4

My hosting provider supplied me with the following information:

Subnet: 2a02:f99:0:64::/64
Gateway: 2a02:f99:0:64::1

So I did (yes eth3 is the correct interface)

ip addr add 2a02:f99:0:64::2/64 dev eth3
ip -6 route add ::/0 via 2a02:f99:0:64::1 dev eth3

but

$ ip -6 neigh show
2a02:f99:0:64::1 dev eth3 FAILED
$ ping6 google.com
PING google.com(ams16s30-in-x0e.1e100.net) 56 data bytes
From 2a02:f99:0:64::2 icmp_seq=1 Destination unreachable: Address unreachable
...

I also tried

ip -6 route del ::/0 via 2a02:f99:0:64::1 dev eth3
ip -6 route add ::/0 via fe80::1 dev eth3

but that didn't change anything, still can't ping in or out.

Where did I go wrong? How do I get IPv6 running?


Update 2017-07-07:

Hosting provider insists infrastructure is fine.

Another machine with access to the same subnet can bind the address and establish an IPv6 connection via what I think is Router Advertisement (RA), as only fe80::20a:8bff:fe98:3400 as a gateway works and the provider specified gateway address doesn't.

The machine this post is about, however, is still out of luck finding any neighbors at all. Enabling RA also seems to have no effect whatsoever.

Running IPv6 accross the two machine's crossover connection (on their secondary NICs) worked right away, so IPv6 should basically be available to both of them (all pastes from the problematic machine):

PING fe80::62eb:69ff:fed2:a122%eth2(fe80::62eb:69ff:fed2:a122) 56 data bytes
64 bytes from fe80::62eb:69ff:fed2:a122: icmp_seq=1 ttl=64 time=0.224 ms
64 bytes from fe80::62eb:69ff:fed2:a122: icmp_seq=2 ttl=64 time=0.171 ms
--- fe80::62eb:69ff:fed2:a122%eth2 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 999ms

PING fd00:32::3(fd00:32::3) 56 data bytes
64 bytes from fd00:32::3: icmp_seq=1 ttl=64 time=0.286 ms
64 bytes from fd00:32::3: icmp_seq=2 ttl=64 time=0.168 ms
--- fd00:32::3 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms

IP configuration looks like:

2: eth3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc htb state UP qlen 1000
    link/ether f0:1f:af:df:c8:7b brd ff:ff:ff:ff:ff:ff
    inet 85.XX.XX.186/30 brd 85.XX.XX.187 scope global eth3
    inet6 2a02:f99:0:64::2/64 scope global 
       valid_lft forever preferred_lft forever
    inet6 fe80::f21f:afff:fedf:c87b/64 scope link 
       valid_lft forever preferred_lft forever

2a02:f99:0:64::/64 dev eth3  proto kernel  metric 256 
fd00:32::/32 dev eth2  proto kernel  metric 256 
fe80::/64 dev eth2  proto kernel  metric 256 
fe80::/64 dev eth3-ifb  proto kernel  metric 256 
fe80::/64 dev eth3  proto kernel  metric 256 
default via 2a02:f99:0:64::1 dev eth3  metric 1024 

Neighbor discovery only finds the interface's link-local address:

PING ff02::1%eth3(ff02::1) 56 data bytes
64 bytes from fe80::f21f:afff:fedf:c87b: icmp_seq=1 ttl=64 time=0.055 ms
64 bytes from fe80::f21f:afff:fedf:c87b: icmp_seq=2 ttl=64 time=0.076 ms
64 bytes from fe80::f21f:afff:fedf:c87b: icmp_seq=3 ttl=64 time=0.060 ms
--- ff02::1%eth3 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 1998ms

Trying to ping the gateway also results in:

PING 2a02:f99:0:64::1(2a02:f99:0:64::1) from 2a02:f99:0:64::2 eth3: 56 data bytes
From 2a02:f99:0:64::2 icmp_seq=1 Destination unreachable: Address unreachable
From 2a02:f99:0:64::2 icmp_seq=2 Destination unreachable: Address unreachable
From 2a02:f99:0:64::2 icmp_seq=3 Destination unreachable: Address unreachable
--- 2a02:f99:0:64::1 ping statistics ---
5 packets transmitted, 0 received, +3 errors, 100% packet loss, time 3999ms

