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28 .\" @(#)ping.8 8.2 (Berkeley) 12/11/93
29 .\" $FreeBSD: src/sbin/ping/ping.8,v 1.51.8.2 2006/08/10 10:48:21 glebius Exp $
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 Bind the socket to interface
127 If this option is not specified,
129 will operate until interrupted.
130 If this option is specified in conjunction with ping sweeps,
131 each sweep will consist of
135 Set the Don't Fragment bit.
139 option on the socket being used.
142 Outputs packets as fast as they come back or one hundred times per second,
148 is printed, while for every
150 received a backspace is printed.
151 This provides a rapid display of how many packets are being dropped.
152 Only the super-user may use this option.
154 This can be very hard on a network and should be used with caution.
156 .It Fl G Ar sweepmaxsize
157 Specify the maximum size of
159 payload when sending sweeping pings.
160 This option is required for ping sweeps.
161 .It Fl g Ar sweepminsize
164 payload to start with when sending sweeping pings.
165 The default value is 0.
166 .It Fl h Ar sweepincrsize
167 Specify the number of bytes to increment the size of
170 each sweep when sending sweeping pings. The default value is 1.
172 Source multicast packets with the given interface address.
173 This flag only applies if the ping destination is a multicast address.
178 .Em between sending each packet .
179 The default is to wait for one second between each packet.
180 The wait time may be fractional, but only the super-user may specify
181 values less than 1 second.
182 This option is incompatible with the
186 Suppress loopback of multicast packets.
187 This flag only applies if the ping destination is a multicast address.
193 sends that many packets as fast as possible before falling into its normal
195 Only the super-user may use this option.
196 .It Fl M Cm mask | time
205 print the netmask of the remote machine.
207 .Va net.inet.icmp.maskrepl
208 MIB variable to enable
212 print the origination, reception and transmission timestamps.
214 Set the IP Time To Live for outgoing packets.
215 If not specified, the kernel uses the value of the
220 No attempt will be made to lookup symbolic names for host addresses.
222 Exit successfully after receiving one reply packet.
225 specifies IPsec policy for the ping session.
226 For details please refer to
229 .Xr ipsec_set_policy 3 .
231 You may specify up to 16
233 bytes to fill out the packet you send.
234 This is useful for diagnosing data-dependent problems in a network.
237 will cause the sent packet to be filled with all
240 Somewhat quiet output.
242 display ICMP error messages that are in response to our query messages.
245 flag was required to display such errors, but
247 displays all ICMP error messages.
248 On a busy machine, this output can be overbearing.
253 prints out any ICMP error messages caused by its own ECHO_REQUEST
257 Nothing is displayed except the summary lines at startup time and
266 the route buffer on returned packets.
267 Note that the IP header is only large enough for nine such routes;
270 command is usually better at determining the route packets take to a
271 particular destination.
272 If more routes come back than should, such as due to an illegal spoofed
273 packet, ping will print the route list and then truncate it at the correct
275 Many hosts ignore or discard the
279 Bypass the normal routing tables and send directly to a host on an attached
281 If the host is not on a directly-attached network, an error is returned.
282 This option can be used to ping a local host through an interface
283 that has no route through it
284 (e.g., after the interface was dropped by
287 Use the following IP address as the source address in outgoing packets.
288 On hosts with more than one IP address, this option can be used to
289 force the source address to be something other than the IP address
290 of the interface the probe packet is sent on.
292 is not one of this machine's interface addresses, an error is
293 returned and nothing is sent.
294 .It Fl s Ar packetsize
295 Specify the number of data bytes to be sent.
296 The default is 56, which translates into 64
298 data bytes when combined
302 This option cannot be used with ping sweeps.
304 Set the IP Time To Live for multicasted packets.
305 This flag only applies if the ping destination is a multicast address.
307 Specify a timeout, in seconds, before ping exits regardless of how
308 many packets have been received.
314 that are received are listed.
316 Time in milliseconds to wait for a reply for each packet sent.
317 If a reply arrives later, the packet is not printed as replied, but
318 considered as replied when calculating statistics.
320 Use the specified type of service.
325 for fault isolation, it should first be run on the local host, to verify
326 that the local network interface is up and running.
