Is accept_rtadv enabled by default?

[Thomas]

Hello

Out of pure curiosity. Why is accept_rtadv enabled by default on a
interface with ipv6? I did not define accept_rtadv in rc.conf nor is it
enabled via sysctl. net.inet6.ip6.accept_rtadv is set to 0 (default)

But it's enabled on my interface: nd6 options=3<PERFORMNUD,ACCEPT_RTADV>

root at gw:/etc# ifconfig em0
em0: flags=9843<UP,BROADCAST,RUNNING,SIMPLEX,LINK0,MULTICAST> metric 0
mtu 1500
	options=209b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC>
	ether 00:1b:21:1e:e0:58
	inet 82.220.2.120 netmask 0xfffffe00 broadcast 82.220.3.255
	inet6 fe80::21b:21ff:fe1e:e058%em0 prefixlen 64 scopeid 0x3
	inet6 2001:1680:2:100:2:120:a:b prefixlen 64
	nd6 options=3<PERFORMNUD,ACCEPT_RTADV>
	media: Ethernet autoselect (100baseTX <full-duplex>)
	status: active

I could not find any reference that ACCEPT_RTADV is enabled by default
in the ifconfig man page. Is this a bug?

I can disable it with ifconfig em0 inet6 -accept_rtadv and put
-accept_rtadv in rc.conf.

My system:
8.2-STABLE FreeBSD 8.2-STABLE #1: Mon May  2 10:08:30 UTC 2011

rc.conf:
ipv6_enable="YES"
ipv6_defaultrouter="2001:1680:2:100::1"
ipv6_ifconfig_em0="2001:1680:2:100:2:120:a:b prefixlen 64"
ipv6_firewall_enable="YES"
ipv6_firewall_type="OPEN"

sysctl ist set to 0:
net.inet6.ip6.accept_rtadv: 0

Regards,
Thomas