Коды ошибок команды ping

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Linux version of ping
Original author(s)	Mike Muuss
Developer(s)	Various open-source and commercial developers
Initial release	1983; 40 years ago
Platform	Cross-platform
Type	Command
License	Public-domain, BSD, GPL, MIT

ping is a computer network administration software utility used to test the reachability of a host on an Internet Protocol (IP) network. It is available for virtually all operating systems that have networking capability, including most embedded network administration software.

Ping measures the round-trip time for messages sent from the originating host to a destination computer that are echoed back to the source. The name comes from active sonar terminology that sends a pulse of sound and listens for the echo to detect objects under water.^[1]

Ping operates by means of Internet Control Message Protocol (ICMP) packets. Pinging involves sending an ICMP echo request to the target host and waiting for an ICMP echo reply. The program reports errors, packet loss, and a statistical summary of the results, typically including the minimum, maximum, the mean round-trip times, and standard deviation of the mean.

The command-line options of the ping utility and its output vary between the numerous implementations. Options may include the size of the payload, count of tests, limits for the number of network hops (TTL) that probes traverse, interval between the requests and time to wait for a response. Many systems provide a companion utility ping6, for testing on Internet Protocol version 6 (IPv6) networks, which implement ICMPv6.

History[edit]

The ping utility was written by Mike Muuss in December 1983 during his employment at the Ballistic Research Laboratory, now the US Army Research Laboratory. A remark by David Mills on using ICMP echo packets for IP network diagnosis and measurements prompted Muuss to create the utility to troubleshoot network problems.^[1] The author named it after the sound that sonar makes, since its methodology is analogous to sonar’s echolocation.^[1][2] The backronym Packet InterNet Groper for PING has been used for over 30 years,^[timeframe?] and although Muuss says that from his point of view PING was not intended as an acronym, he has acknowledged Mills’ expansion of the name.^[1][3] The first released version was public domain software; all subsequent versions have been licensed under the BSD license. Ping was first included in 4.3BSD.^[4] The FreeDOS version was developed by Erick Engelke and is licensed under the GPL.^[5] Tim Crawford developed the ReactOS version. It is licensed under the MIT License.^[6]

RFC 1122 prescribes that any host must process ICMP echo requests and issue echo replies in return.^[7]

Invocation example[edit]

The following is the output of running ping on Linux for sending five probes (1-second interval by default, configurable via -i option) to the target host www.example.com:

$ ping -c 5 www.example.com

PING www.example.com (93.184.216.34): 56 data bytes
64 bytes from 93.184.216.34: icmp_seq=0 ttl=56 time=11.632 ms
64 bytes from 93.184.216.34: icmp_seq=1 ttl=56 time=11.726 ms
64 bytes from 93.184.216.34: icmp_seq=2 ttl=56 time=10.683 ms
64 bytes from 93.184.216.34: icmp_seq=3 ttl=56 time=9.674 ms
64 bytes from 93.184.216.34: icmp_seq=4 ttl=56 time=11.127 ms

--- www.example.com ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 9.674/10.968/11.726/0.748 ms

The output lists each probe message and the results obtained. Finally, it lists the statistics of the entire test. In this example, the shortest round trip time was 9.674 ms, the average was 10.968 ms, and the maximum value was 11.726 ms. The measurement had a standard deviation of 0.748 ms.

Error indications[edit]

In cases of no response from the target host, most implementations display either nothing or periodically print notifications about timing out. Possible ping results indicating a problem include the following:

• H, !N or !P – host, network or protocol unreachable
• S – source route failed
• F – fragmentation needed
• U or !W – destination network/host unknown
• I – source host is isolated
• A – communication with destination network administratively prohibited
• Z – communication with destination host administratively prohibited
• Q – for this ToS the destination network is unreachable
• T – for this ToS the destination host is unreachable
• X – communication administratively prohibited
• V – host precedence violation
• C – precedence cutoff in effect

In case of error, the target host or an intermediate router sends back an ICMP error message, for example host unreachable or TTL exceeded in transit. In addition, these messages include the first eight bytes of the original message (in this case header of the ICMP echo request, including the quench value), so the ping utility can match responses to originating queries.^[8]

Message format[edit]

ICMP packet[edit]

Generic composition of an ICMP packet:^[9]

