ICMP echo packets for IP network diagnosis and measurements. ICMP echo requests and all ping commands pdf echo replies in return. However, as a security consideration, this is often disabled. 5 packets transmitted, 5 packets received, 0.
The output lists each probe message and the results obtained. Finally it lists the statistics of the entire test. 674 ms, the average was 10. 968 ms, and the maximum value was 11. In cases of no response from the target host, most implementations display either nothing or periodically print notifications about timing out.
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”. 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. The payload may include a timestamp indicating the time of transmission and a sequence number, which are not found in this example. 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.