I'm running Ubuntu 16.04 behind a router. I can get IPv6 on the router working, but it fails on the client. If anyone has any input on how I can resolve that, I'd appreciate it.
I can use either SLAAC (radvdump output, below) or DHCPv6 to get an IP from the ISP, resulting in an IP based on the MAC of the router's WAN interface, plus a link-local. ip -6 addr on the router shows:
inet6 2607:X:X:X:Y:yff:fey:Y/64 scope global dynamic
Then, I can set the router's LAN interface to static: 2607:X:X:X::/64 and use the routers's stateless or stateful DHCP server to get addresses for the client (first address only present when using the stateful server):
inet6 2607:X:X:X::x/128 scope global dynamic
inet6 2607:X:X:X:Y':Y':Y':Y'/64 scope global temporary dynamic
inet6 2607:X:X:X:Z:Z:Z:Z/64 scope global mngtmpaddr noprefixroute dynamic
ip -6 route on the client (first route only present when using the stateful server and fe80::Y:yff:fey:Y is the link-local ip of the router's LAN interface)
2607:X:X:X::x dev enp0s25 proto kernel metric 256 expires 86292sec pref medium
2607:X:X:X::/64 via fe80::Y:yff:fey:Y dev enp0s25 proto ra metric 100 pref medium
2607:X:X:X::/64 dev enp0s25 proto kernel metric 256 expires 7090sec pref medium
fe80::/64 dev enp0s25 proto kernel metric 256 pref medium
default via fe80::Y:yff:fey:Y dev enp0s25 proto static metric 100 pref medium
When the router is set to use DHCP with the ISP, I can also try to dispense with the static setting for the router's LAN interface, by using prefix delegation; but then whether I use stateful or stateless DHCP with the client, I only get a link-local address. This seems odd as the prefix/netmask are included in the ISP's router advertisement (below).
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# radvdump [run on the router]
interface ath0
{
AdvSendAdvert on;
# Note: {Min,Max}RtrAdvInterval cannot be obtained with radvdump
AdvManagedFlag off;
AdvOtherConfigFlag on;
AdvReachableTime 0;
AdvRetransTimer 0;
AdvCurHopLimit 64;
AdvDefaultLifetime 1800;
AdvHomeAgentFlag off;
AdvDefaultPreference medium;
AdvSourceLLAddress on;
RDNSS 2607:X:X:X::53
{
AdvRDNSSPreference 0;
AdvRDNSSOpen off;
AdvRDNSSLifetime 1800;
}; # End of RDNSS definition
prefix 2607:X:Y:Y::/64
{
AdvValidLifetime 2592000;
AdvPreferredLifetime 604800;
AdvOnLink on;
AdvAutonomous on;
AdvRouterAddr off;
}; # End of prefix definition
}; # End of interface definition
#
# radvd configuration generated by radvdump 1.2
# based on Router Advertisement from fe80::Z:Z:Z:Z
# received by interface ath0
/etc/network/interfaces is unchanged from the ubuntu install:
auto lo
iface lo inet loopback
I also note here the output of sysctl. This answer indicates I may need to change some of these, but others indicate that changes should be in the interfaces file and/or Network Manager, and that these don't play well with sysctl. It's the enp0s25 interface that connects to the LAN:
$ sudo sysctl -a | grep accept_ra
net.ipv6.conf.all.accept_ra = 1
net.ipv6.conf.all.accept_ra_defrtr = 1
net.ipv6.conf.all.accept_ra_from_local = 0
net.ipv6.conf.all.accept_ra_min_hop_limit = 1
net.ipv6.conf.all.accept_ra_mtu = 1
net.ipv6.conf.all.accept_ra_pinfo = 1
net.ipv6.conf.all.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.all.accept_ra_rtr_pref = 1
net.ipv6.conf.default.accept_ra = 1
net.ipv6.conf.default.accept_ra_defrtr = 1
net.ipv6.conf.default.accept_ra_from_local = 0
net.ipv6.conf.default.accept_ra_min_hop_limit = 1
net.ipv6.conf.default.accept_ra_mtu = 1
net.ipv6.conf.default.accept_ra_pinfo = 1
net.ipv6.conf.default.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.default.accept_ra_rtr_pref = 1
net.ipv6.conf.enp0s25.accept_ra = 1
net.ipv6.conf.enp0s25.accept_ra_defrtr = 0
net.ipv6.conf.enp0s25.accept_ra_from_local = 0
net.ipv6.conf.enp0s25.accept_ra_min_hop_limit = 1
net.ipv6.conf.enp0s25.accept_ra_mtu = 1
net.ipv6.conf.enp0s25.accept_ra_pinfo = 0
net.ipv6.conf.enp0s25.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.enp0s25.accept_ra_rtr_pref = 0
net.ipv6.conf.lo.accept_ra = 1
net.ipv6.conf.lo.accept_ra_defrtr = 1
net.ipv6.conf.lo.accept_ra_from_local = 0
net.ipv6.conf.lo.accept_ra_min_hop_limit = 1
net.ipv6.conf.lo.accept_ra_mtu = 1
net.ipv6.conf.lo.accept_ra_pinfo = 1
net.ipv6.conf.lo.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.lo.accept_ra_rtr_pref = 1
net.ipv6.conf.virbr0.accept_ra = 0
net.ipv6.conf.virbr0.accept_ra_defrtr = 1
net.ipv6.conf.virbr0.accept_ra_from_local = 0
net.ipv6.conf.virbr0.accept_ra_min_hop_limit = 1
net.ipv6.conf.virbr0.accept_ra_mtu = 1
net.ipv6.conf.virbr0.accept_ra_pinfo = 1
net.ipv6.conf.virbr0.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.virbr0.accept_ra_rtr_pref = 1
net.ipv6.conf.virbr0-nic.accept_ra = 1
net.ipv6.conf.virbr0-nic.accept_ra_defrtr = 1
net.ipv6.conf.virbr0-nic.accept_ra_from_local = 0
net.ipv6.conf.virbr0-nic.accept_ra_min_hop_limit = 1
net.ipv6.conf.virbr0-nic.accept_ra_mtu = 1
net.ipv6.conf.virbr0-nic.accept_ra_pinfo = 1
net.ipv6.conf.virbr0-nic.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.virbr0-nic.accept_ra_rtr_pref = 1
net.ipv6.conf.wlp3s0.accept_ra = 0
net.ipv6.conf.wlp3s0.accept_ra_defrtr = 0
net.ipv6.conf.wlp3s0.accept_ra_from_local = 0
net.ipv6.conf.wlp3s0.accept_ra_min_hop_limit = 1
net.ipv6.conf.wlp3s0.accept_ra_mtu = 1
net.ipv6.conf.wlp3s0.accept_ra_pinfo = 0
net.ipv6.conf.wlp3s0.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.wlp3s0.accept_ra_rtr_pref = 0
