LO(4N)

NAME
lo - software loopback network interface

SYNOPSIS
pseudo-device loop

DESCRIPTION

The loop device is a software loopback network interface; see if(4N) for a general description of network interfaces.

The loop interface is used for performance analysis and software testing, and to provide guaranteed access to Internet protocols on machines with no local network interfaces. A typical application is the comsat(8C) server which accepts notification of mail delivery through a particular port on the loopback interface.

By default, the loopback interface is accessible at Internet address 127.0.0.1 (non-standard); this address may be changed with the SIOCSIFADDR ioctl.

SEE ALSO
if(4N), inet(4F), comsat(8C)

DIAGNOSTICS

lo%d: can't handle af%d
    The interface was handed a message with addresses formatted in an unsuitable address family; the packet was dropped.

BUGS
It should handle all address and protocol families. An approved network address should be reserved for this interface.