• IPv4 Header (in blue): protocol set to 1 (ICMP) and Type of Service set to 0.
• IPv6 Header (in blue): Next Header set to 58 (ICMP6)
• ICMP Header (in red):
  • Type of ICMP message (8 bits)
  • Code (8 bits)
  • Checksum (16 bits), the 16-bit one’s complement of the one’s complement sum of the packet. For IPv4, this is calculated from the ICMP message starting with the Type field^[10] (the IP header is not included). For IPv6 this is calculated from the ICMP message, prepended with an IPv6 pseudo-header.^[11]
  • Header Data (32 bits) field, which in this case (ICMP echo request and replies), will be composed of an identifier (16 bits) and sequence number (16 bits).
• ICMP Payload: payload for the different kind of answers; can be an arbitrary length, left to implementation detail. However, the packet including IP and ICMP headers must be less than the maximum transmission unit of the network or risk being fragmented.

Echo request[edit]

The echo request (ping) is an ICMP/ICMP6 message.

The Identifier and Sequence Number can be used by the client to match the reply with the request that caused the reply. In practice, most Linux systems use a unique identifier for every ping process, and sequence number is an increasing number within that process. Windows uses a fixed identifier, which varies between Windows versions, and a sequence number that is only reset at boot time.

Echo reply[edit]

The echo reply is an ICMP message generated in response to an echo request; it is mandatory for all hosts and must include the exact payload received in the request.

• The identifier and sequence number can be used by the client to associate each echo request with its reply.

Payload[edit]

The payload of the packet is generally filled with ASCII characters, as the output of the tcpdump utility shows in the last 32 bytes of the following example (after the eight-byte ICMP header starting with 0x0800):

16:24:47.966461 IP (tos 0x0, ttl 128, id 15103, offset 0, flags [none],
proto: ICMP (1), length: 60) 192.168.146.22 > 192.168.144.5: ICMP echo request,
id 1, seq 38, length 40
       0x0000:  4500 003c 3aff 0000 8001 5c55 c0a8 9216  E..<:.....\U....
       0x0010:  c0a8 9005 0800 4d35 0001 0026 6162 6364  ......M5...&abcd
       0x0020:  6566 6768 696a 6b6c 6d6e 6f70 7172 7374  efghijklmnopqrst
       0x0030:  7576 7761 6263 6465 6667 6869            uvwabcdefghi

The payload may include a timestamp indicating the time of transmission and a sequence number, which are not found in this example. This allows ping to compute the round trip time in a stateless manner without needing to record the time of transmission of each packet.

The payload may also include a magic packet for the Wake-on-LAN protocol, but the minimum payload, in that case, is longer than shown. The Echo Request typically does not receive any reply if the host was sleeping in hibernation state, but the host still wakes up from sleep state if its interface is configured to accept wakeup requests. If the host is already active and configured to allow replies to incoming ICMP Echo Request packets, the returned reply should include the same payload. This may be used to detect that the remote host was effectively woken up, by repeating a new request after some delay to allow the host to resume its network services. If the host was just sleeping in low power active state, a single request wakes up that host just enough to allow its Echo Reply service to reply instantly if that service was enabled. The host does not need to wake up all devices completely and may return to low-power mode after a short delay. Such configuration may be used to avoid a host to enter in hibernation state, with much longer wake-up delay, after some time passed in low power active mode.^{[citation needed]}

Security loopholes[edit]

To conduct a denial-of-service attack, an attacker may send ping requests as fast as possible, possibly overwhelming the victim with ICMP echo requests. This technique is called a ping flood.^[12]

Ping requests to multiple addresses, ping sweeps, may be used to obtain a list of all hosts on a network.

See also[edit]

References[edit]

Further reading[edit]

• Dyson, Peter (1995). Mastering OS/2 Warp. Sybex. ISBN 978-0782116632.
• John Paul Mueller (2007). Windows Administration at the Command Line for Windows Vista, Windows 2003, Windows XP, and Windows 2000. John Wiley & Sons. ISBN 978-0470165799.
• McElhearn, Kirk (2006). The Mac OS X Command Line: Unix Under the Hood. John Wiley & Sons. ISBN 978-0470113851.

