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### 2. The Ping tab

### 2.1 What is it?

The `ping(8)` command sends ICMP `ECHO_REQUEST` packets to network hosts to check for network reachability. A response from a host (or anything that have an IP address) says that this host is running at least a TCP/IP network stack and indicates that the network route to go to this host is opened. The ping tab allows the execution of the `ping(8)` command.

### 2.2 Description

Ping 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.

### 2.3 Options

Make host name resolution

  Print addresses numerically rather than symbolically and numerically (this saves a nameserver address-to-name lookup).

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 calculation, although the round trip time of these packets is used in calculating the minimum/average/maximum round-trip time numbers. When the program is terminated, a brief summary is displayed.

This program is intended for use in network testing, measurement and management. Because of the load it can impose on the network, it is unwise to use ping during normal operations or for too long.

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