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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
122 Prohibit the socket from using the cellular network interface.
129 If this option is not specified,
131 will operate until interrupted.
132 If this option is specified in conjunction with ping sweeps,
133 each sweep will consist of
137 Set the Don't Fragment bit.
141 option on the socket being used.
144 Outputs packets as fast as they come back or one hundred times per second,
150 is printed, while for every
152 received a backspace is printed.
153 This provides a rapid display of how many packets are being dropped.
154 Only the super-user may use this option.
156 This can be very hard on a network and should be used with caution.
158 .It Fl G Ar sweepmaxsize
159 Specify the maximum size of
161 payload when sending sweeping pings.
162 This option is required for ping sweeps.
163 .It Fl g Ar sweepminsize
166 payload to start with when sending sweeping pings.
167 The default value is 0.
168 .It Fl h Ar sweepincrsize
169 Specify the number of bytes to increment the size of
172 each sweep when sending sweeping pings. The default value is 1.
174 Source multicast packets with the given interface address.
175 This flag only applies if the ping destination is a multicast address.
180 .Em between sending each packet .
181 The default is to wait for one second between each packet.
182 The wait time may be fractional, but only the super-user may specify
183 values less than 1 second.
184 This option is incompatible with the
188 Suppress loopback of multicast packets.
189 This flag only applies if the ping destination is a multicast address.
195 sends that many packets as fast as possible before falling into its normal
197 Only the super-user may use this option.
198 .It Fl M Cm mask | time
207 print the netmask of the remote machine.
209 .Va net.inet.icmp.maskrepl
210 MIB variable to enable
214 print the origination, reception and transmission timestamps.
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 This option cannot be used with ping sweeps.
306 Set the IP Time To Live for multicasted packets.
307 This flag only applies if the ping destination is a multicast address.
309 Specify a timeout, in seconds, before ping exits regardless of how
310 many packets have been received.
316 that are received are listed.
318 Time in milliseconds to wait for a reply for each packet sent.
319 If a reply arrives later, the packet is not printed as replied, but
320 considered as replied when calculating statistics.
322 Use the specified type of service.
327 for fault isolation, it should first be run on the local host, to verify
328 that the local network interface is up and running.
329 Then, hosts and gateways further and further away should be
331 Round-trip times and packet loss statistics are computed.
332 If duplicate packets are received, they are not included in the packet
333 loss calculation, although the round trip time of these packets is used
334 in calculating the round-trip time statistics.
335 When the specified number of packets have been sent
337 or if the program is terminated with a
339 a brief summary is displayed, showing the number of packets sent and
340 received, and the minimum, mean, maximum, and standard deviation of
341 the round-trip times.
351 signal, the current number of packets sent and received, and the
352 minimum, mean, and maximum of the round-trip times will be written to
353 the standard error output.
355 This program is intended for use in network testing, measurement and
357 Because of the load it can impose on the network, it is unwise to use
359 during normal operations or from automated scripts.
360 .Sh ICMP PACKET DETAILS
361 An IP header without options is 20 bytes.
365 packet contains an additional 8 bytes worth of
367 header followed by an arbitrary amount of data.
370 is given, this indicated the size of this extra piece of data
372 Thus the amount of data received inside of an IP packet of type
375 will always be 8 bytes more than the requested data space
380 If the data space is at least eight bytes large,
382 uses the first eight bytes of this space to include a timestamp which
383 it uses in the computation of round trip times.
384 If less than eight bytes of pad are specified, no round trip times are
386 .Sh DUPLICATE AND DAMAGED PACKETS
389 utility will report duplicate and damaged packets.
390 Duplicate packets should never occur when pinging a unicast address,
391 and seem to be caused by
392 inappropriate link-level retransmissions.
393 Duplicates may occur in many situations and are rarely
395 a good sign, although the presence of low levels of duplicates may not
396 always be cause for alarm.
397 Duplicates are expected when pinging a broadcast or multicast address,
398 since they are not really duplicates but replies from different hosts
401 Damaged packets are obviously serious cause for alarm and often
402 indicate broken hardware somewhere in the
404 packet's path (in the network or in the hosts).
405 .Sh TRYING DIFFERENT DATA PATTERNS
408 layer should never treat packets differently depending on the data
409 contained in the data portion.
410 Unfortunately, data-dependent problems have been known to sneak into
411 networks and remain undetected for long periods of time.
412 In many cases the particular pattern that will have problems is something
413 that does not have sufficient
415 such as all ones or all zeros, or a pattern right at the edge, such as
418 necessarily enough to specify a data pattern of all zeros (for example)
419 on the command line because the pattern that is of interest is
420 at the data link level, and the relationship between what you type and
421 what the controllers transmit can be complicated.
423 This means that if you have a data-dependent problem you will probably
424 have to do a lot of testing to find it.
425 If you are lucky, you may manage to find a file that either
427 be sent across your network or that takes much longer to transfer than
428 other similar length files.
429 You can then examine this file for repeated patterns that you can test
437 value of an IP packet represents the maximum number of IP routers
438 that the packet can go through before being thrown away.
439 In current practice you can expect each router in the Internet to decrement
442 field by exactly one.
446 specification recommends setting the
450 packets to 64, but many systems use smaller values
456 The maximum possible value of this field is 255, and most
462 .Tn ICMP ECHO_REQUEST
464 This is why you will find you can
466 some hosts, but not reach them with
473 prints the ttl value from the packet it receives.
474 When a remote system receives a ping packet, it can do one of three things
477 field in its response:
480 Not change it; this is what
482 systems did before the
487 value in the received packet will be 255 minus the
488 number of routers in the round-trip path.
490 Set it to 255; this is what current
495 value in the received packet will be 255 minus the
496 number of routers in the path
504 Set it to some other value.
505 Some machines use the same value for
507 packets that they use for
509 packets, for example either 30 or 60.
510 Others may use completely wild values.
515 utility returns an exit status of zero if at least one response was
516 heard from the specified
518 a status of two if the transmission was successful but no responses
519 were received; or another value
522 if an error occurred.
537 utility was written by
539 while at the US Army Ballistics
542 Many Hosts and Gateways ignore the
546 The maximum IP header length is too small for options like
548 to be completely useful.
550 not much that can be done about this, however.
552 Flood pinging is not recommended in general, and flood pinging the
553 broadcast address should only be done under very controlled conditions.
557 option is not worth much on busy hosts.
projects / apple / network_cmds.git / blob