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28 .\" @(#)ping.8 8.2 (Berkeley) 12/11/93
38 packets to network hosts
44 .Op Fl G Ar sweepmaxsize
45 .Op Fl g Ar sweepminsize
46 .Op Fl h Ar sweepincrsize
49 .Op Fl M Cm mask | time
54 .Op Fl s Ar packetsize
66 .Op Fl M Cm mask | time
71 .Op Fl s Ar packetsize
82 .No protocol Ap s mandatory
85 .Tn ICMP ECHO_RESPONSE
86 from a host or gateway.
94 and then an arbitrary number of
96 bytes used to fill out the packet.
97 The options are as follows:
98 .Bl -tag -width indent
104 character when no packet is received before the next packet
106 To cater for round-trip times that are longer than the interval
107 between transmissions, further missing packets cause a bell only
108 if the maximum number of unreceived packets has increased.
114 character in the output when any packet is received.
115 This option is ignored
116 if other format options are present.
118 Add an 802.1p Ethernet Priority Code Point when sending a packet.
119 0..7 uses that specific PCP, -1 uses the interface default PCP (or none).
126 If this option is not specified,
128 will operate until interrupted.
129 If this option is specified in conjunction with ping sweeps,
130 each sweep will consist of
134 Set the Don't Fragment bit.
138 option on the socket being used.
141 Outputs packets as fast as they come back or one hundred times per second,
147 is printed, while for every
149 received a backspace is printed.
150 This provides a rapid display of how many packets are being dropped.
151 Only the super-user may use this option.
153 This can be very hard on a network and should be used with caution.
155 .It Fl G Ar sweepmaxsize
156 Specify the maximum size of
158 payload when sending sweeping pings.
159 This option is required for ping sweeps.
160 .It Fl g Ar sweepminsize
163 payload to start with when sending sweeping pings.
164 The default value is 0.
167 Try to do a reverse DNS lookup when displaying addresses.
168 This is the opposite of the
171 .It Fl h Ar sweepincrsize
172 Specify the number of bytes to increment the size of
175 each sweep when sending sweeping pings.
176 The default value is 1.
178 Source multicast packets with the given interface address.
179 This flag only applies if the ping destination is a multicast address.
184 .Em between sending each packet .
185 The default is to wait for one second between each packet.
186 The wait time may be fractional, but only the super-user may specify
187 values less than 1 second.
188 This option is incompatible with the
192 Suppress loopback of multicast packets.
193 This flag only applies if the ping destination is a multicast address.
199 sends that many packets as fast as possible before falling into its normal
201 Only the super-user may use this option.
202 .It Fl M Cm mask | time
211 print the netmask of the remote machine.
213 .Va net.inet.icmp.maskrepl
214 MIB variable to enable
217 .Va net.inet.icmp.maskfake
218 if you want to override the netmask in the response.
221 print the origination, reception and transmission timestamps.
223 .Va net.inet.icmp.tstamprepl
224 MIB variable to enable or disable
225 .Dv ICMP_TSTAMPREPLY .
227 Set the IP Time To Live for outgoing packets.
228 If not specified, the kernel uses the value of the
233 No attempt will be made to lookup symbolic names for host addresses.
234 This is the opposite of
236 and it is the default behavior.
238 Exit successfully after receiving one reply packet.
241 specifies IPsec policy for the ping session.
242 For details please refer to
245 .Xr ipsec_set_policy 3 .
247 You may specify up to 16
249 bytes to fill out the packet you send.
250 This is useful for diagnosing data-dependent problems in a network.
253 will cause the sent packet to be filled with all
256 Somewhat quiet output.
258 display ICMP error messages that are in response to our query messages.
261 flag was required to display such errors, but
263 displays all ICMP error messages.
264 On a busy machine, this output can be overbearing.
269 prints out any ICMP error messages caused by its own ECHO_REQUEST
273 Nothing is displayed except the summary lines at startup time and
282 the route buffer on returned packets.
283 Note that the IP header is only large enough for nine such routes;
286 command is usually better at determining the route packets take to a
287 particular destination.
288 If more routes come back than should, such as due to an illegal spoofed
289 packet, ping will print the route list and then truncate it at the correct
291 Many hosts ignore or discard the
295 Bypass the normal routing tables and send directly to a host on an attached
297 If the host is not on a directly-attached network, an error is returned.
298 This option can be used to ping a local host through an interface
299 that has no route through it
300 (e.g., after the interface was dropped by
303 Use the following IP address as the source address in outgoing packets.
304 On hosts with more than one IP address, this option can be used to
305 force the source address to be something other than the IP address
306 of the interface the probe packet is sent on.
308 is not one of this machine's interface addresses, an error is
309 returned and nothing is sent.
