[Dnsmasq-discuss] clients of DHCPv6 with constructed IPv6 address range are not notified on address range change

Simon Kelley simon at thekelleys.org.uk
Wed Sep 19 00:24:59 BST 2018


On 18/09/18 23:03, line wrap clean up wrote:

> Strange thing: sometimes after reconnect I can observe expected behaviour
> (like you described it, see log 1), sometimes not (SLAAC-CONFIRM is missing,
> see log 2)
> 
> ---------- log1 --------
> Sep 17 20:22:45 rtr dnsmasq-dhcp[7855]: DHCPv6 stateless on 2001:16b8:2284:f5fc::, constructed for lan0
> Sep 17 20:22:45 rtr dnsmasq-dhcp[7855]: DHCPv4-derived IPv6 names on 2001:16b8:2284:f5fc::, constructed for lan0
> Sep 17 20:22:45 rtr dnsmasq-dhcp[7855]: router advertisement on 2001:16b8:2284:f5fc::, constructed for lan0
> Sep 17 20:22:45 rtr dnsmasq-dhcp[7855]: DHCPv6 stateless on 2001:16b8:2284:f5fd::, constructed for dmz0
> Sep 17 20:22:45 rtr dnsmasq-dhcp[7855]: DHCPv4-derived IPv6 names on 2001:16b8:2284:f5fd::, constructed for dmz0
> Sep 17 20:22:45 rtr dnsmasq-dhcp[7855]: router advertisement on 2001:16b8:2284:f5fd::, constructed for dmz0
> Sep 17 20:22:45 rtr dnsmasq[7855]: reading /etc/dnsmasq-resolv.conf

> ---------- log2 --------
> Sep 18 04:35:20 rtr dnsmasq-dhcp[7855]: DHCPv6 stateless on 2001:16b8:22c4:83fc::, constructed for lan0
> Sep 18 04:35:20 rtr dnsmasq-dhcp[7855]: DHCPv4-derived IPv6 names on 2001:16b8:22c4:83fc::, constructed for lan0
> Sep 18 04:35:20 rtr dnsmasq-dhcp[7855]: router advertisement on 2001:16b8:22c4:83fc::, constructed for lan0
> Sep 18 04:35:20 rtr dhcpcd[15081]: lan0: waiting for DHCPv6 DAD to complete
> Sep 18 04:35:20 rtr dhcpcd[15081]: dmz0: adding address 2001:16b8:22c4:83fd::1/64
> Sep 18 04:35:20 rtr dhcpcd[15081]: dmz0: pltime 3600 seconds, vltime 7200 seconds
> Sep 18 04:35:20 rtr dnsmasq-dhcp[7855]: DHCPv6 stateless on 2001:16b8:22c4:83fd::, constructed for dmz0
> Sep 18 04:35:20 rtr dnsmasq-dhcp[7855]: DHCPv4-derived IPv6 names on 2001:16b8:22c4:83fd::, constructed for dmz0
> Sep 18 04:35:20 rtr dnsmasq-dhcp[7855]: router advertisement on 2001:16b8:22c4:83fd::, constructed for dmz0
> Sep 18 04:35:20 rtr dhcpcd[15081]: dmz0: waiting for DHCPv6 DAD to complete
> Sep 18 04:35:20 rtr dhcpcd[15081]: lan0: adding route to 2001:16b8:22c4:83fc::/64
> Sep 18 04:35:20 rtr dhcpcd[15081]: dmz0: adding route to 2001:16b8:22c4:83fd::/64
> Sep 18 04:35:20 rtr dhcpcd[15081]: wan0: executing `/usr/lib/dhcpcd/dhcpcd-run-hooks' BOUND6
> Sep 18 04:35:20 rtr dnsmasq-dhcp[7855]: DHCPINFORMATION-REQUEST(lan0) 00:02:00:00:ab:11:d5:97:98:17:01:41:27:3e
> Sep 18 04:35:20 rtr dnsmasq-dhcp[7855]: DHCPINFORMATION-REQUEST(dmz0) 00:02:00:00:ab:11:9b:74:21:c0:e9:5d:1c:18
> Sep 18 04:35:20 rtr dnsmasq-dhcp[7855]: DHCPINFORMATION-REQUEST(lan0) 00:02:00:00:ab:11:ee:62:d8:4d:ca:9f:9d:d5
> Sep 18 04:35:20 rtr dhcpcd[15081]: wan0: Router Advertisement DAD completed
> Sep 18 04:35:20 rtr dhcpcd[15081]: wan0: executing `/usr/lib/dhcpcd/dhcpcd-run-hooks' ROUTERADVERT
> Sep 18 04:35:21 rtr ddclient[1597]: SUCCESS:  updating rtrhomevak.spdns.de: good: IP address set to 2001:16b8:22c4:8300>
> Sep 18 04:35:21 rtr dhcpcd[15081]: dmz0: DHCPv6 DAD completed
> Sep 18 04:35:21 rtr dhcpcd[15081]: dmz0: executing `/usr/lib/dhcpcd/dhcpcd-run-hooks' DELEGATED6
> Sep 18 04:35:21 rtr dhcpcd[15081]: lan0: DHCPv6 DAD completed
> Sep 18 04:35:21 rtr dhcpcd[15081]: lan0: executing `/usr/lib/dhcpcd/dhcpcd-run-hooks' DELEGATED6
> Sep 18 04:35:29 rtr dnsmasq-dhcp[7855]: RTR-ADVERT(lan0) 2001:16b8:22c4:83fc::



If you look, lots of things are different between the two logs. In the
second one, dhcpcd is doing routing table changes, for instance. That
could explain why dnsmasq gives up trying to confirm SLAAC addresses
because it gets transient "no route to host" returns. (see previous
reply to make sense of this.)


Simon.



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