Table of Contents ICMP
for IP Version 6
Ping is the simplest of all TCP/IP applications. It sends one or more IP datagrams to a specified destination host requesting a reply and measures the round trip time. The word ping, which is used as a noun and a verb, is taken from the sonar operation to locate an underwater object. It is also an abbreviation for Packet InterNet Groper.
Traditionally, if you could ping a host other applications like Telnet or FTP could reach that host. With the advent of security measures on the Internet, particularly firewalls (see Firewalls), which control access to networks by application protocol and/or port number, this is no longer strictly true. Nonetheless, the first test of reachability for a host is still to attempt to ping it.
The syntax that is used in different implementations of ping varies from platform to platform. The syntax here is for the OS/2 implementation:
ping [-switches] host [size [packets]]Where:
Ping uses the ICMP Echo and Echo Reply messages, as described in Echo (8) and Echo Reply (0). Since ICMP is required in every TCP/IP implementation, hosts do not require a separate server to respond to pings.
Ping is useful for verifying a TCP/IP installation. Consider the following four forms of the command; each requires the operation of an additional part of the TCP/IP installation.
Ping is implemented in all IBM TCP/IP products. TCP/IP for OS/2 (including the OS/2 Warp LAN Client version) also has a Presentation Manager program called PM Ping that uses ping to monitor a user-defined list of hosts stored in the file \TCPIP\ETC\PINGHOST.LST. This program can be iconized: when all hosts are responding, the icon is green, but if one or more hosts do not respond, the icon turns red.
Table of Contents Traceroute