[Dnsmasq-discuss] Cannot assign IPv6 address for /96 subnet

[Sheng Yang]

Hi Simon,

I found I can't assign IPv6 address for /96 subnet.

I specified DHCP range use 96 bits prefixes:

dhcp-range=fc00:3:1602::7473,96,static

And here is nic:

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
state UP qlen 1000
    link/ether 06:8a:42:00:00:2f brd ff:ff:ff:ff:ff:ff
    inet6 fc00:3:1602::7473/96 scope global
       valid_lft forever preferred_lft forever
    inet6 fe80::48a:42ff:fe00:2f/64 scope link
       valid_lft forever preferred_lft forever

I've enabled logdhcp, but didn't see anything in the log after restart
the dnsmasq except loading configurations info.

TCPDUMP shows:

02:54:53.695350 IP6 fe80::44f:66ff:fe00:2e.dhcpv6-client >
ff02::1:2.dhcpv6-server: dhcp6 solicit
02:54:54.726548 IP6 fe80::44f:66ff:fe00:2e.dhcpv6-client >
ff02::1:2.dhcpv6-server: dhcp6 solicit
02:54:56.838944 IP6 fe80::44f:66ff:fe00:2e.dhcpv6-client >
ff02::1:2.dhcpv6-server: dhcp6 solicit

More detail:
02:55:57.448471 IP6 (hlim 1, next-header UDP (17) payload length: 73)
fe80::44f:66ff:fe00:2e.dhcpv6-client > ff02::1:2.dhcpv6-server: [udp
sum ok] dhcp6 solicit (xid=4157d (client-ID hwaddr type 1
064f6600002e) (option-request DNS-name Client-FQDN DNS NTP-Server)
(elapsed-time 101) (Client-FQDN) (IA_NA IAID:1711276078 T1:3600
T2:5400))
0x0000:  3333 0001 0002 064f 6600 002e 86dd 6000
0x0010:  0000 0049 1101 fe80 0000 0000 0000 044f
0x0020:  66ff fe00 002e ff02 0000 0000 0000 0000
0x0030:  0000 0001 0002 0222 0223 0049 4b0e 0104
0x0040:  157d 0001 000a 0003 0001 064f 6600 002e
0x0050:  0006 0008 0018 0027 0017 001f 0008 0002
0x0060:  0065 0027 0009 0006 7562 756e 7475 0000
0x0070:  0300 0c66 0000 2e00 000e 1000 0015 18

Seems valid.

If I didn't specify "96" in the dhcp-range line, it would complains:

Feb  9 02:57:15 dnsmasq-dhcp[2134]: no address range available for
DHCPv6 request via eth0

I don't know which part of setup is wrong. Probably due to link local
address is /64?

Thanks in advance!

--Sheng