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PING(8)                                    System Manager's Manual: iputils                                   PING(8)

       ping - send ICMP ECHO_REQUEST to network hosts

       ping  [-aAbBdDfhLnOqrRUvV46] [-c count] [-F flowlabel] [-i interval] [-I interface] [-l preload] [-m mark] [-M
       pmtudisc_option] [-N nodeinfo_option] [-w deadline] [-W timeout] [-p pattern] [-Q  tos]  [-s  packetsize]  [-S
       sndbuf] [-t ttl] [-T timestamp option] [hop ...] destination

       ping  uses  the ICMP protocol's mandatory ECHO_REQUEST datagram to elicit an ICMP ECHO_RESPONSE from a host or
       gateway.  ECHO_REQUEST datagrams (``pings'') have an IP and ICMP header, followed by a struct timeval and then
       an arbitrary number of ``pad'' bytes used to fill out the packet.

       ping works with both IPv4 and IPv6. Using only one of them explicitly can be enforced by specifying -4 or -6.

       ping  can  also  send  IPv6 Node Information Queries (RFC4620).  Intermediate hops may not be allowed, because
       IPv6 source routing was deprecated (RFC5095).

       -4     Use IPv4 only.

       -6     Use IPv6 only.

       -a     Audible ping.

       -A     Adaptive ping. Interpacket interval adapts to round-trip time, so that effectively not  more  than  one
              (or  more,  if  preload is set) unanswered probe is present in the network. Minimal interval is 200msec
              for not super-user.  On networks with low rtt this mode is essentially equivalent to flood mode.

       -b     Allow pinging a broadcast address.

       -B     Do not allow ping to change source address of probes.  The address is bound to one selected  when  ping

       -c count
              Stop  after  sending  count ECHO_REQUEST packets. With deadline option, ping waits for count ECHO_REPLY
              packets, until the timeout expires.

       -d     Set the SO_DEBUG option on the socket being used.  Essentially, this socket option is not used by Linux

       -D     Print timestamp (unix time + microseconds as in gettimeofday) before each line.

       -f     Flood ping. For every ECHO_REQUEST sent a period ``.'' is printed, while for ever ECHO_REPLY received a
              backspace is printed.  This provides a rapid display of how many packets are being dropped.  If  inter‐
              val is not given, it sets interval to zero and outputs packets as fast as they come back or one hundred
              times per second, whichever is more.  Only the super-user may use this option with zero interval.

       -F flow label
              IPv6 only.  Allocate and set 20 bit flow label (in hex) on echo request packets.   If  value  is  zero,
              kernel allocates random flow label.

       -h     Show help.

       -i interval

              select preload more than 3.

       -L     Suppress  loopback of multicast packets.  This flag only applies if the ping destination is a multicast

       -m mark
              use mark to tag the packets going out. This is useful for variety of reasons within the kernel such  as
              using policy routing to select specific outbound processing.

       -M pmtudisc_opt
              Select  Path  MTU  Discovery  strategy.  pmtudisc_option may be either do (prohibit fragmentation, even
              local one), want (do PMTU discovery, fragment locally when packet size is large), or dont (do  not  set
              DF flag).

       -N nodeinfo_option
              IPv6 only.  Send ICMPv6 Node Information Queries (RFC4620), instead of Echo Request.  CAP_NET_RAW capa‐
              bility is required.

              help   Show help for NI support.

              name   Queries for Node Names.

              ipv6   Queries for IPv6 Addresses. There are several IPv6 specific flags.

                            Request IPv6 global-scope addresses.

                            Request IPv6 site-local addresses.

                            Request IPv6 link-local addresses.

                            Request IPv6 addresses on other interfaces.

              ipv4   Queries for IPv4 Addresses.  There is one IPv4 specific flag.

                            Request IPv4 addresses on other interfaces.

                     IPv6 subject address.

                     IPv4 subject address.

                     Subject name.  If it contains more than one dot, fully-qualified domain name is assumed.

                     Subject name.  Fully-qualified domain name is always assumed.

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

              In RFC2474, these fields are interpreted as 8-bit Differentiated Services (DS), consisting of: bits 0-1
              (2 lowest bits) of separate data, and bits 2-7 (highest 6 bits) of  Differentiated  Services  Codepoint
              (DSCP).  In RFC2481 and RFC3168, bits 0-1 are used for ECN.

