lo(7)lo(7)NAMElo - Software loopback network interface
SYNOPSIS
pseudo-device loop
DESCRIPTION
The loopback interface is a software loopback mechanism which is used
for performance analysis, software testing, and/or local communication.
As with other network interfaces, the loopback interface must have net‐
work addresses assigned for each address family with which it is to be
used. These addresses may be set or changed with the SIOCSIFADDR ioctl.
The loopback interface should be the last interface configured, as pro‐
tocols may use the order of configuration as an indication of priority.
The loopback should never be configured first unless no hardware inter‐
faces exist.
NOTES
Previous versions of the UNIX 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.
ERRORS
The interface was handed a message with addresses formatted in an
unsuitable address family; the packet was dropped.
SEE ALSO
Networking: inet(7), netintro(7)lo(7)