327 Then, hosts and gateways further and further away should be
329 Round-trip times and packet loss statistics are computed.
330 If duplicate packets are received, they are not included in the packet
331 loss calculation, although the round trip time of these packets is used
332 in calculating the round-trip time statistics.
333 When the specified number of packets have been sent
335 or if the program is terminated with a
337 a brief summary is displayed, showing the number of packets sent and
338 received, and the minimum, mean, maximum, and standard deviation of
339 the round-trip times.
349 signal, the current number of packets sent and received, and the
350 minimum, mean, and maximum of the round-trip times will be written to
351 the standard error output.
353 This program is intended for use in network testing, measurement and
355 Because of the load it can impose on the network, it is unwise to use
357 during normal operations or from automated scripts.
358 .Sh ICMP PACKET DETAILS
359 An IP header without options is 20 bytes.
363 packet contains an additional 8 bytes worth of
365 header followed by an arbitrary amount of data.
368 is given, this indicated the size of this extra piece of data
370 Thus the amount of data received inside of an IP packet of type
373 will always be 8 bytes more than the requested data space
378 If the data space is at least eight bytes large,
380 uses the first eight bytes of this space to include a timestamp which
381 it uses in the computation of round trip times.
382 If less than eight bytes of pad are specified, no round trip times are
384 .Sh DUPLICATE AND DAMAGED PACKETS
387 utility will report duplicate and damaged packets.
388 Duplicate packets should never occur when pinging a unicast address,
389 and seem to be caused by
390 inappropriate link-level retransmissions.
391 Duplicates may occur in many situations and are rarely
393 a good sign, although the presence of low levels of duplicates may not
394 always be cause for alarm.
395 Duplicates are expected when pinging a broadcast or multicast address,
396 since they are not really duplicates but replies from different hosts
399 Damaged packets are obviously serious cause for alarm and often
400 indicate broken hardware somewhere in the
402 packet's path (in the network or in the hosts).
403 .Sh TRYING DIFFERENT DATA PATTERNS
406 layer should never treat packets differently depending on the data
407 contained in the data portion.
408 Unfortunately, data-dependent problems have been known to sneak into
409 networks and remain undetected for long periods of time.
410 In many cases the particular pattern that will have problems is something
411 that does not have sufficient
413 such as all ones or all zeros, or a pattern right at the edge, such as
416 necessarily enough to specify a data pattern of all zeros (for example)
417 on the command line because the pattern that is of interest is
418 at the data link level, and the relationship between what you type and
419 what the controllers transmit can be complicated.
421 This means that if you have a data-dependent problem you will probably
422 have to do a lot of testing to find it.
423 If you are lucky, you may manage to find a file that either
425 be sent across your network or that takes much longer to transfer than
426 other similar length files.
427 You can then examine this file for repeated patterns that you can test
435 value of an IP packet represents the maximum number of IP routers
436 that the packet can go through before being thrown away.
437 In current practice you can expect each router in the Internet to decrement
440 field by exactly one.
444 specification recommends setting the
448 packets to 64, but many systems use smaller values
454 The maximum possible value of this field is 255, and most
460 .Tn ICMP ECHO_REQUEST
462 This is why you will find you can
464 some hosts, but not reach them with
471 prints the ttl value from the packet it receives.
472 When a remote system receives a ping packet, it can do one of three things
475 field in its response:
478 Not change it; this is what
480 systems did before the
485 value in the received packet will be 255 minus the
486 number of routers in the round-trip path.
488 Set it to 255; this is what current
493 value in the received packet will be 255 minus the
494 number of routers in the path
502 Set it to some other value.
503 Some machines use the same value for
505 packets that they use for
507 packets, for example either 30 or 60.
508 Others may use completely wild values.
513 utility returns an exit status of zero if at least one response was
514 heard from the specified
516 a status of two if the transmission was successful but no responses
517 were received; or another value
520 if an error occurred.
534 utility was written by
536 while at the US Army Ballistics
539 Many Hosts and Gateways ignore the
543 The maximum IP header length is too small for options like
545 to be completely useful.
547 not much that can be done about this, however.
549 Flood pinging is not recommended in general, and flood pinging the
550 broadcast address should only be done under very controlled conditions.
554 option is not worth much on busy hosts.
projects / apple / network_cmds.git / blob