External links[edit]

• ping(1M) – Solaris 11.4 Reference Manual
• ping(8) – FreeBSD System Manager’s Manual
• ping(8) – Linux Programmer’s Manual – Administration and Privileged Commands
• ping | Microsoft Docs

PING (Packet Internet Groper) is a program used to test whether a particular network host is online by sending an ICMP (Internet control message protocol) echo request and waiting for a response. It is used for troubleshooting connectivity between network devices such as servers, routers, workstations and printers. It is one of the most commonly used tools used to troubleshoot network connectivity between devices.

You can ping a host from a command prompt simply by typing ping followed by the IP address. For example type ping 192.168.0.1 to see if the host with the 192.168.0.1 IP address is reachable. It also works with hostnames on the same network so if you have a server called WebServer you can type in ping WebServer to check for connectivity. You can also ping a website by typing ping www.microsoft.com to check its availability. For Windows computers you will need to allow ICMP packets through the firewall in order to be able to ping those computers.

To use the PING utility simply open a command prompt from your Start menu or type in cmd from your run command box or your search box.

When a PING is successful you get a reply back from the host showing its IP address and other information such as the time it took for the reply to go through.

When a ping response is not successful you can get a variety of error replies. Here are the main error messages and what they mean.

TTL Expired in Transit
The TTL value determines the maximum amount of time an IP packet may live in the network without reaching its destination. It is effectively a bound on the number of routers an IP packet may pass through before being discarded. This message indicates that the TTL expired in transit. Number of required hops exceeds TTL. Increase TTL by using the ping -i switch.

Destination Host Unreachable
The host that you are trying to ping is down or is not operating on the network. A local or remote route does not exist for destination host. Modify the local route table or notify the router administrator.

Request Timed Out
The ping command timed out because there was no reply from the host. No Echo Reply messages were received due to network traffic, failure of the ARP request packet filtering, or router error. Increase the wait time using the ping -w switch.

Unknown Host
The IP Address or the Host Name does not exist in the network or the destination host name cannot be resolved. Verify name and availability of DNS servers.

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

NAME

     ping -- send ICMP ECHO_REQUEST packets to network hosts

SYNOPSIS

     ping [-AaCDdfnoQqRrv] [-b boundif] [-c count] [-G sweepmaxsize]
          [-g sweepminsize] [-h sweepincrsize] [-i wait] [-l preload]
          [-M mask | time] [-m ttl] [-P policy] [-p pattern] [-S src_addr]
          [-s packetsize] [-t timeout] [-W waittime] [-z tos] host
     ping [-AaDdfLnoQqRrv] [-b boundif] [-c count] [-I iface] [-i wait]
          [-l preload] [-M mask | time] [-m ttl] [-P policy] [-p pattern]
          [-S src_addr] [-s packetsize] [-T ttl] [-t timeout] [-W waittime]
          [-z tos] mcast-group

DESCRIPTION

     The ping utility 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.  The options are as follows:

     -A      Audible.  Output a bell (ASCII 0x07) character when no packet is
             received before the next packet is transmitted.  To cater for
             round-trip times that are longer than the interval between trans-
             missions, further missing packets cause a bell only if the maxi-
             mum number of unreceived packets has increased.

     -a      Audible.  Include a bell (ASCII 0x07) character in the output
             when any packet is received.  This option is ignored if other
             format options are present.

     -b boundif
             Bind the socket to interface boundif for sending.

     -C      Prohibit the socket from using the cellular network interface.

     -c count
             Stop after sending (and receiving) count ECHO_RESPONSE packets.
             If this option is not specified, ping will operate until inter-
             rupted.  If this option is specified in conjunction with ping
             sweeps, each sweep will consist of count packets.

     -D      Set the Don't Fragment bit.

     -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 sweepmaxsize
             Specify the maximum size of ICMP payload when sending sweeping
             pings.  This option is required for ping sweeps.

     -g sweepminsize
             Specify the size of ICMP payload to start with when sending
             sweeping pings.  The default value is 0.

     -h sweepincrsize
             Specify the number of bytes to increment the size of ICMP payload
             after each sweep when sending sweeping pings.  The default value
             is 1.

     -I iface
             Source multicast packets with the given interface address.  This
             flag only applies if the ping destination is a multicast address.

     -i wait
             Wait wait seconds between sending each packet.  The default is to
             wait for one second between each packet.  The wait time may be
             fractional, but only the super-user may specify values less than
             0.1 second.  This option is incompatible with the -f option.

