Heads up: impending IPv6 Test Day

[Bernd Stramm]

On Thu, 2 Jun 2011 17:07:47 +0100
"Richard W.M. Jones" <rjones at redhat.com> wrote:

> On Thu, Jun 02, 2011 at 06:00:44PM +0200, Björn Persson wrote:
> > Daniel P. Berrange wrote:
> > > On Thu, Jun 02, 2011 at 04:40:10PM +0100, Richard W.M. Jones
> > > wrote:
> > > > The Linux machines on my LAN appear to have acquired IPv6
> > > > addresses, eg:
> > > > 
> > > > $ ip addr show eth0
> > > > 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc
> > > > pfifo_fast state UNKNOWN qlen 1000
> > > > 
> > > >     link/ether 00:e0:81:74:02:28 brd ff:ff:ff:ff:ff:ff
> > > >     inet 192.168.0.128/24 brd 192.168.0.255 scope global eth0
> > > >     inet6 fe80::2e0:81ff:fe74:228/64 scope link
> > > >     
> > > >        valid_lft forever preferred_lft forever
> > > > 
> > > > but pinging them gives me strange errors:
> > > > 
> > > > $ ping6 fe80::2e0:81ff:fe74:228/64
> > > > unknown host
> > > > $ ping6 fe80::2e0:81ff:fe74:228
> > > > connect: Invalid argument
> > > > $ ping6 fe80::2e0:81ff:fe74
> > > > connect: Invalid argument
> > > 
> > > Anything with an  fe80:: prefix is a link local address, which
> > > is only unique within the scope of a single LAN segment. Thus
> > > if you want to send traffic to such addresses, you need to specify
> > > the NIC to send the traffic out from. The vast majority of apps
> > > using sockets have no way to let you do this.
> > 
> > Ping6 has a way though:
> > 
> > $ ping6 -I eth0 fe80::200:24ff:fec9:2e0c
> > PING fe80::200:24ff:fec9:2e0c(fe80::200:24ff:fec9:2e0c) from 
> > fe80::21e:8cff:fecf:cde5 eth0: 56 data bytes
> > 64 bytes from fe80::200:24ff:fec9:2e0c: icmp_seq=1 ttl=64 time=1.69
> > ms 64 bytes from fe80::200:24ff:fec9:2e0c: icmp_seq=2 ttl=64
> > time=0.263 ms
> 
> But that's not so useful if no other programs can use these addresses.
> Is there a way to assign "proper" addresses?  Just run radvd and
> configure it with a random prefix?

Instead of random, you may want to use a Unique Local Address prefix,
following
http://www.ripe.net/lir-services/resource-management/ipv6/ipv6-address-types

> 
> Rich.
> 



-- 
Bernd Stramm
bernd.stramm at gmail.com