Improve flexibility of receiving Router Advertisement and

automatic link-local address configuration:

- Convert a sysctl net.inet6.ip6.accept_rtadv to one for the
  default value of a per-IF flag ND6_IFF_ACCEPT_RTADV, not a
  global knob.  The default value of the sysctl is 0.

- Add a new per-IF flag ND6_IFF_AUTO_LINKLOCAL and convert a
  sysctl net.inet6.ip6.auto_linklocal to one for its default
  value.  The default value of the sysctl is 1.

- Make ND6_IFF_IFDISABLED more robust.  It can be used to disable
  IPv6 functionality of an interface now.

- Receiving RA is allowed if ip6_forwarding==0 *and*
  ND6_IFF_ACCEPT_RTADV is set on that interface.  The former
  condition will be revisited later to support a "host + router" box
  like IPv6 CPE router.  The current behavior is compatible with
  the older releases of FreeBSD.

- The ifconfig(8) now supports these ND6 flags as well as "nud",
  "prefer_source", and "disabled" in ndp(8).  The ndp(8) now
  supports "auto_linklocal".

Discussed with:	bz and jinmei
Reviewed by:	bz
MFC after:	3 days

1 files changed, 55 insertions, 9 deletions

diff --git a/sbin/ifconfig/ifconfig.8 b/sbin/ifconfig/ifconfig.8
index 1d2f096..f4bcc5a 100644
--- a/sbin/ifconfig/ifconfig.8
+++ b/sbin/ifconfig/ifconfig.8
@@ -28,7 +28,7 @@
 .\"     From: @(#)ifconfig.8	8.3 (Berkeley) 1/5/94
 .\" $FreeBSD$
 .\"
-.Dd July 8, 2009
+.Dd September 2, 2009
 .Dt IFCONFIG 8
 .Os
 .Sh NAME
@@ -598,6 +598,48 @@ If the interface was reset when previously marked down,
 the hardware will be re-initialized.
 .El
 .Pp
+The following parameters are for ICMPv6 Neightbor Discovery Protocol:
+.Bl -tag -width indent
+.It Cm accept_rtadv
+Set a flag to enable accepting ICMPv6 Router Advertisement messages.
+.It Cm -accept_rtadv
+Clear a flag
+.Cm accept_rtadv .
+.It Cm auto_linklocal
+Set a flag to perform automatic link-local address configuration when
+the interface becomes avalilable.
+.It Cm -auto_linklocal
+Clear a flag
+.Cm auto_linklocal .
+.It Cm defaultif
+Set the specified interface as the default route when there is no
+default router.
+.It Cm -defaultif
+Clear a flag
+.Cm defaultif .
+.It Cm ifdisabled
+Set a flag to disable all of IPv6 network communications on the
+specified interface.
+.It Cm -ifdisabled
+Clear a flag
+.Cm ifdisabled .
+When this flag is cleared and 
+.Cm auto_linklocal
+flag is enabled, automatic configuration of a link-local address is
+performed.
+.It Cm nud
+Set a flag to enable Neighbor Unreachability Detection.
+.It Cm -nud
+Clear a flag
+.Cm nud .
+.It Cm prefer_source
+Set a flag to prefer addesses on the interface as candidates of the
+source address for outgoing packets.
+.It Cm -prefer_source
+Clear a flag
+.Cm prefer_source .
+.El
+.Pp
 The following parameters are specific to cloning
 IEEE 802.11 wireless interfaces with the
 .Cm create
@@ -2421,6 +2463,9 @@ from the interface
 .Li ed0 :
 .Dl # ifconfig ed0 inet 192.0.2.45 -alias
 .Pp
+Enable IPv6 functionality of the interface:
+.Dl # ifconfig em0 inet6 -ifdisabled
+.Pp
 Add the IPv6 address
 .Li 2001:DB8:DBDB::123/48
 to the interface
@@ -2475,12 +2520,13 @@ utility appeared in
 Basic IPv6 node operation requires a link-local address on each
 interface configured for IPv6.
 Normally, such an address is automatically configured by the
-kernel on each interface added to the system; this behaviour may
-be disabled by setting the sysctl MIB variable
-.Va net.inet6.ip6.auto_linklocal
-to 0.
+kernel on each interface added to the system or enabled; this behavior may
+be disabled by setting per-interface flag
+.Cm -auto_linklocal .
+The default value of this flag is 1 and can be disabled by using the sysctl
+MIB variable
+.Va net.inet6.ip6.auto_linklocal .
 .Pp
-If you delete such an address using
-.Nm ,
-the kernel may act very odd.
-Do this at your own risk.
+Do not configure IPv6 addresses with no link-local address by using
+.Nm .
+It can result in unexpected behaviors of the kernel.