| LO(4) |
AerieBSD 1.0 Refernce Manual |
LO(4) |
NAME
lo —
software loopback network interface
SYNOPSIS
.Cd "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.
A
loop
interface can be created at runtime using the
ifconfiglo
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.
Configuring a loopback interface for
inet(4)
with the
link1
flag set will make the interface answer to the whole set of
addresses identified as being in super-net which is specified
by the address and netmask.
Obviously you should not set the
link1
flag on interface
lo0,
but instead use another interface like
lo1.
EXAMPLES
# ifconfig lo1 create
# ifconfig lo1 inet 192.168.1.1 netmask 255.255.255.0 link1
is equivalent to:
# ifconfig lo1 create
# awk 'BEGIN {for(i=1;i<255;i++) \e
print "ifconfig lo1 inet 192.168.1."i" netmask 255.255.255.255 alias"}'| \e
sh
DIAGNOSTICS
The interface was handed
a message with addresses formatted in an unsuitable address
family; the packet was dropped.
SEE ALSO
inet(4),
inet6(4),
netintro(4),
hostname.if(5),
ifconfig(8),
netstart(8)
HISTORY
The
lo
device appeared in
4.2BSD.
The wildcard functionality first appeared in
OpenBSD 2.3.
BUGS
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.
Care should be taken when using NAT with interfaces that have the
link1
flag set, because it may believe the packets are coming from a
loopback address.
| AerieBSD 1.0 Reference Manual |
August 26 2008 |
LO(4) |