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

NAME
     ping6 - send ICMPv6 ECHO_REQUEST packets to network hosts

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

DESCRIPTION
     ping6 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 all the responder's unicast addresses.  If the
		     charater is ommited, only those addresses which belong to
		     the interface which has the responder's address are re­
		     quests.
	     c	     requests responder's IPv4-compatible and IPv4-mapped ad­
		     dresses.
	     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.

     -H      Specifies to try reverse-lookup of IPv6 addresses.  The ping6
	     command does not try reverse-lookup unless the option is speci­
	     fied.

     -h hoplimit
	     Set the IPv6 hoplimit.

     -I interface
	     Source packets with the given interface address.  This flag ap­
	     plies if the ping destination is a multicast address, or link-lo­
	     cal/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, ping sends that many packets as fast as
	     possible before falling into its normal mode of behavior.	Only
	     the super-user may use this option.

     -n      Numeric output only.  No attempt will be made to lookup symbolic
	     names for host addresses.

     -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,
	     destination link 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.  -Q flag, ping6 prints out any ICMP error
	     messages caused by its own ECHO_REQUEST messages.

     -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      Make the kernel believe that the target host (or the first hop if
	     you specify hops) is reachable, by injecting upper-layer reacha­
	     bility confirmation hint.	The option is meaningful only if the
	     target host (or the first hop) is a neighbor.

     -S sourceaddr
	     Specifies the source address of request packets.  The source ad­
	     dress must be one of the unicast addresses of the sending node.
	     If the outgoing interface is specified by the -I option as well,
	     sourceaddr needs to be an address assigned to the specified in­
	     terface.

     -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.

     -v      Verbose output.  ICMP packets other than ECHO_RESPONSE that are
	     received are listed.

     -w      Generate ICMPv6 Node Information FQDN query, rather than echo-re­
	     quest.  -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 adddress 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, maximum, mean, and standard deviation of
     the round-trip times.

     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
     Ping6 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 pres­
     ence of low levels of duplicates may not always be cause for alarm.  Du­
     plicates 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 ping 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 .

RETURN VALUES
     ping6 returns 0 on success (the host is alive), and non-zero if the argu­
     ments are incorrect or the host is not responding.

SEE ALSO
     netstat(1),  ifconfig(8),	ping(8),  routed(8),  traceroute(8),  tracer­
     oute6(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-05.txt, October 22, 1999, work in progress material.

BUGS
     There have been many discussions on why we separate ping6(8) 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 re­
     quest.

     From a developer's point of view: since the underling API is totally dif­
     ferent 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 us­
     ing network management tools.  We do not just want to know the reachabil­
     ity to the host, but want to know the reachability to the host via a par­
     ticular 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 fami­
     ly.  This essentially means that we have two different commands.

HISTORY
     The ping command appeared in 4.3BSD. The ping6 command with IPv6 support
     first appeared in 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

BSD				 May 17, 1998				     4

NAME | SYNOPSIS | DESCRIPTION | DUPLICATE AND DAMAGED PACKETS | TRYING DIFFERENT DATA PATTERNS | RETURN VALUES | SEE ALSO | BUGS | HISTORY

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