Date: Wed, 25 Nov 2009 16:07:45 +0100 From: <Hartmut.Brandt@dlr.de> To: <Hartmut.Brandt@dlr.de>, <freebsd-net@freebsd.org> Subject: RE: Need help on IPv6 prefixes and interface addresses Message-ID: <E086A96846579E4F932C168218DB1E55024129@exbe5.intra.dlr.de> References: <E086A96846579E4F932C168218DB1E55024128@exbe5.intra.dlr.de>
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To answer my own question :-) These strange link local addresses are =
explained in the developers handbook section 8.1.1.3 and are called =
embedded
link local addresses. These are not standard IPv6 addresses, but a way =
to encode the interface index (aka zone index) into the IPv6 address. =
This must be undone by the user program before using these addresses.
harti=20
-----Original Message-----
From: owner-freebsd-net@freebsd.org on behalf of Hartmut.Brandt@dlr.de
Sent: Wed 11/25/2009 1:15 PM
To: freebsd-net@freebsd.org
Subject: Need help on IPv6 prefixes and interface addresses
=20
Hi all,
I try to make bsnmpd IPv6 aware and need some help here. I've set up a =
small IPv6 network for testing between a couple of VMs.
For IPv6 interface addresses there are two tables: ipAddressPrefix table =
and ipAddressTable (containing pointers to the prefix table). Now I see =
something on my system I cannot grasp. ndp -pn gives me:
2001:638:101:ff::/64 if=3Dle0
flags=3DLO vltime=3Dinfinity, pltime=3Dinfinity, expire=3DNever, ref=3D1
No advertising router
fe80::%le0/64 if=3Dle0
flags=3DLAO vltime=3Dinfinity, pltime=3Dinfinity, expire=3DNever, =
ref=3D0
No advertising router
fe80::%lo0/64 if=3Dlo0
flags=3DLAO vltime=3Dinfinity, pltime=3Dinfinity, expire=3DNever, =
ref=3D0
No advertising router
ifconfig -a inet6 gives:
le0: flags=3D8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu =
1500
options=3D8<VLAN_MTU>
inet6 fe80::20c:29ff:fe90:dd1b%le0 prefixlen 64 scopeid 0x1=20
inet6 2001:638:101:ff::8:ffff prefixlen 64=20
lo0: flags=3D8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
options=3D3<RXCSUM,TXCSUM>
inet6 ::1 prefixlen 128=20
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2=20
So far, so nice.
When I ask for the interface addresses via sysctl([0, NET_RT_IFLIST, 0], =
...) I get strange RTM_NEWADDR messages:
msglen=3D76 version=3D5 type=3DRTM_NEWADDR
flags=3D0
index=3D1 metric=3D0
netmask=3DINET6,28,{0,0,ffff:ffff:ffff:ffff::,0}
ifa=3DINET6,28,{0,0,fe80:1::20c:29ff:fe90:dd1b,0}
Which means a prefix of fe80:1::/64 instead of fe80::%le0/64. Note, the =
:1: there and note the zero missing scope_id
(the last 0 inside the {}). Same for lo0:
msglen=3D80 version=3D5 type=3DRTM_NEWADDR
flags=3D0
index=3D2 metric=3D0
netmask=3DINET6,28,{0,0,ffff:ffff:ffff:ffff::,0}
ifa=3DINET6,28,{0,0,fe80:2::1,0}
brd=3DUNSPEC,0,{}
So my questions:
- are the routing message really that inconsistent and broken? Or do I =
read them somehow incorrect?
- is it possible to rely on the prefix table? In other words: Does =
*each* prefix used
in a INET6 interface address appear in the prefix list?
harti
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