[Openstack] DHCP for IPv6

Jorge Luiz Correa correajl at gmail.com
Thu Sep 28 00:13:44 UTC 2017


Hum, nice inspection.

Try to create rules that pass the IPv6 Multicast addresses and ICMPv6 protocol. These are the addresses used by IPv6.

FF02:0:0:0:0:0:1:2	All-dhcp-agents
FF05:0:0:0:0:0:1:3	All-dhcp-servers

I think all-dhcp-agents is sufficient.

https://www.iana.org/assignments/ipv6-multicast-addresses/ipv6-multicast-addresses.xhtml <https://www.iana.org/assignments/ipv6-multicast-addresses/ipv6-multicast-addresses.xhtml>

Regards


> On 27 Sep 2017, at 20:44, Sterdnot Shaken <sterdnotshaken at gmail.com> wrote:
> 
> So, after more digging, it appears DHCPv6 traffic coming from the test VM's is being dropped at the Security Group (Linux Bridge) enforcement point ... I can restart a VM's while doing a tcpdump on the respective tap interface for that VM and see DHCPv6 request packets being sent out as expected, but they never make it through the IPTables rules associated with the Linux Bridge that represents the Security Group assigned to the VM. Hopefully that makes sense.
> 
> The DHCPv6 packets seem to be getting dropped by the last IPTables Drop rule:
> 
> Chain neutron-openvswi-sd36b2151-0 (1 references)
>  pkts bytes target     prot opt in     out     source               destination
>     0     0 RETURN     all      *      *       2604:ba00:ffff:fff2::b  ::/0                 MAC FA:16:3E:05:C1:A3 /* Allow traffic from defined IP/MAC pairs. */
>     0     0 RETURN     all      *      *       fe80::f816:3eff:fe05:c1a3  ::/0                 MAC FA:16:3E:05:C1:A3 /* Allow traffic from defined IP/MAC pairs. */
>  6475  895K DROP       all      *      *       ::/0                 ::/0                 /* Drop traffic without an IP/MAC allow rule. */
> 
> We've tried creating new Security Groups that explicitly allow ports, but still no luck:
> 
> Ingress        IPv6     UDP     1 - 65535
> Egress         IPv6     UDP     1 - 65535
> 
> Any ideas?
> 
> Thanks!
> 
> Steve
> 
> 
> 
> On Tue, Sep 26, 2017 at 5:58 PM, Sterdnot Shaken <sterdnotshaken at gmail.com <mailto:sterdnotshaken at gmail.com>> wrote:
> Openstack version: Ocata
> Mech driver: OVS
> Security: Linuxbridge
> 
> Hello!
> 
> Anyone have any idea why DHCP for IPv4 works fine but DHCP for IPv6 doesn't? With Stateless or just SLAAC, the VM's calculate a correct IPv6 address from the IPv6 prefix I've assigned, but (for stateless) the instances doesn't get any of the options, like DNS, etc...  Stateful doesn't work at all. I configure a stateful network using a command like this:
> 
> openstack subnet create --allocation-pool start=2604:ffff:ffff:ffff::2,end=2604:ffff:ffff:ffff:ffff:ffff:ffff:ffff --ip-version 6 --ipv6-address-mode dhcpv6-stateful --ipv6-ra-mode dhcpv6-stateful --dns-nameserver 2620:0:ccc::2 --network cust01-v6_net0 --subnet-range 2604:ffff:ffff:ffff::/64 cust01-v6_sub0
> 
> But none of the instances added to that network acquire a v6 address ever. I can statically assign the selected IPv6 address to the respective instance and it can then ping out using v6 just fine. I can also add IPv6 DNS addresses to resolv.conf and the instance can correctly resolve as well. This issue happens on both Linux and Windows instances...
> 
> Any ideas?
> 
> Thanks in advance!
> 
> Steve
> 
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