Here's what sysctl -A | grep ipv6 spits out (where I can't spot anything wrong either):

net.ipv6.neigh.default.mcast_solicit = 3
net.ipv6.neigh.default.ucast_solicit = 3
net.ipv6.neigh.default.app_solicit = 0
net.ipv6.neigh.default.delay_first_probe_time = 5
net.ipv6.neigh.default.gc_stale_time = 60
net.ipv6.neigh.default.unres_qlen = 3
net.ipv6.neigh.default.proxy_qlen = 64
net.ipv6.neigh.default.anycast_delay = 100
net.ipv6.neigh.default.proxy_delay = 80
net.ipv6.neigh.default.locktime = 0
net.ipv6.neigh.default.retrans_time_ms = 1000
net.ipv6.neigh.default.base_reachable_time_ms = 30000
net.ipv6.neigh.default.gc_interval = 30
net.ipv6.neigh.default.gc_thresh1 = 128
net.ipv6.neigh.default.gc_thresh2 = 512
net.ipv6.neigh.default.gc_thresh3 = 1024
net.ipv6.neigh.lo.mcast_solicit = 3
net.ipv6.neigh.lo.ucast_solicit = 3
net.ipv6.neigh.lo.app_solicit = 0
net.ipv6.neigh.lo.delay_first_probe_time = 5
net.ipv6.neigh.lo.gc_stale_time = 60
net.ipv6.neigh.lo.unres_qlen = 3
net.ipv6.neigh.lo.proxy_qlen = 64
net.ipv6.neigh.lo.anycast_delay = 100
net.ipv6.neigh.lo.proxy_delay = 80
net.ipv6.neigh.lo.locktime = 0
net.ipv6.neigh.lo.retrans_time_ms = 1000
net.ipv6.neigh.lo.base_reachable_time_ms = 30000
net.ipv6.neigh.eth3.mcast_solicit = 3
net.ipv6.neigh.eth3.ucast_solicit = 3
net.ipv6.neigh.eth3.app_solicit = 0
net.ipv6.neigh.eth3.delay_first_probe_time = 5
net.ipv6.neigh.eth3.gc_stale_time = 60
net.ipv6.neigh.eth3.unres_qlen = 3
net.ipv6.neigh.eth3.proxy_qlen = 64
net.ipv6.neigh.eth3.anycast_delay = 100
net.ipv6.neigh.eth3.proxy_delay = 80
net.ipv6.neigh.eth3.locktime = 0
net.ipv6.neigh.eth3.retrans_time_ms = 1000
net.ipv6.neigh.eth3.base_reachable_time_ms = 30000
net.ipv6.neigh.eth2.mcast_solicit = 3
net.ipv6.neigh.eth2.ucast_solicit = 3
net.ipv6.neigh.eth2.app_solicit = 0
net.ipv6.neigh.eth2.delay_first_probe_time = 5
net.ipv6.neigh.eth2.gc_stale_time = 60
net.ipv6.neigh.eth2.unres_qlen = 3
net.ipv6.neigh.eth2.proxy_qlen = 64
net.ipv6.neigh.eth2.anycast_delay = 100
net.ipv6.neigh.eth2.proxy_delay = 80
net.ipv6.neigh.eth2.locktime = 0
net.ipv6.neigh.eth2.retrans_time_ms = 1000
net.ipv6.neigh.eth2.base_reachable_time_ms = 30000
net.ipv6.neigh.eth3-ifb.mcast_solicit = 3
net.ipv6.neigh.eth3-ifb.ucast_solicit = 3
net.ipv6.neigh.eth3-ifb.app_solicit = 0
net.ipv6.neigh.eth3-ifb.delay_first_probe_time = 5
net.ipv6.neigh.eth3-ifb.gc_stale_time = 60
net.ipv6.neigh.eth3-ifb.unres_qlen = 3
net.ipv6.neigh.eth3-ifb.proxy_qlen = 64
net.ipv6.neigh.eth3-ifb.anycast_delay = 100
net.ipv6.neigh.eth3-ifb.proxy_delay = 80
net.ipv6.neigh.eth3-ifb.locktime = 0
net.ipv6.neigh.eth3-ifb.retrans_time_ms = 1000
net.ipv6.neigh.eth3-ifb.base_reachable_time_ms = 30000
net.ipv6.xfrm6_gc_thresh = 2048
net.ipv6.conf.all.forwarding = 0
net.ipv6.conf.all.hop_limit = 64
net.ipv6.conf.all.mtu = 1280
net.ipv6.conf.all.accept_ra = 1
net.ipv6.conf.all.accept_redirects = 1
net.ipv6.conf.all.autoconf = 1
net.ipv6.conf.all.dad_transmits = 1
net.ipv6.conf.all.router_solicitations = 3
net.ipv6.conf.all.router_solicitation_interval = 4
net.ipv6.conf.all.router_solicitation_delay = 1
net.ipv6.conf.all.force_mld_version = 0
net.ipv6.conf.all.use_tempaddr = 0