              Historically  (RFC1349,  obsoleted  by  RFC2474),  these  were  interpreted  as: bit 0 (lowest bit) for
              reserved (currently being redefined as congestion control), 1-4 for Type of Service and bits 5-7 (high‐
              est bits) for Precedence.

       -r     Bypass  the normal routing tables and send directly to a host on an attached interface.  If the host is
              not on a directly-attached network, an error is returned.  This option can be used to ping a local host
              through an interface that has no route through it provided the option -I is also used.

       -R     ping only.  Record route.  Includes the RECORD_ROUTE option in the ECHO_REQUEST packet and displays the
              route buffer on returned packets.  Note that the IP header is only large enough for nine  such  routes.
              Many hosts ignore or discard this option.

       -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.

       -S sndbuf
              Set socket sndbuf. If not specified, it is selected to buffer not more than one packet.

       -t ttl ping only.  Set the IP Time to Live.

       -T timestamp option
              Set special IP timestamp options.  timestamp option may be either tsonly (only  timestamps),  tsandaddr
              (timestamps and addresses) or tsprespec host1 [host2 [host3 [host4]]] (timestamp prespecified hops).

       -U     Print  full  user-to-user  latency  (the  old behaviour). Normally ping prints network round trip time,
              which can be different f.e. due to DNS failures.

       -v     Verbose output.

       -V     Show version and exit.

       -w deadline
              Specify a timeout, in seconds, before ping exits regardless of how  many  packets  have  been  sent  or
              received.  In  this  case  ping does not stop after count packet are sent, it waits either for deadline
              expire or until count probes are answered or for some error notification from network.

       -W timeout
              Time to wait for a response, in seconds. The option affects only timeout in absence of  any  responses,
              otherwise ping waits for two RTTs.

       When  using  ping for fault isolation, it should first be run on the local host, to verify that the local net‐
       work 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 calculation, although the round trip time of these packets is used in  calculating
       the minimum/average/maximum round-trip time numbers.  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. Shorter current statis‐
       tics can be obtained without termination of process with signal SIGQUIT.

       ICMP ECHO_REPLY will always be 8 bytes more than the requested data space (the ICMP header).

       If the data space is at least of size of struct timeval ping uses the beginning bytes of this space to include
       a timestamp which it uses in the computation of round trip times.  If the data space is shorter, no round trip
       times are given.

       ping will report duplicate and damaged packets.  Duplicate packets should never occur, 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.

       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).

       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
       doesn't have sufficient ``transitions'', such as all ones or all zeros, or a pattern right at the  edge,  such
       as  almost all zeros.  It isn't 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 can't 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 ping.

       The TTL value of an IP packet represents the maximum number of IP routers  that  the  packet  can  go  through
       before being thrown away.  In current practice you can expect each router in the Internet to decrement the TTL
       field by exactly one.

       The TCP/IP specification states that the TTL field for TCP packets should be set to 60, but many  systems  use
       smaller values (4.3 BSD uses 30, 4.2 used 15).

       The  maximum possible value of this field is 255, and most Unix systems set the TTL field of ICMP ECHO_REQUEST
       packets to 255.  This is why you will find you can ``ping'' some hosts, but not reach them with  telnet(1)  or

       In  normal  operation  ping prints the TTL value from the packet it receives.  When a remote system receives a
       ping packet, it can do one of three things with the TTL field in its response:

       · Not change it; this is what Berkeley Unix systems did before the 4.3BSD Tahoe release. In this case the  TTL
         value in the received packet will be 255 minus the number of routers in the round-trip path.

       · Set  it  to  255; this is what current Berkeley Unix systems do.  In this case the TTL value in the received
         packet will be 255 minus the number of routers in the path from the remote system to the pinging host.

       · Set it to some other value. Some machines use the same value for ICMP packets that they use for TCP packets,
         for example either 30 or 60.  Others may use completely wild values.

       · Many Hosts and Gateways ignore the RECORD_ROUTE option.

       The version described here is its descendant specific to Linux.

       As  of  version  s20150815,  the ping6 binary doesn't exist anymore.  It has been merged into ping. Creating a
       symlink named ping6 pointing to ping will result in the same funcionality as before.

       ping requires CAP_NET_RAW capability to be executed 1) if the program is used for  non-echo  queries  (See  -N
       option),  or 2) if kernel does not support non-raw ICMP sockets, or 3) if the user is not allowed to create an
       ICMP echo socket.  The program may be used as set-uid root.

       ping  is  part  of  iputils  package  and  the  latest   versions   are    available   in   source   form   at

iputils-160308                                                                                                PING(8)