send ICMPv6 ECHO_REQUEST packets to network
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
- Generate ICMPv6 Node Information Node Addresses query, rather than
echo-request. addrtype must be a string
constructed of the following characters.
- 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.
- requests responder's IPv4-compatible and IPv4-mapped addresses.
- requests responder's global-scope addresses.
- requests responder's site-local addresses.
- requests responder's link-local addresses.
- 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.
- Set socket buffer size.
- Stop after sending (and receiving) count
- Disable IPv6 fragmentation.
- Set the
SO_DEBUG option on the socket
- 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.
This can be very hard on a network and should be used
- Specifies to use gateway as the next hop
to the destination. The gateway must be a neighbor of the sending
- Specifies to try reverse-lookup of IPv6 addresses. The
ping6 utility does not try
reverse-lookup unless the option is specified.
- Set the IPv6 hoplimit.
- Source packets with the given interface address. This flag applies if the
ping destination is a multicast address, or link-local/site-local unicast
- Wait wait seconds
between sending each packet. The default is
to wait for one second between each packet. This option is incompatible
- Time in milliseconds to wait for a reply for each packet sent. If a reply
arrives later, the packet is not printed as replied, but considered as
replied when calculating statistics.
- Specify a timeout, in seconds, before ping exits regardless of how many
packets have been received.
- If preload is specified,
ping6 sends that many packets as fast
as possible before falling into its normal mode of behavior. Only the
super-user may use this option.
- By default,
ping6 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.
- Numeric output only. No attempt will be made to lookup symbolic names from
addresses in the reply.
- Probe node information multicast group address
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
When specified twice, the address
ff02::2:xxxx:xxxx) is used instead. The former is
in RFC 4620, the latter is in an old Internet Draft
draft-ietf-ipngwg-icmp-name-lookup. Note that KAME-derived implementations
including FreeBSD use the latter.
- Exit successfully after receiving one reply packet.
- 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.
- policy specifies IPsec policy to be used
for the probe.
- Quiet output. Nothing is displayed except the summary lines at startup
time and when finished.
- Audible. Include a bell (ASCII 0x07) character in the output when any
packet is received.
- 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
- Specifies the source address of request packets. The source address must
be one of the unicast addresses of the sending node, and must be
- 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
as well to extend socket buffer size.
- Generate ICMPv6 Node Information supported query types query, rather than
-s has no effect if
-t is specified.
- Verbose output. ICMP packets other than ECHO_RESPONSE that are received
- Generate ICMPv6 Node Information DNS Name query, rather than echo-request.
-s has no effect if
-w is specified.
- 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.
- IPv6 addresses for intermediate nodes, which will be put into type 0
- IPv6 address of the final destination node.
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
, 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.
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
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
Damaged packets are obviously serious cause for alarm and often indicate broken
hardware somewhere in the
path (in the network or in the hosts).
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
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 occurred.
works just like
would work; the following will send ICMPv6 echo request to
The following will probe hostnames for all nodes on the network link attached to
interface. The address
is named the link-local all-node multicast
address, and the packet would reach every node on the network link.
The following will probe addresses assigned to the destination node,
A. Conta and
S. Deering, Internet Control
Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6)
IPv6 Node Information Queries,
May 2002, work in progress
utility appeared in 4.3BSD
utility with IPv6 support first
appeared in the WIDE Hydrangea IPv6 protocol stack kit.
IPv6 and IPsec support based on the KAME Project
) stack was initially
integrated into FreeBSD 4.0
utility is intentionally separate
There have been many discussions on why we separate
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
command for both IPv4 and IPv6, we would usually type a
option (or something like those) to specify the particular address family.
This essentially means that we have two different commands.