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, 8 insertions, 2 deletions

diff --git a/share/man/man4/inet6.4 b/share/man/man4/inet6.4
index 27b0876..dad5ccf8 100644
--- a/share/man/man4/inet6.4
+++ b/share/man/man4/inet6.4
@@ -29,7 +29,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd January 29, 1999
+.Dd September 2, 2009
 .Dt INET6 4
 .Os
 .Sh NAME
@@ -307,7 +307,8 @@ Integer: default maximum number of fragmented packets the node will accept.
 The flag is provided basically for avoiding possible DoS attacks.
 .It Dv IPV6CTL_ACCEPT_RTADV
 .Pq ip6.accept_rtadv
-Boolean: enable/disable receiving of
+Boolean: the default value of a per-interface flag to
+enable/disable receiving of
 .Tn ICMPv6
 router advertisement packets,
 and autoconfiguration of address prefixes and default routers.
@@ -315,6 +316,11 @@ The node must be a host
 (not a router)
 for the option to be meaningful.
 Defaults to off.
+.It Dv IPV6CTL_AUTO_LINKLOCAL
+.Pq ip6.auto_linklocal
+Boolean: the default value of a per-interface flag to
+enable/disable performing automatic link-local address configuration.
+Defaults to on.
 .It Dv IPV6CTL_KEEPFAITH
 .Pq ip6.keepfaith
 Boolean: enable/disable