ping6 -- send ICMPv6 ECHO_REQUEST packets to network hosts
ping6 [-dfHmnNqtvwW] [-a addrtype] [-b bufsiz] [-c count] [-g gateway]
[-h hoplimit] [-I interface] [-i wait] [-l preload] [-p pattern]
[-P policy] [-S sourceaddr] [-s packetsize] [hops ...] host
The ping6 command 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:
Generate ICMPv6 Node Information Node Addresses query, rather
than echo-request. addrtype must be a string constructed of the
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
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.
Set socket buffer size.
Stop after sending (and receiving) count ECHO_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. This can be very hard on a net-
work and should be used with caution.
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 ping6
command 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 linklocal/site-local
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.
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.
-m By default, ping6 asks the kernel to fragment packets to fit into
the minimum IPv6 MTU. -m 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
-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.
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.
-q Quiet output. Nothing is displayed except the summary lines at
startup time and when finished.
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.
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 ping6 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, maximum, mean, and standard deviation of
the round-trip times.
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 ping6 during normal operations or from automated scripts.
DUPLICATE AND DAMAGED PACKETS [Toc] [Back]
The ping6 command 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 ping6 packet's path (in the network or
in the hosts).
TRYING DIFFERENT DATA PATTERNS [Toc] [Back]
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 ping6.
ping6 command returns 0 on success (the host is alive), and non-zero if
the arguments are incorrect or the host is not responding.
Normally, ping6 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
ping6 -w ff02::1%wi0
The following will probe addresses assigned to the destination node,
ping6 -a agl dst.foo.com
netstat(1), icmp6(4), inet6(4), ip6(4), ifconfig(8), ping(8), routed(8),
A. Conta and S. Deering, Internet Control Message Protocol (ICMPv6) for
the Internet Protocol Version 6 (IPv6) Specification, RFC2463, December
Matt Crawford, IPv6 Node Information Queries, draft-ietf-ipngwg-icmpname-lookups-09.txt,
May 2002, work in progress material.
The ping(8) command appeared in 4.3BSD. The ping6 command 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 FreeBSD 4.0
ping6 is intentionally separate from ping(8).
There have been many discussions on why we separate ping6 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
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.
FreeBSD 5.2.1 May 17, 1998 FreeBSD 5.2.1 [ Back ]