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ping6(8)

NAME

     ping6 -- send ICMPv6 ECHO_REQUEST packets to network hosts

SYNOPSIS

     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

DESCRIPTION

     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
		     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) 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.

     -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-
	     fied.

     -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.

     -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.

     -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

     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-
     sage.

     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.

DUPLICATE AND DAMAGED PACKETS

     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).

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 ping6.

	   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.

	   ping6 -a agl dst.foo.com

SEE ALSO

     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
     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 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 (http://www.kame.net/)
     stack was initially integrated into FreeBSD 4.0.

BUGS

     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
     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 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 5.4			 May 17, 1998			   FreeBSD 5.4

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