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           ping  [ -LRUbdfnqrvVaAB]  [ -c count]  [ -i interval]  [ -l preload]  [
           -p pattern]  [ -s packetsize]  [ -t ttl]  [ -w deadline]  [ -F  flowla-
           bel]  [ -I interface]  [ -M hint]  [ -Q tos]  [ -S sndbuf]  [ -T times-
           tamp option]  [ -W timeout]  [ 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


           -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 probes 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 starts.
           -c count
                  Stop  after  sending  count  ECHO_REQUEST packets. With deadline
                  option, ping waits for count ECHO_REPLY packets, until the time-
                  out expires.
           -d     Set  the SO_DEBUG option on the socket being used.  Essentially,
                  this socket option is not used by Linux kernel.
           -F flow label
                  Allocate and set 20 bit flow  label  on  echo  request  packets.
                  (Only  ping6).  If  value  is zero, kernel allocates random flow
           -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  interval is not given, it sets interval to
                  zero and outputs packets as fast as they come back or  one  hun-
                  dred  times  per second, whichever is more.  Only the super-user
                  may use this option with zero interval.
           -i interval
                  Wait interval seconds between sending each packet.  The  default
                  is  to  wait for one second between each packet normally, or not
                  if the ping destination is a multicast address.
           -n     Numeric output only.  No attempt will be made to lookup symbolic
                  names for host addresses.
           -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 tos Set Quality of Service -related bits in ICMP datagrams.  tos can
                  be either decimal or hex number.  Traditionally (RFC1349), these
                  have been interpreted as: 0 for reserved (currently being  rede-
                  fined  as  congestion  control), 1-4 for Type of Service and 5-7
                  for Precedence.  Possible settings for Type of Service are: min-
                  imal cost: 0x02, reliability: 0x04, throughput: 0x08, low delay:
                  0x10.  Multiple TOS bits should not be set simultaneously.  Pos-
                  sible settings for special Precedence range from priority (0x20)
                  to net control (0xe0).  You must be root (CAP_NET_ADMIN capabil-
                  ity) to use Critical or higher precedence value.  You cannot set
                  bit 0x01 (reserved) unless ECN has been enabled in  the  kernel.
                  In RFC2474, these fields has been redefined as 8-bit Differenti-
                  ated Services (DS), consisting of: bits  0-1  of  separate  data
                  (ECN  will  be  used, here), and bits 2-7 of Differentiated Ser-
                  vices Codepoint (DSCP).
           -q     Quiet output.  Nothing is displayed except the summary lines  at
                  startup time and when finished.
           -R     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.
           -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.
           -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 Set the IP Time to Live.
                  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 absense 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 network interface is up  and  run-
           ning.  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 dis-
           played. Shorter current statistics can be obtained without  termination
           of process with signal SIGQUIT.
           If  ping  does  not  receive any reply packets at all it will exit with
           code 1. If a packet count and deadline are both  specified,  and  fewer
           than  count  packets are received by the time the deadline has arrived,
           it will also exit with code 1.  On other error it exits  with  code  2.
           Otherwise  it exits with code 0. This makes it possible to use the exit
           code to see if a host is alive or not.
           This program is intended for use in network  testing,  measurement  and
           management.   Because  of  the load it can impose on the network, it is
           unwise to use ping during normal operations or from automated  scripts.


           An  IP header without options is 20 bytes.  An ICMP ECHO_REQUEST packet
           contains an additional 8 bytes worth of  ICMP  header  followed  by  an
           arbitrary  amount  of data.  When a packetsize is given, this indicated
           the size of this extra piece of data (the  default  is  56).  Thus  the
           amount  of data received inside of an IP packet of type ICMP ECHO_REPLY
           will always be 8 bytes more than the requested  data  space  (the  ICMP
           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 (inter)network layer should never treat packets differently depend-
           ing  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 pat-
           tern 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 trans-
           mit 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 man-
           age 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 decre-
           ment 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  tel-
           net(1) or ftp(1).
           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
           ? 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
           ? 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.


           The ping command appeared in 4.3BSD.
           The version described here is its descendant specific to Linux.


           ping  requires  CAP_NET_RAWIO capability to be executed. It may be used
           as set-uid root.


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

    iputils-071127 23 July 2015 PING(8)


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