-.TH LO 4 "26 March 1982"
-.UC 4
+.\" Copyright (c) 1983 Regents of the University of California.
+.\" All rights reserved. The Berkeley software License Agreement
+.\" specifies the terms and conditions for redistribution.
+.\"
+.\" @(#)lo.4 6.3 (Berkeley) 5/21/86
+.\"
+.TH LO 4 "May 21, 1986"
+.UC 5
.SH NAME
lo \- software loopback network interface
.SH SYNOPSIS
.I loop
interface is a software loopback mechanism which may be
used for performance analysis, software testing, and/or local
-communication. By default, the loopback interface is
-accessible at address 127.0.0.1 (non-standard); this address
-may be changed with the SIOCSIFADDR ioctl.
+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.
+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 \fBnever\fP be configured first unless no hardware
+interfaces exist.
.SH DIAGNOSTICS
\fBlo%d: can't handle af%d\fP. The interface was handed
a message with addresses formatted in an unsuitable address
family; the packet was dropped.
.SH SEE ALSO
-intro(4N), inet(4F)
+intro(4N), inet(4F), ns(4F)
.SH BUGS
-It should handle all address and protocol families.
-An approved network address should be reserved for this
-interface.
+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.