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PING6(8)		FreeBSD	System Manager's Manual		      PING6(8)

     ping6 -- send ICMPv6 ECHO_REQUEST packets to network hosts

     ping6 [-DdfHmnNoqrRtvwW] [-a addrtype] [-b	bufsiz]	[-c count]
	   [-g gateway]	[-h hoplimit] [-I interface] [-i wait] [-l preload]
	   [-P policy] [-p pattern] [-S	sourceaddr] [-s	packetsize] [hops ...]

     The ping6 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
	     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)	count ECHO_RESPONSE packets.

     -D	     Disable IPv6 fragmentation.

     -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.

     -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 ping6
	     utility does not try reverse-lookup unless	the option is speci-

     -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 incom-
	     patible with the -f option.

     -l	preload
	     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.  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	trans-
	     missions, further missing packets cause a bell only if the	maxi-
	     mum 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	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 calcula-
     tion, although the	round trip time	of these packets is used in calculat-
     ing 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	ping6 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 mes-

     This program is intended for use in network testing, measurement and man-
     agement.  Because of the load it can impose on the	network, it is unwise
     to	use ping6 during normal	operations or from automated scripts.

     The ping6 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 ping6 packet's 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
     -p	option of ping6.

     The ping6 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

     Normally, ping6 works just	like ping(8) would work; the following will
     send ICMPv6 echo request to

	   ping6 -n

     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,

	   ping6 -a agl

     netstat(1), icmp6(4), inet6(4), ip6(4), ifconfig(8), ping(8), routed(8),
     traceroute(8), traceroute6(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-icmp-
     name-lookups-09.txt, May 2002, work in progress material.

     The ping(8) utility appeared in 4.3BSD.  The ping6	utility	with IPv6 sup-
     port 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.

     The ping6 utility 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 reacha-
     bility 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	fam-
     ily.  This	essentially means that we have two different commands.

FreeBSD	9.2			April 20, 2010			   FreeBSD 9.2


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