IPv6 and DHCP not working

somercet · 2014-07-13 16:45:28

We complain so often about how we can't have nice things, so here's something nice I apparently have but cannot enjoy:

I have Comcast and I'm in an IPv6 area. (Yay.) When I boot with a recent Arch install CD, my computer, plugged directly into the cable modem, acquires IPv4 and IPv6 addresses using dhcpcd. Booting from the disk, I get no such luck.

I am running Arch with testing repos enabled, everything up to date.

atom ~ # ip addr

2: enp63s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 00:19:bb:5f:ba:99 brd ff:ff:ff:ff:ff:ff

atom ~ # dhcpcd enp63s0
dhcpcd[3334]: version 6.4.0 starting
dhcpcd[3334]: enp63s0: adding address fe80::219:bbff:fe5f:ba99
dhcpcd[3334]: enp63s0: waiting for carrier
dhcpcd[3334]: enp63s0: carrier acquired
dhcpcd[3334]: DUID 00:01:00:01:19:5d:a1:e1:6c:62:6d:ce:db:c1
dhcpcd[3334]: enp63s0: IAID bb:5f:ba:99
dhcpcd[3334]: enp63s0: soliciting an IPv6 router
dhcpcd[3334]: enp63s0: soliciting a DHCP lease
dhcpcd[3334]: enp63s0: offered 24.11.164.108 from 69.252.72.4
dhcpcd[3334]: enp63s0: Router Advertisement from fe80::201:5cff:fe65:46
dhcpcd[3334]: enp63s0: soliciting a DHCPv6 lease
dhcpcd[3334]: enp63s0: leased 24.11.164.108 for 268336 seconds
dhcpcd[3334]: enp63s0: adding route to 24.11.160.0/21
dhcpcd[3334]: enp63s0: adding default route via 24.11.160.1
dhcpcd[3475]: enp63s0: MTU set to 576
dhcpcd[3334]: forked to background, child pid 3512

If I run it first thing after boot, using "-6" flag, it works for IPv6 only. Running "dhcpcd -6" after acquiring a v4 address gives me:

dhcpcd[3581]: enp63s0: IPv6 kernel autoconf disabled

Any ideas? dhclient does the same thing, so itmay be an Arch, systemd or other boot-related mechanism. Yes, and I read the IPv6 wiki.

Last edited by somercet (2014-07-13 17:26:49)

WonderWoofy · 2014-07-13 19:47:58

Have you tried with any other tool besides dhcpcd? I use comcast's ipv6 with systemd-networkd from my openwrt router, and all works just fine.

rsmarples · 2014-07-13 22:10:14

somercet wrote:

We complain so often about how we can't have nice things, so here's something nice I apparently have but cannot enjoy:
I have Comcast and I'm in an IPv6 area. (Yay.) When I boot with a recent Arch install CD, my computer, plugged directly into the cable modem, acquires IPv4 and IPv6 addresses using dhcpcd. Booting from the disk, I get no such luck.
I am running Arch with testing repos enabled, everything up to date.
atom ~ # ip addr

2: enp63s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 00:19:bb:5f:ba:99 brd ff:ff:ff:ff:ff:ff

atom ~ # dhcpcd enp63s0
dhcpcd[3334]: version 6.4.0 starting
dhcpcd[3334]: enp63s0: adding address fe80::219:bbff:fe5f:ba99
dhcpcd[3334]: enp63s0: waiting for carrier
dhcpcd[3334]: enp63s0: carrier acquired
dhcpcd[3334]: DUID 00:01:00:01:19:5d:a1:e1:6c:62:6d:ce:db:c1
dhcpcd[3334]: enp63s0: IAID bb:5f:ba:99
dhcpcd[3334]: enp63s0: soliciting an IPv6 router
dhcpcd[3334]: enp63s0: soliciting a DHCP lease
dhcpcd[3334]: enp63s0: offered 24.11.164.108 from 69.252.72.4
dhcpcd[3334]: enp63s0: Router Advertisement from fe80::201:5cff:fe65:46
dhcpcd[3334]: enp63s0: soliciting a DHCPv6 lease
dhcpcd[3334]: enp63s0: leased 24.11.164.108 for 268336 seconds
dhcpcd[3334]: enp63s0: adding route to 24.11.160.0/21
dhcpcd[3334]: enp63s0: adding default route via 24.11.160.1
dhcpcd[3475]: enp63s0: MTU set to 576
dhcpcd[3334]: forked to background, child pid 3512
If I run it first thing after boot, using "-6" flag, it works for IPv6 only. Running "dhcpcd -6" after acquiring a v4 address gives me:
dhcpcd[3581]: enp63s0: IPv6 kernel autoconf disabled
Any ideas? dhclient does the same thing, so itmay be an Arch, systemd or other boot-related mechanism. Yes, and I read the IPv6 wiki.

