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handbook:handbook:networking4

Testing networking

Testing the networking interfaces is usually done by some system utilities which are actually using the specific interface. For example, to test if the local loopback interface is on, you can simply ping the lo IP address:

$ping 127.0.0.1
64 bytes from 127.0.0.1: icmp_seq=0 ttl=255 time=0.4 ms
64 bytes from 127.0.0.1: icmp_seq=1 ttl=255 time=0.4 ms
64 bytes from 127.0.0.1: icmp_seq=2 ttl=255 time=0.4 ms
.......

As we can see, we get a reply from 127.0.0.1, which indicates that the lo interface is up and running.

Using the ping utility a lot of other interfaces could be checked. For example Ethernet interfaces, assuming that there is another host in our network, named host1:

$ping host1
64 bytes from 175.26.1.1: icmp_seq=0. time=11. ms
64 bytes from 175.26.1.1: icmp_seq=1. time=7. ms
64 bytes from 175.26.1.1: icmp_seq=2. time=12. ms
64 bytes from 175.26.1.1: icmp_seq=3. time=3. ms
 ......

Since we can get reply from host1, we know that we can successfully communicate with that host, and any other host in our network.

To test your Internet connection, you can simply try to ping some well-known server, such as www.yahoo.com , or www.google.com:

$ping www.yahoo.com
64 bytes from 216.109.118.76: icmp_seq=0. time=13. ms
64 bytes from 216.109.118.76: icmp_seq=1. time=8. ms
64 bytes from 216.109.118.76: icmp_seq=2. time=14. ms
64 bytes from 216.109.118.76: icmp_seq=3. time=7. ms
.......

Almost every network interface can be tested by pinging the devices it is designed to communicate with. If the reply is positive, then the interface can do its job, if not, then you must reconfigure it.

handbook/handbook/networking4.txt · Last modified: 2010/04/15 21:18 (external edit)