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

     ping6 -- send ICMPv6 ECHO_REQUEST packets to network hosts

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

     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
                     character is omitted, only those addresses which belong
                     to the interface which has the responder's address are
             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      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-

     -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.

     -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, 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.

     -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
             address 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

     -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 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.

     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.
     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.

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

     Normally, ping6(8) 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
     network link.

           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),
     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-07.txt, August 2000, work in progress material.

     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

     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.

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