NAME
lo
- software loopback network interface
SYNOPSIS
pseudo-device loop
DESCRIPTION
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.
The loopback interface
lo0
is created at boottime, it always exists and cannot be destroyed
with
ifconfig(8).
Additional loopback interfaces can be created by using the
ifconfig(8)
create
command.
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.
SEE ALSO
inet(4),
intro(4),
ifconfig(8)
HISTORY
The
lo
device appeared in
4.2BSD.
BUGS
Previous versions of the system enabled the loopback interface
automatically, using a nonstandard Internet address (127.1).
Use of that address is now discouraged; a reserved host address
for the local network should be used instead.