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

     -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.

     -M mask | time
             Use ICMP_MASKREQ or ICMP_TSTAMP instead of ICMP_ECHO.  For mask,
             print the netmask of the remote machine.  Set the
             net.inet.icmp.maskrepl MIB variable to enable ICMP_MASKREPLY.
             For time, print the origination, reception and transmission time-
             stamps.

     -m ttl  Set the IP Time To Live for outgoing packets.  If not specified,
             the kernel uses the value of the net.inet.ip.ttl MIB variable.

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

     -o      Exit successfully after receiving one reply packet.

     -P policy
             policy specifies IPsec policy for the ping session.  For details
             please refer to ipsec(4) and ipsec_set_policy(3).

     -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      Somewhat quiet output.  Don't display ICMP error messages that
             are in response to our query messages.  Originally, the -v flag
             was required to display such errors, but -v displays all ICMP
             error messages.  On a busy machine, this output can be overbear-
             ing.  Without the -Q flag, ping prints out any ICMP error mes-
             sages caused by its own ECHO_REQUEST messages.

     -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; the traceroute(8) command is usually better at
             determining the route packets take to a particular destination.
             If more routes come back than should, such as due to an illegal
             spoofed packet, ping will print the route list and then truncate
             it at the correct spot.  Many hosts ignore or discard the
             RECORD_ROUTE option.

     -r      Bypass the normal routing tables and send directly to a host on
             an attached network.  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
             (e.g., after the interface was dropped by routed(8)).

     -S src_addr
             Use the following IP address as the source address in outgoing
             packets.  On hosts with more than one IP address, this option can
             be used to force the source address to be something other than
             the IP address of the interface the probe packet is sent on.  If
             the IP address is not one of this machine's interface addresses,
             an error is returned and nothing is sent.

     -s packetsize
             Specify 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.  This option cannot be used with ping
             sweeps.

     -T ttl  Set the IP Time To Live for multicasted packets.  This flag only
             applies if the ping destination is a multicast address.

     -t timeout
             Specify a timeout, in seconds, before ping exits regardless of
             how many packets have been received.

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

     -W waittime
             Time in milliseconds to wait for a reply for each packet sent.
             If a reply arrives later, the packet is not printed as replied,
             but considered as replied when calculating statistics.

     -z tos  Use the specified type of service.

     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 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, mean, maximum, and standard deviation of
     the round-trip times.

     If ping receives a SIGINFO (see the status argument for stty(1)) signal,
     the current number of packets sent and received, and the minimum, mean,
     and maximum of the round-trip times will be written to the standard error
     output.

     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 ping during normal operations or from automated scripts.

ICMP PACKET DETAILS

     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 arbi-
     trary 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 header).

     If the data space is at least eight bytes large, ping uses the first
     eight bytes of this space to include a timestamp which it uses in the
     computation of round trip times.  If less than eight bytes of pad are
     specified, no round trip times are given.

DUPLICATE AND DAMAGED PACKETS

     The ping utility 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
     presence 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 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 ping.

TTL DETAILS

     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 recommends setting the TTL field for IP packets
     to 64, but many systems use smaller values (4.3BSD uses 30, 4.2BSD 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 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:

     o   Not change it; this is what BSD 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.

     o   Set it to 255; this is what current BSD 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.

     o   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.

EXIT STATUS

     The ping utility exits with one of the following values:

     0       At least one response was heard from the specified host.

     2       The transmission was successful but no responses were received.

     any other value
             An error occurred.  These values are defined in <sysexits.h>.

SEE ALSO

     netstat(1), ifconfig(8), routed(8), traceroute(8), ping6(8)

HISTORY

     The ping utility appeared in 4.3BSD.

AUTHORS

     The original ping utility was written by Mike Muuss while at the US Army
     Ballistics Research Laboratory.

BUGS

     Many Hosts and Gateways ignore the RECORD_ROUTE option.

     The maximum IP header length is too small for options like RECORD_ROUTE
     to be completely useful.  There's not much that can be done about this,
     however.

     Flood pinging is not recommended in general, and flood pinging the broad-
     cast address should only be done under very controlled conditions.

     The -v option is not worth much on busy hosts.

BSD                             March 29, 2013                             BSD

Mac OS X 10.9 — Generated Fri Oct 18 06:31:53 CDT 2013