.
361 signal, the current number of packets sent and received, and the
362 minimum, mean, and maximum of the round-trip times will be written to
363 the standard error output.
365 This program is intended for use in network testing, measurement and
367 Because of the load it can impose on the network, it is unwise to use
369 during normal operations or from automated scripts.
370 .Sh ICMP PACKET DETAILS
371 An IP header without options is 20 bytes.
375 packet contains an additional 8 bytes worth of
377 header followed by an arbitrary amount of data.
380 is given, this indicated the size of this extra piece of data
382 Thus the amount of data received inside of an IP packet of type
385 will always be 8 bytes more than the requested data space
390 If the data space is at least eight bytes large,
392 uses the first eight bytes of this space to include a timestamp which
393 it uses in the computation of round trip times.
394 If less than eight bytes of pad are specified, no round trip times are
396 .Sh DUPLICATE AND DAMAGED PACKETS
399 utility will report duplicate and damaged packets.
400 Duplicate packets should never occur when pinging a unicast address,
401 and seem to be caused by
402 inappropriate link-level retransmissions.
403 Duplicates may occur in many situations and are rarely
405 a good sign, although the presence of low levels of duplicates may not
406 always be cause for alarm.
407 Duplicates are expected when pinging a broadcast or multicast address,
408 since they are not really duplicates but replies from different hosts
411 Damaged packets are obviously serious cause for alarm and often
412 indicate broken hardware somewhere in the
414 packet's path (in the network or in the hosts).
415 .Sh TRYING DIFFERENT DATA PATTERNS
418 layer should never treat packets differently depending on the data
419 contained in the data portion.
420 Unfortunately, data-dependent problems have been known to sneak into
421 networks and remain undetected for long periods of time.
422 In many cases the particular pattern that will have problems is something
423 that does not have sufficient
425 such as all ones or all zeros, or a pattern right at the edge, such as
428 necessarily enough to specify a data pattern of all zeros (for example)
429 on the command line because the pattern that is of interest is
430 at the data link level, and the relationship between what you type and
431 what the controllers transmit can be complicated.
433 This means that if you have a data-dependent problem you will probably
434 have to do a lot of testing to find it.
435 If you are lucky, you may manage to find a file that either
437 be sent across your network or that takes much longer to transfer than
438 other similar length files.
439 You can then examine this file for repeated patterns that you can test
447 value of an IP packet represents the maximum number of IP routers
448 that the packet can go through before being thrown away.
449 In current practice you can expect each router in the Internet to decrement
452 field by exactly one.
456 specification recommends setting the
460 packets to 64, but many systems use smaller values
466 The maximum possible value of this field is 255, and most
472 .Tn ICMP ECHO_REQUEST
474 This is why you will find you can
476 some hosts, but not reach them with
483 prints the ttl value from the packet it receives.
484 When a remote system receives a ping packet, it can do one of three things
487 field in its response:
490 Not change it; this is what
492 systems did before the
497 value in the received packet will be 255 minus the
498 number of routers in the round-trip path.
500 Set it to 255; this is what current
505 value in the received packet will be 255 minus the
506 number of routers in the path
514 Set it to some other value.
515 Some machines use the same value for
517 packets that they use for
519 packets, for example either 30 or 60.
520 Others may use completely wild values.
525 utility exits with one of the following values:
526 .Bl -tag -width indent
528 At least one response was heard from the specified
531 The transmission was successful but no responses were received.
534 These values are defined in
551 utility was written by
553 while at the US Army Ballistics
556 Many Hosts and Gateways ignore the
560 The maximum IP header length is too small for options like
562 to be completely useful.
564 not much that can be done about this, however.
566 Flood pinging is not recommended in general, and flood pinging the
567 broadcast address should only be done under very controlled conditions.
571 option is not worth much on busy hosts.
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