Localhost

In the field of the Data-processing networks, localhost (the local host in English) is a name used to refer to the local Ordinateur.

One makes use of it to communicate with our machine via the protocol IP. The name localhost is associated with the Adresse IPv4 127.0.0.1 and with the Adresse IPv6 :: 1 (subject to the availability of one or the other of the versions of protocol IP).

The virtual interface Ethernet used in this situation names the interface of loopback (shortened by lo if you type the order ifconfig under Unix)

In practice

If I am in front of a machine having a functional pile TCP/IP I can use localhost , even if this one is connected to no physical network. For example, to know if the pile TCP/IP functions my machine of course, I can use the order Ping on localhost .

That gives for example with IPv4:

$ ping localhost PING localhost (127.0.0.1): 56 dated bytes 64 bytes from 127.0.0.1: icmp_seq=0 ttl=64 time=0.3 ms 64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.1 ms 64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.1 ms 64 bytes from 127.0.0.1: icmp_seq=3 ttl=64 time=0.1 ms …

Is still with IPv6:

$ ping6 localhost PING localhost (:: 1) from:: 1: 56 dated bytes 64 bytes from:: 1: icmp_seq=1 ttl=64 time=0.057 ms 64 bytes from:: 1: icmp_seq=2 ttl=64 time=0.052 ms 64 bytes from:: 1: icmp_seq=3 ttl=64 time=0.049 ms …

Internal bonds

Address IP
Resolution of names
Orders Unix

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