Operation Manual
23.6.2.2 Testing a Connection with ping
The ping command is the standard tool for testing whether a TCP/IP connection works.
It uses the ICMP protocol to send a small data packet, ECHO_REQUEST datagram,
to the destination host, requesting an immediate reply. If this works, ping displays a
message to that effect, which indicates that the network link is basically functioning.
ping does more than only test the function of the connection between two computers:
it also provides some basic information about the quality of the connection. In Exam-
ple 23.10, “Output of the Command ping” (page 410), you can see an example of the
ping output. The second-to-last line contains information about the number of trans-
mitted packets, packet loss, and total time of ping running.
As the destination, you can use a hostname or IP address, for example,
ping example.com or ping 192.168.3.100. The program sends packets until
you press Ctrl + C.
If you only need to check the functionality of the connection, you can limit the number
of the packets with the -c option. For example to limit ping to three packets, enter
ping -c 3 example.com.
Example 23.10
Output of the Command ping
ping -c 3 example.com
PING example.com (192.168.3.100) 56(84) bytes of data.
64 bytes from example.com (192.168.3.100): icmp_seq=1 ttl=49 time=188 ms
64 bytes from example.com (192.168.3.100): icmp_seq=2 ttl=49 time=184 ms
64 bytes from example.com (192.168.3.100): icmp_seq=3 ttl=49 time=183 ms
--- example.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2007ms
rtt min/avg/max/mdev = 183.417/185.447/188.259/2.052 ms
The default interval between two packets is one second. To change the interval, ping
provides the option -i. For example, to increase the ping interval to ten seconds, enter
ping -i 10 example.com.
In a system with multiple network devices, it is sometimes useful to send the ping
through a specic interface address. To do so, use the -I option with the name of the
selected device, for example, ping -I wlan1 example.com.
For more options and information about using ping, enter ping -h or see the ping
(8) man page.
410 Reference