lo —
software loopback network interface
pseudo-device loop
The
loop interface is a software loopback
mechanism which may be used for performance analysis, software testing, and/or
local communication.
A
loop interface can be created at runtime
using the
ifconfig
loN
create command or by setting up a
hostname.if(5)
configuration file for
netstart(8). The
lo0 interface will always exist and cannot
be destroyed using
ifconfig(8).
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.
- lo0: can't handle afX.
- The interface was handed a message with addresses formatted in an
unsuitable address family; the packet was dropped.
inet(4),
inet6(4),
netintro(4),
hostname.if(5),
ifconfig(8),
netstart(8)
The
lo device appeared in
4.2BSD.
Previous versions of the system enabled the loopback interface automatically,
using a non-standard Internet address (127.1). Use of that address is now
discouraged; a reserved host address for the local network should be used
instead.
![[OpenBSD]](/openbsd.gif){kind=small}