310 .It Fl s Ar packetsize
311 Specify the number of data bytes to be sent.
312 The default is 56, which translates into 64
314 data bytes when combined
318 Only the super-user may specify values more than default.
319 This option cannot be used with ping sweeps.
321 Set the IP Time To Live for multicasted packets.
322 This flag only applies if the ping destination is a multicast address.
324 Specify a timeout, in seconds, before ping exits regardless of how
325 many packets have been received.
331 that are received are listed.
333 Time in milliseconds to wait for a reply for each packet sent.
334 If a reply arrives later, the packet is not printed as replied, but
335 considered as replied when calculating statistics.
337 Use the specified type of service.
342 for fault isolation, it should first be run on the local host, to verify
343 that the local network interface is up and running.
344 Then, hosts and gateways further and further away should be
346 Round-trip times and packet loss statistics are computed.
347 If duplicate packets are received, they are not included in the packet
348 loss calculation, although the round trip time of these packets is used
349 in calculating the round-trip time statistics.
350 When the specified number of packets have been sent
352 or if the program is terminated with a
354 a brief summary is displayed, showing the number of packets sent and
355 received, and the minimum, mean, maximum, and standard deviation of
356 the round-trip times.
366 signal, the current number of packets sent and received, and the
367 minimum, mean, and maximum of the round-trip times will be written to
368 the standard error output.
370 This program is intended for use in network testing, measurement and
372 Because of the load it can impose on the network, it is unwise to use
374 during normal operations or from automated scripts.
375 .Sh ICMP PACKET DETAILS
376 An IP header without options is 20 bytes.
380 packet contains an additional 8 bytes worth of
382 header followed by an arbitrary amount of data.
385 is given, this indicated the size of this extra piece of data
387 Thus the amount of data received inside of an IP packet of type
390 will always be 8 bytes more than the requested data space
395 If the data space is at least eight bytes large,
397 uses the first eight bytes of this space to include a timestamp which
398 it uses in the computation of round trip times.
399 If less than eight bytes of pad are specified, no round trip times are
401 .Sh DUPLICATE AND DAMAGED PACKETS
404 utility will report duplicate and damaged packets.
405 Duplicate packets should never occur when pinging a unicast address,
406 and seem to be caused by
407 inappropriate link-level retransmissions.
408 Duplicates may occur in many situations and are rarely
410 a good sign, although the presence of low levels of duplicates may not
411 always be cause for alarm.
412 Duplicates are expected when pinging a broadcast or multicast address,
413 since they are not really duplicates but replies from different hosts
416 Damaged packets are obviously serious cause for alarm and often
417 indicate broken hardware somewhere in the
419 packet's path (in the network or in the hosts).
420 .Sh TRYING DIFFERENT DATA PATTERNS
423 layer should never treat packets differently depending on the data
424 contained in the data portion.
425 Unfortunately, data-dependent problems have been known to sneak into
426 networks and remain undetected for long periods of time.
427 In many cases the particular pattern that will have problems is something
428 that does not have sufficient
430 such as all ones or all zeros, or a pattern right at the edge, such as
433 necessarily enough to specify a data pattern of all zeros (for example)
434 on the command line because the pattern that is of interest is
435 at the data link level, and the relationship between what you type and
436 what the controllers transmit can be complicated.
438 This means that if you have a data-dependent problem you will probably
439 have to do a lot of testing to find it.
440 If you are lucky, you may manage to find a file that either
442 be sent across your network or that takes much longer to transfer than
443 other similar length files.
444 You can then examine this file for repeated patterns that you can test
452 value of an IP packet represents the maximum number of IP routers
453 that the packet can go through before being thrown away.
454 In current practice you can expect each router in the Internet to decrement
457 field by exactly one.
461 specification recommends setting the
465 packets to 64, but many systems use smaller values
471 The maximum possible value of this field is 255, and most
477 .Tn ICMP ECHO_REQUEST
479 This is why you will find you can
481 some hosts, but not reach them with
488 prints the ttl value from the packet it receives.
489 When a remote system receives a ping packet, it can do one of three things
492 field in its response:
495 Not change it; this is what
497 systems did before the
502 value in the received packet will be 255 minus the
503 number of routers in the round-trip path.
505 Set it to 255; this is what current
510 value in the received packet will be 255 minus the
511 number of routers in the path
519 Set it to some other value.
520 Some machines use the same value for
522 packets that they use for
524 packets, for example either 30 or 60.
525 Others may use completely wild values.
530 utility exits with one of the following values:
531 .Bl -tag -width indent
533 At least one response was heard from the specified
536 The transmission was successful but no responses were received.
539 These values are defined in
556 utility was written by
558 while at the US Army Ballistics
561 Many Hosts and Gateways ignore the
565 The maximum IP header length is too small for options like
567 to be completely useful.
569 not much that can be done about this, however.
571 Flood pinging is not recommended in general, and flood pinging the
572 broadcast address should only be done under very controlled conditions.
576 option is not worth much on busy hosts.
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