default route via SLAAC not working ?

[Trond Endrestøl]

On Mon, 31 Jul 2017 10:34-0400, Mike Tancsa wrote:

> Not sure if this is the client or the router (an LTE modem) or some
> option on the FreeBSD client, but I am not getting the inet6 default
> route installed when I pick up an IP6 addr at boot time.  Looking at the
> pcap at the start, I see the following exchange
> 
> 
> 10:05:51.261641 a4:71:74:2b:c1:37 > 33:33:00:00:00:01, ethertype IPv6
> (0x86dd), length 118: (hlim 255, next-header ICMPv6 (58) payload length:
> 64) fe80::a671:74ff:fe2b:c137 > ff02::1: [icmp6 sum ok] ICMP6, router
> advertisement, length 64
>         hop limit 64, Flags [managed, other stateful], pref high, router
> lifetime 1800s, reachable time 0s, retrans time 0s
>           prefix info option (3), length 32 (4):
> 2605:8d80:6e3:7365::/64, Flags [onlink, auto], valid time 7200s, pref.
> time 3600s
>             0x0000:  40c0 0000 1c20 0000 0e10 0000 0000 2605
>             0x0010:  8d80 06e3 7365 0000 0000 0000 0000
>           mtu option (5), length 8 (1):  1460
>             0x0000:  0000 0000 05b4
>           source link-address option (1), length 8 (1): a4:71:74:2b:c1:37
>             0x0000:  a471 742b c137
> 10:05:51.926817 0c:5b:8f:27:9a:64 > 33:33:ff:27:9a:64, ethertype IPv6
> (0x86dd), length 86: (hlim 255, next-header ICMPv6 (58) payload length:
> 32) :: > ff02::1:ff27:9a64: [icmp6 sum ok] ICMP6, neighbor solicitation,
> length 32, who has 2605:8d80:6e3:7365:e5b:8fff:fe27:9a64
>           unknown option (14), length 8 (1):
>             0x0000:  0387 5e45 437d
> 
> 
> And I have the IP6 addr assigned.
> 
> ue0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
>         ether 0c:5b:8f:27:9a:64
>         hwaddr 0c:5b:8f:27:9a:64
>         inet6 fe80::e5b:8fff:fe27:9a64%ue0 prefixlen 64 scopeid 0x7
>         inet 192.168.8.100 netmask 0xffffff00 broadcast 192.168.8.255
>         inet6 2605:8d80:6e3:7365:e5b:8fff:fe27:9a64 prefixlen 64 autoconf
>         nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
> 
> 
> But no default route ? Is this something the client has to ask for ?
> Unfortunately, on the little USB LTE modem, there are no options to
> fiddle with ipv6 settings.
> 
> 
> # netstat -anr -6
> Routing tables
> 
> Internet6:
> Destination                       Gateway                       Flags
>   Netif Expire
> ::/96                             ::1                           UGRS
>    lo0
> ::1                               link#6                        UH
>    lo0
> ::ffff:0.0.0.0/96                 ::1                           UGRS
>    lo0
> 2605:8d80:6e3:7365::/64           link#7                        U
>    ue0
> 2605:8d80:6e3:7365:e5b:8fff:fe27:9a64 link#7                        UHS
>        lo0
> fe80::/10                         ::1                           UGRS
>    lo0
> fe80::%lo0/64                     link#6                        U
>    lo0
> fe80::1%lo0                       link#6                        UHS
>    lo0
> fe80::%ue0/64                     link#7                        U
>    ue0
> fe80::e5b:8fff:fe27:9a64%ue0      link#7                        UHS
>    lo0
> ff01::%lo0/32                     ::1                           U
>    lo0
> ff01::%ue0/32                     fe80::e5b:8fff:fe27:9a64%ue0  U
>    ue0
> ff02::/16                         ::1                           UGRS
>    lo0
> ff02::%lo0/32                     ::1                           U
>    lo0
> ff02::%ue0/32                     fe80::e5b:8fff:fe27:9a64%ue0  U
>    ue0

I haven't tried USB Ethernet, maybe there's an IPv6 issue with ue(4), 
I hope not.

Anyway, in /etc/rc.conf, your interface lines should look something 
like:

ifconfig_em0_ipv6="inet6 accept_rtadv"

Also, ipv6_defaultrouter must be empty for SLAAC to work.

-- 
Trond.