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#1 2013-03-18 21:25:48

janoliver
Member
Registered: 2011-06-01
Posts: 49

[solved] IPv6 Doesn't work.

Hi.

I am trying to get simple IPv6 to work. My ISP's modem shows the following information: (Note, that the sequence XXX:XXX is equal)

Global IPv6 Address:	 ***:***:da00:1:740f:25db:ce00:43c7/128
Link-Local IPv6 Address:	 fe80::bec8:10ff:fef4:773c/64
IPv6 Gateway:	 fe80::8a43:e1ff:fe37:bfd9
DNS IPv6 1:	 XXX:XXX:2:1107::11
DNS IPv6 2:	 XXX:XXX:2:1109::11
DNS IPv6 3:	 ::

DS-Lite Configuration	 	 
AFTR Address:	 XXX:XXX::4065
AFTR Domain Name:	 de-fra04a-aftr1.unity-media.net

LAN IPv6 Prefix:	 XXX:XXX:da1a:4f00::/56

I know very little about IPv6, but as far as I understand, this means that I can distribute the IP addresses of the LAN IPv6 prefix to my liking and would have to use the "IPv6 Gateway" as a gateway in connections.

My arch box is sitting behind the router, being connected via the interface "enp1s0" to it. I have the following netcfg profile:

CONNECTION='ethernet'
DESCRIPTION='A basic static ethernet connection using iproute'
INTERFACE='enp1s0'
IP='static'
ADDR='192.168.0.4'
GATEWAY='192.168.0.1'

IP6='static'
ADDR6=('XXX:XXX:da1a:4f00::/56')
GATEWAY6='fe80::bec8:10ff:fef4:773c'

Now, ping6 doesn't work.

# ping6 ipv6.google.com     
PING ipv6.google.com(zrh04s05-in-x14.1e100.net) 56 data bytes
^X^C
--- ipv6.google.com ping statistics ---
8 packets transmitted, 0 received, 100% packet loss, time 6999ms

Some information:

# ip addr show dev enp1s0 
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:22:4d:a4:22:88 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.4/24 brd 192.168.0.255 scope global enp1s0
    inet6 XXX:XXX:da1a:4f00::/56 scope global 
       valid_lft forever preferred_lft forever
    inet6 fe80::222:4dff:fea4:2288/64 scope link 
       valid_lft forever preferred_lft forever
# traceroute ipv6.google.com
traceroute to ipv6.google.com (2a00:1450:400a:804::1014), 30 hops max, 80 byte packets
 1  * * *
 2  * * *
 3  * * *
 4  * * *
 5  * * *
 6  * 
...

I can ping myself.

What am I understanding wrong? What do I have to do to make outgoing IPv6 traffic, like ping6, work?

Thank you!

PS: analyzing tcpdumps, I saw that the router advertises itself with the address I set as gateway.

Last edited by janoliver (2013-03-19 08:32:45)

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#2 2013-03-18 23:00:31

fukawi2
Forum Moderator
From: .vic.au
Registered: 2007-09-28
Posts: 5,298
Website

Re: [solved] IPv6 Doesn't work.

IP6='static'
ADDR6=('XXX:XXX:da1a:4f00::/56')

You've set your address to the prefix; like setting your address to 192.168.0.0/24. Try changing that to XXX:XXX:da1a:4f00::1/56. Also, IPv6 networks should be /64, not /56 so your router is configured wrong. You should try and change that to use a /64

Are you able to ping fe80::bec8:10ff:fef4:773c? Looking at the output you've posted, it looks like that is the LL address on the ISP side of the modem, not the LAN side (ie, ppp0, not eth0 on the modem)XXX:XXX:da1a:4f00::/56'

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#3 2013-03-19 07:28:50

janoliver
Member
Registered: 2011-06-01
Posts: 49

Re: [solved] IPv6 Doesn't work.

Hi, as far as I know, XXX:XXX:da1a:4f00:: is a valid IP address itself. Setting that to ...::1 doesn't help.

Prefixes can have arbitrary (?) size, so 56 and sometimes 48 are valid numbers.

The fe80:..., as far as I understood, is a link related address. Maybe like the old 192.168... One can not ping it, I don't know why. It is described here.

The modem has docsis cable connection on the other side and I only have access to its web interface. The tcpdumps, however, should show me the correct address, no?

//E: It works now, I had to disable ipv6 forwarding in sysctl to enable stateless auto configuration of the interface. With that, I was able to find out the correct settings for IP6='static' in netcfg.

Last edited by janoliver (2013-03-19 08:32:32)

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#4 2013-03-19 23:08:16

fukawi2
Forum Moderator
From: .vic.au
Registered: 2007-09-28
Posts: 5,298
Website

Re: [solved] IPv6 Doesn't work.

janoliver wrote:

Hi, as far as I know, XXX:XXX:da1a:4f00:: is a valid IP address itself. Setting that to ...::1 doesn't help.

I believe you may be correct, but for debugging it couldn't hurt to make sure.

janoliver wrote:

Prefixes can have arbitrary (?) size, so 56 and sometimes 48 are valid numbers.

Yes, prefixes can be anything, and usually anything from /32 to /64, but an individual network should always be /64.

janoliver wrote:

The fe80:..., as far as I understood, is a link related address. Maybe like the old 192.168... One can not ping it, I don't know why. It is described here.

fe80::/10 is Link Local addresses. They are non-routable, but are pingable on the same link-layer (ie, LAN), unless the host is specifically blocking ICMPv6 echo-requests. It's completely different to RFC1918 (192.168.0.0/16 etc)

janoliver wrote:

The modem has docsis cable connection on the other side and I only have access to its web interface. The tcpdumps, however, should show me the correct address, no?

Depending where the tcpdumps were taken, yes. So if the router is advertising itself with the address fe80::bec8:10ff:fef4:773c then you should be able to ping that address, and use it as your gateway. As you've found, enabling auto-configuration uses the data in those RA's from the router to configure everything correctly.

Last edited by fukawi2 (2013-03-19 23:08:36)

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