The
utility uses the
ICMPv6
protocol's mandatory
ICMP6_ECHO_REQUEST
datagram to elicit an
ICMP6_ECHO_REPLY
from a host or gateway.
ICMP6_ECHO_REQUEST
datagrams (``pings'') have an IPv6 header,
and
ICMPv6
header formatted as documented in RFC2463.
The options are as follows:
-a addrtype
Generate ICMPv6 Node Information Node Addresses query, rather than echo-request.
addrtype
must be a string constructed of the following characters.
a
requests unicast addresses from all of the responder's interfaces.
If the character is omitted,
only those addresses which belong to the interface which has the
responder's address are requests.
c
requests responder's IPv4-compatible and IPv4-mapped addresses.
g
requests responder's global-scope addresses.
s
requests responder's site-local addresses.
l
requests responder's link-local addresses.
A
requests responder's anycast addresses.
Without this character, the responder will return unicast addresses only.
With this character, the responder will return anycast addresses only.
Note that the specification does not specify how to get responder's
anycast addresses.
This is an experimental option.
-b bufsiz
Set socket buffer size.
-c count
Stop after sending
(and receiving)
countECHO_RESPONSE
packets.
-d
Set the
SO_DEBUG
option on the socket being used.
-f
Flood ping.
Outputs packets as fast as they come back or one hundred times per second,
whichever is more.
For every
ECHO_REQUEST
sent a period
``.''
is printed, while for every
ECHO_REPLY
received a backspace is printed.
This provides a rapid display of how many packets are being dropped.
Only the super-user may use this option.
Bf -emphasis
This can be very hard on a network and should be used with caution.
Ef
-g gateway
Specifies to use
gateway
as the next hop to the destination.
The gateway must be a neighbor of the sending node.
-H
Specifies to try reverse-lookup of IPv6 addresses.
The
utility does not try reverse-lookup unless the option is specified.
-h hoplimit
Set the IPv6 hoplimit.
-I interface
Source packets with the given interface address.
This flag applies if the ping destination is a multicast address,
or link-local/site-local unicast address.
-i wait
Wait
wait
seconds
between sending each packet
The default is to wait for one second between each packet.
This option is incompatible with the
-f
option.
-l preload
If
preload
is specified,
sends that many packets as fast as possible before falling into its normal
mode of behavior.
Only the super-user may use this option.
-m
By default,
asks the kernel to fragment packets to fit into the minimum IPv6 MTU.
The
-m
option
will suppress the behavior in the following two levels:
when the option is specified once, the behavior will be disabled for
unicast packets.
When the option is more than once, it will be disabled for both
unicast and multicast packets.
-n
Numeric output only.
No attempt will be made to lookup symbolic names from addresses in the reply.
-N
Probe node information multicast group
(ff02::2:xxxx:xxxx
)
host
must be string hostname of the target
(must not be a numeric IPv6 address).
Node information multicast group will be computed based on given
host
and will be used as the final destination.
Since node information multicast group is a link-local multicast group,
outgoing interface needs to be specified by
-I
option.
-o
Exit successfully after receiving one reply packet.
-p pattern
You may specify up to 16
``pad''
bytes to fill out the packet you send.
This is useful for diagnosing data-dependent problems in a network.
For example,
``-p ff
''
will cause the sent packet to be filled with all
ones.
-P policy
policy
specifies IPsec policy to be used for the probe.
-q
Quiet output.
Nothing is displayed except the summary lines at startup time and
when finished.
-r
Audible.
Include a bell
( ASCII
0x07)
character in the output when any packet is received.
-R
Audible.
Output a bell
( ASCII
0x07)
character when no packet is received before the next packet
is transmitted.
To cater for round-trip times that are longer than the interval
between transmissions, further missing packets cause a bell only
if the maximum number of unreceived packets has increased.
-S sourceaddr
Specifies the source address of request packets.
The source address must be one of the unicast addresses of the sending node,
and must be numeric.
-s packetsize
Specifies the number of data bytes to be sent.
The default is 56, which translates into 64
ICMP
data bytes when combined
with the 8 bytes of
ICMP
header data.
You may need to specify
-b
as well to extend socket buffer size.
-t
Generate ICMPv6 Node Information supported query types query,
rather than echo-request.
-s
has no effect if
-t
is specified.
-v
Verbose output.
ICMP
packets other than
ECHO_RESPONSE
that are received are listed.
-w
Generate ICMPv6 Node Information DNS Name query, rather than echo-request.
-s
has no effect if
-w
is specified.
-W
Same as
-w
but with old packet format based on 03 draft.
This option is present for backward compatibility.
