lo - software loopback network interface
Synopsis Description Diagnostics See Also History Bugs
.Cd "device loop"
The loop interface is a software loopback mechanism which may be used for performance analysis, software testing, and/or local communication. As with other network interfaces, the loopback interface must have network addresses assigned for each address family with which it is to be used. These addresses may be set or changed with the SIOCSIFADDR ioctl(2). The loopback interface should be the last interface configured, as protocols may use the order of configuration as an indication of priority. The loopback should never be configured first unless no hardware interfaces exist.