What is Ping? Not the Ping golf club, but the Pinging that is used on the internet?
Ping– name of the program used in computer networks TCP / IP (such as the Internet ) is used to diagnose network connectivity. It allows you to check whether there is a connection between the hosts and tested testing. It allows to measure the number of lost packets and delays in their transmission, called the lag .
Mike Muuss (1958-2000) invented and wrote the first implementation of the ping in December 1983 under 4.2aBSD Unix . Together with the necessary changes in the kernel it appears in the 4.xBSD Unix.
The author has used the English onomatopoeia word ping signals similar to the active sonar , which sends out signals in the direction of another ship will allow it to be identified on the basis of an echo. Ping program operates in a similar way. In both cases, a signal is sent, which eventually bounced back.
Over time the program was treated as an acronym for which found many expansions. One of the most popular, in English, is Packet Internet Groper (Groper is one who looks in the dark / in the dark).
By analogy to the sonar technology, the author also used the name of the ping packets used by the program.
Sometimes the answer to the ping (ICMP Echo Reply) is also called pong.
Action of Pinging
Ping uses the protocol ICMP , it sends an ICMP echo request and receives ICMP Echo Reply.
Most of the publicly available servers support these packages. In this case, the ping application allows you to check proper operation of the network, but most users of the program ping is erroneously believe that if the remote host does not respond to pings sent, it is so only when it is turned on or is the problem with the network between the two machines.
It should therefore remember that the packet-blocking ICMP Echo Reply response (used for this purpose firewalls or filters in the routers ) is one of the common methods of protection against attacks from the network. This is because the analysis of ICMP Echo Reply is not only confirms the existence of a host IP address, but often also allows accurate determination of the operating system, making it easier to attack your computer.
Also, the answer to the ping does not mean that the service (eg website www ) on this system works, or even the operating system still works.
Ping in action
Implementations of the AIX and iputils package (for systems of Unix , Linux and Cygwin ) send the packets all the time, the versions of Solaris by default or only provide a response was received, the implementations of the Microsoft Windows send the four packages.