[Dnsmasq-discuss] ipv6 slaac or stateless - No address or no address range available

[Simon Kelley]

On 25/02/2023 16:19, Daniel via Dnsmasq-discuss wrote:
> Hi,
> 
> I'm banging my head with a KVM VM only ipv6 who can't get stateless 
> dhcpv6 address. Always getting messages like shown below:
> 
> Configuration being
> 
> enable-ra
> ra-param=lan,high,60,60
> dhcp-range=set:computer6,::0,::ffff,constructor:lan,ra-stateless,ra-names,1h
> dhcp-option=tag:computer6,option6:3,fd99:1234:beef:cafe::2
> dhcp-option=tag:computer6,option6:6,fd99:1234:beef:cafe::1
> dhcp-option=tag:computer6,option6:ntp-server,fd99:1234:beef:cafe::2
> 
> Starting dnsmasq I get in logs
> 
> Feb 25 16:52:38 dnsmasq[211076]: demarré, version 2.85 (taille de cache 
> 2048)
> [...]
> Feb 25 16:52:38 dnsmasq-dhcp[211076]: DHCPv6 sans état (stateless) sur lan
> Feb 25 16:52:38 dnsmasq-dhcp[211076]: noms IPv6 dérivés de DHCPv4 sur lan
> Feb 25 16:52:38 dnsmasq-dhcp[211076]: annonces de routeurs sur lan
> 
> Feb 25 16:52:38 dnsmasq-dhcp[211076]: annonces de routeur IPv6 activées
> 
> [...]
> Feb 25 16:53:09 dnsmasq-dhcp[211076]: pas de plage d'adresse disponible 
> pour la requête DHCPv6 via lan
> 
> or configuration being
> 
> enable-ra
> ra-param=lan,high,60,60
> dhcp-range=set:computer6,fd99:1234:beef:cafe::0,fd99:1234:beef:cafe::ffff,slaac,ra-names,1h
> dhcp-option=tag:computer6,option6:3,fd99:1234:beef:cafe::2
> dhcp-option=tag:computer6,option6:6,fd99:1234:beef:cafe::1
> dhcp-option=tag:computer6,option6:ntp-server,fd99:1234:beef:cafe::2
> 
> Feb 25 17:10:32 dnsmasq[214786]: demarré, version 2.85 (taille de cache 
> 2048)
> [...]
> Feb 25 17:10:32 dnsmasq-dhcp[214786]: DHCPv6, plage d'adresses IP 
> fd99:1234:beef:cafe:: -- fd99:1234:beef:cafe::ffff, durée de bail 1h
> Feb 25 17:10:32 dnsmasq-dhcp[214786]: noms IPv6 dérivés de DHCPv4 sur 
> fd99:1234:beef:cafe::
> Feb 25 17:10:32 dnsmasq-dhcp[214786]: annonces de routeurs sur 
> fd99:1234:beef:cafe::
> Feb 25 17:10:32 dnsmasq-dhcp[214786]: annonces de routeur IPv6 activées
> [...]
> Feb 25 17:11:37 dnsmasq-dhcp[214786]: DHCPSOLICIT(lan) 
> 00:01:00:01:27:b4:3b:4d:52:54:00:e5:33:8a
> Feb 25 17:11:37 dnsmasq-dhcp[214786]: DHCPREPLY(lan) 
> 00:01:00:01:27:b4:3b:4d:52:54:00:e5:33:8a pas d'adresse disponible
> 
> Interface lan is a bridge of eth0 if it matter.
> 
> Any clue on whats going on here ? Thanks for your support.

"Stateless" dhcpv6 means using DHCP just to get configuration 
information, NOT allocating an address. The host is supposed to get its 
addresses via the router advertisements and use the DHCP request just to 
find DNS servers and other configuration. This all got a bit superseded 
when the IETF started defining options on the RA packets for the common 
configuration options.

TLDR; If you want your host to get an address via DHCPv6, don't 
configure stateless DHCP.

Cheers,

Simon.