Pingi Larte – Kick

Pingi Larte – Kick

Pingi Larte – Kick





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ping is a computer network administration software utility used to test the reachability of a host on an Internet Protocol (IP) network. It 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] although it is sometimes interpreted as a backronym to packet Internet groper.[2]

Ping operates by sending Internet Control Message Protocol (ICMP) echo request packets 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, and interval between the requests. Many systems provide a companion utility ping6, for testing on Internet Protocol version 6 (IPv6) networks, which implement ICMP6.
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.
Generic composition of an ICMP packet:[8]

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), calculated with the ICMP part of the packet (the IP header is not used). It is the 16-bit one’s complement of the one’s complement sum of the ICMP message starting with the Type field[9]
Header Data (32 bits) field, which in this case (ICMP echo request and replies), will be composed of 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.
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 completely wake up all devices, 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 considerations[edit]
The “flood” ping option exists in many implementations, sending requests as fast as possible in an attempt to determine the response of the network under high-load conditions. That option is restricted to users having administrative privileges, but may be used in denial-of-service attacks to induce a ping flood, in which the attacker attempts to overwhelm the victim with ICMP e

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