NAME

lo - software loopback network interface

SYNOPSIS

d = open ("/dev/loop", O_RDWR);

DESCRIPTION

The loopback device is a software datalink provider (interface driver) that returns all packets it receives to their source without involving any hardware devices. It is a STREAMS device conforming to the datalink provider interface (DLPI). See if(7) for a general description of network interfaces.

The loopback interface is used to access Internet services on the local machine. Because it is available on all machines, including those with no hardware network interfaces, programs can use it for guaranteed access to local servers. A typical application is the comsat(1M) server which accepts notification of mail delivery from a local client. The loopback interface is also used for performance analysis and testing.

By convention, the name of the loopback  interface  is  lo0,
and  it is configured with Internet address 127.0.0.1.  This
address may be changed with the SIOCSIFADDR ioctl().

SEE ALSO

comsat(1M), if(7), inet(7).