-s
has no effect if
-w
is specified.
hops
IPv6 addresses for intermediate nodes,
which will be put into type 0 routing header.
host
IPv6 address of the final destination node.
When using
for fault isolation, it should first be run on the local host, to verify
that the local network interface is up and running.
Then, hosts and gateways further and further away should be
``pinged''
Round-trip times and packet loss statistics are computed.
If duplicate packets are received, they are not included in the packet
loss calculation, although the round trip time of these packets is used
in calculating the round-trip time statistics.
When the specified number of packets have been sent
(and received)
or if the program is terminated with a
SIGINT
a brief summary is displayed, showing the number of packets sent and
received, and the minimum, mean, maximum, and standard deviation of
the round-trip times.
If
receives a
SIGINFO
(see the
status
argument for
stty(1))
signal, the current number of packets sent and received, and the
minimum, mean, maximum, and standard deviation of the round-trip times
will be written to the standard output in the same format as the
standard completion message.
This program is intended for use in network testing, measurement and
management.
Because of the load it can impose on the network, it is unwise to use
during normal operations or from automated scripts.
DUPLICATE AND DAMAGED PACKETS
The
utility will report duplicate and damaged packets.
Duplicate packets should never occur when pinging a unicast address,
and seem to be caused by
inappropriate link-level retransmissions.
Duplicates may occur in many situations and are rarely
(if ever)
a good sign, although the presence of low levels of duplicates may not
always be cause for alarm.
Duplicates are expected when pinging a broadcast or multicast address,
since they are not really duplicates but replies from different hosts
to the same request.
Damaged packets are obviously serious cause for alarm and often
indicate broken hardware somewhere in the
packet's path
(in the network or in the hosts).
TRYING DIFFERENT DATA PATTERNS
The
(inter)network
layer should never treat packets differently depending on the data
contained in the data portion.
Unfortunately, data-dependent problems have been known to sneak into
networks and remain undetected for long periods of time.
In many cases the particular pattern that will have problems is something
that does not have sufficient
``transitions''
such as all ones or all zeros, or a pattern right at the edge, such as
almost all zeros.
It is not
necessarily enough to specify a data pattern of all zeros (for example)
on the command line because the pattern that is of interest is
at the data link level, and the relationship between what you type and
what the controllers transmit can be complicated.
This means that if you have a data-dependent problem you will probably
have to do a lot of testing to find it.
If you are lucky, you may manage to find a file that either
cannot
be sent across your network or that takes much longer to transfer than
other similar length files.
You can then examine this file for repeated patterns that you can test
using the
-p
option of
.
EXIT STATUS
The
utility returns 0 on success (the host is alive),
2 if the transmission was successful but no responses were received,
any other non-zero value if the arguments are incorrect or
another error has occured.
EXAMPLES
Normally,
works just like
ping(8)
would work; the following will send ICMPv6 echo request to
dst.foo.com
ping6 -n dst.foo.com
The following will probe hostnames for all nodes on the network link attached to
wi0
interface.
The address
ff02::1
is named the link-local all-node multicast address, and the packet would
reach every node on the network link.
ping6 -w ff02::1%wi0
The following will probe addresses assigned to the destination node,
dst.foo.com
A. Conta
S. Deering
"Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification"
RFC2463
December 1998
Matt Crawford
"IPv6 Node Information Queries"
draft-ietf-ipngwg-icmp-name-lookups-09.txt
May 2002
work in progress material
HISTORY
The
ping(8)
utility appeared in
BSD 4.3
The
utility with IPv6 support first appeared in the WIDE Hydrangea IPv6
protocol stack kit.
IPv6 and IPsec support based on the KAME Project
(http://www.kame.net/
)
stack was initially integrated into
Fx 4.0 .
BUGS
The
utility
is intentionally separate from
ping(8).
There have been many discussions on why we separate
and
ping(8).
Some people argued that it would be more convenient to uniform the
ping command for both IPv4 and IPv6.
The followings are an answer to the request.
From a developer's point of view:
since the underling raw sockets API is totally different between IPv4
and IPv6, we would end up having two types of code base.
There would actually be less benefit to uniform the two commands
into a single command from the developer's standpoint.
From an operator's point of view: unlike ordinary network applications
like remote login tools, we are usually aware of address family when using
network management tools.
We do not just want to know the reachability to the host, but want to know the
reachability to the host via a particular network protocol such as
IPv6.
Thus, even if we had a unified
ping(8)
command for both IPv4 and IPv6, we would usually type a
-6
or
-4
option (or something like those) to specify the particular address family.
This essentially means that we have two different commands.
