document the link1 flag

1 files changed, 21 insertions, 3 deletions

diff --git a/share/man/man4/lo.4 b/share/man/man4/lo.4
index 0491936b493..c53e9cc7e27 100644
--- a/share/man/man4/lo.4
+++ b/share/man/man4/lo.4
@@ -1,3 +1,4 @@
+.\"	$OpenBSD: lo.4,v 1.2 1998/02/01 18:31:57 mickey Exp $
 .\"	$NetBSD: lo.4,v 1.3 1994/11/30 16:22:23 jtc Exp $
 .\"
 .\" Copyright (c) 1983, 1991, 1993
@@ -40,8 +41,7 @@
 .Nm lo
 .Nd software loopback network interface
 .Sh SYNOPSIS
-.Sy pseudo-device
-.Nm loop
+.Sy pseudo-device Nm loop Em <number>
 .Sh DESCRIPTION
 The
 .Nm loop
@@ -60,6 +60,14 @@ The loopback should
 .Em never
 be configured first unless no hardware
 interfaces exist.
+.Pp
+Configuring loopback interface for
+.Xr inet 4
+with
+.Em link1
+flag set you achieve a functionality such as equivalent to setting
+the whole set of addresses wich belongs to the sub/super-net of the
+address and netmask configured on the interface.
 .Sh DIAGNOSTICS
 .Bl -diag
 .It lo%d: can't handle af%d.
@@ -67,15 +75,25 @@ The interface was handed
 a message with addresses formatted in an unsuitable address
 family; the packet was dropped.
 .El
+.Sh EXAMPLES
+ifconfig lo1 inet 192.168.1.1 netmask 255.255.255.0 link1
+this would configure lo1 the way equivalent to:
+.Pp
+awk 'BEGIN {for(i=1;i<255;i++) \
+print "ifconfig lo1 inet 192.168.1."i" netmask 255.255.255.255"}'|sh
 .Sh SEE ALSO
 .Xr intro 4 ,
 .Xr inet 4 ,
-.Xr ns 4
+.Xr ns 4 ,
+.Xr ifconfig 8
 .Sh HISTORY
 The
 .Nm
 device appeared in
 .Bx 4.2 .
+.Pp
+The wildcard functionality first appeared in
+.Ox 2.2 .
 .Sh BUGS
 Previous versions of the system enabled the loopback interface
 automatically, using a nonstandard Internet address (127.1).