From what you have posted, nothing looks wrong.
dhcpcd forks to the background when it gets a DHCP lease, or an RA with DNS, or a DHCPv6 lease.
So in your log, dhcpcd received an RA with an instruction to solicit a DHCPv6 lease and then forked after getting a DHCP lease.
Hopefully the syslogs will show dhcpcd obtaining the DHCPv6 lease in the background.

You can also test this like so, by keeping dhcpcd in the foreground with debugging.

dhcpcd -x
dhcpcd -dB

For reference, dhcpcd-6.4.0 ships with private IPv6 SLAAC addressing by default which means it will take over the kernel RS/RA as the kernel does not support this valued RFC.

nomorewindows · 2014-07-13 23:36:40

The IPv6 address you are getting looks to be just stateless IP6. It isn't being routed using a live IP, but a local network only IP.

rsmarples · 2014-07-14 08:21:28

nomorewindows wrote:

The IPv6 address you are getting looks to be just stateless IP6. It isn't being routed using a live IP, but a local network only IP.

Eh? We don't know that.
At most from the above he received an RA which may or may not have the AutoConf bit on.
It did have the M bit set though as we can see dhcpcd attemtping to solicit a stateful DHCPv6 address.
But we don't know from the logs if it worked or not.

nomorewindows · 2014-07-14 12:43:49

rsmarples wrote:

nomorewindows wrote:
The IPv6 address you are getting looks to be just stateless IP6. It isn't being routed using a live IP, but a local network only IP.
Eh? We don't know that.
At most from the above he received an RA which may or may not have the AutoConf bit on.
It did have the M bit set though as we can see dhcpcd attemtping to solicit a stateful DHCPv6 address.
But we don't know from the logs if it worked or not.

Do a ifconfig, but the fe80:: that's a local stateless address.
You can ping everything on your network with ping6 ff02::1%<interface> , but if you ping6 google.com, it won't work, because ip6 is not setup correctly.

rsmarples · 2014-07-14 13:12:49

nomorewindows wrote:

rsmarples wrote:
nomorewindows wrote:
The IPv6 address you are getting looks to be just stateless IP6. It isn't being routed using a live IP, but a local network only IP.
Eh? We don't know that.
At most from the above he received an RA which may or may not have the AutoConf bit on.
It did have the M bit set though as we can see dhcpcd attemtping to solicit a stateful DHCPv6 address.
But we don't know from the logs if it worked or not.
Do a ifconfig, but the fe80:: that's a local stateless address.
You can ping everything on your network with ping6 ff02::1%<interface> , but if you ping6 google.com, it won't work, because ip6 is not setup correctly.

I know what a stateless and link-local address are ... he didn't include one in his logs or output.

nomorewindows · 2014-07-14 14:34:14

rsmarples wrote:

nomorewindows wrote:
rsmarples wrote:
Eh? We don't know that.
At most from the above he received an RA which may or may not have the AutoConf bit on.
It did have the M bit set though as we can see dhcpcd attemtping to solicit a stateful DHCPv6 address.
But we don't know from the logs if it worked or not.
Do a ifconfig, but the fe80:: that's a local stateless address.
You can ping everything on your network with ping6 ff02::1%<interface> , but if you ping6 google.com, it won't work, because ip6 is not setup correctly.
I know what a stateless and link-local address are ... he didn't include one in his logs or output.

But both addresses OP post were fe80::

Arch Linux

#1 2014-07-13 16:45:28

IPv6 and DHCP not working

#2 2014-07-13 19:47:58

Re: IPv6 and DHCP not working

#3 2014-07-13 22:10:14

Re: IPv6 and DHCP not working

#4 2014-07-13 23:36:40

Re: IPv6 and DHCP not working

#5 2014-07-14 08:21:28

Re: IPv6 and DHCP not working

#6 2014-07-14 12:43:49

Re: IPv6 and DHCP not working

#7 2014-07-14 13:12:49

Re: IPv6 and DHCP not working

#8 2014-07-14 14:34:14

Re: IPv6 and DHCP not working

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