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

NAME
     ping6 -- send ICMPv6 ECHO_REQUEST packets to network hosts

SYNOPSIS
     ping6 [-dfHmnNqRtvwW] [-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
     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 RFC 2463.  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
             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
             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.  -m will suppress the behavior in the fol-
             lowing two levels: when the option is specified once, the behav-
             ior will be disabled for unicast packets.  When the option is
             specified 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.

     -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,
             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, 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.
     Duplicates are expected when pinging a 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.

EXIT STATUS
     ping6 exits with 0 on success (the host is alive), and non-zero if the
     arguments are incorrect or the host is not responding.

EXAMPLES
     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
     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, RFC 2463, 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) command appeared in 4.3BSD.  The ping6 command with IPv6 sup-
     port first appeared in the WIDE Hydrangea IPv6 protocol stack kit.

BUGS
     ping6 is intentionally separate from ping(8).

NetBSD 5.0_STABLE                May 18, 2006                NetBSD 5.0_STABLE