net.ipv6.conf.all.temp_valid_lft = 604800
net.ipv6.conf.all.temp_prefered_lft = 86400
net.ipv6.conf.all.regen_max_retry = 3
net.ipv6.conf.all.max_desync_factor = 600
net.ipv6.conf.all.max_addresses = 16
net.ipv6.conf.all.accept_ra_defrtr = 1
net.ipv6.conf.all.accept_ra_pinfo = 1
net.ipv6.conf.all.accept_ra_rtr_pref = 1
net.ipv6.conf.all.router_probe_interval = 60
net.ipv6.conf.all.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.all.proxy_ndp = 0
net.ipv6.conf.all.accept_source_route = 0
net.ipv6.conf.all.optimistic_dad = 0
net.ipv6.conf.all.mc_forwarding = 0
net.ipv6.conf.all.disable_ipv6 = 0
net.ipv6.conf.all.accept_dad = 1
net.ipv6.conf.all.force_tllao = 0
net.ipv6.conf.default.forwarding = 0
net.ipv6.conf.default.hop_limit = 64
net.ipv6.conf.default.mtu = 1280
net.ipv6.conf.default.accept_ra = 1
net.ipv6.conf.default.accept_redirects = 1
net.ipv6.conf.default.autoconf = 1
net.ipv6.conf.default.dad_transmits = 1
net.ipv6.conf.default.router_solicitations = 3
net.ipv6.conf.default.router_solicitation_interval = 4
net.ipv6.conf.default.router_solicitation_delay = 1
net.ipv6.conf.default.force_mld_version = 0
net.ipv6.conf.default.use_tempaddr = 0
net.ipv6.conf.default.temp_valid_lft = 604800
net.ipv6.conf.default.temp_prefered_lft = 86400
net.ipv6.conf.default.regen_max_retry = 3
net.ipv6.conf.default.max_desync_factor = 600
net.ipv6.conf.default.max_addresses = 16
net.ipv6.conf.default.accept_ra_defrtr = 1
net.ipv6.conf.default.accept_ra_pinfo = 1
net.ipv6.conf.default.accept_ra_rtr_pref = 1
net.ipv6.conf.default.router_probe_interval = 60
net.ipv6.conf.default.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.default.proxy_ndp = 0
net.ipv6.conf.default.accept_source_route = 0
net.ipv6.conf.default.optimistic_dad = 0
net.ipv6.conf.default.mc_forwarding = 0
net.ipv6.conf.default.disable_ipv6 = 0
net.ipv6.conf.default.accept_dad = 1
net.ipv6.conf.default.force_tllao = 0
net.ipv6.conf.lo.forwarding = 0
net.ipv6.conf.lo.hop_limit = 64
net.ipv6.conf.lo.mtu = 16436
net.ipv6.conf.lo.accept_ra = 1
net.ipv6.conf.lo.accept_redirects = 1
net.ipv6.conf.lo.autoconf = 1
net.ipv6.conf.lo.dad_transmits = 1
net.ipv6.conf.lo.router_solicitations = 3
net.ipv6.conf.lo.router_solicitation_interval = 4
net.ipv6.conf.lo.router_solicitation_delay = 1
net.ipv6.conf.lo.force_mld_version = 0
net.ipv6.conf.lo.use_tempaddr = -1
net.ipv6.conf.lo.temp_valid_lft = 604800
net.ipv6.conf.lo.temp_prefered_lft = 86400
net.ipv6.conf.lo.regen_max_retry = 3
net.ipv6.conf.lo.max_desync_factor = 600
net.ipv6.conf.lo.max_addresses = 16
net.ipv6.conf.lo.accept_ra_defrtr = 1
net.ipv6.conf.lo.accept_ra_pinfo = 1
net.ipv6.conf.lo.accept_ra_rtr_pref = 1
net.ipv6.conf.lo.router_probe_interval = 60
net.ipv6.conf.lo.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.lo.proxy_ndp = 0
net.ipv6.conf.lo.accept_source_route = 0
net.ipv6.conf.lo.optimistic_dad = 0
net.ipv6.conf.lo.mc_forwarding = 0
net.ipv6.conf.lo.disable_ipv6 = 0
net.ipv6.conf.lo.accept_dad = -1
net.ipv6.conf.lo.force_tllao = 0
net.ipv6.conf.eth3.forwarding = 0
net.ipv6.conf.eth3.hop_limit = 64
net.ipv6.conf.eth3.mtu = 1500
net.ipv6.conf.eth3.accept_ra = 1
net.ipv6.conf.eth3.accept_redirects = 1
net.ipv6.conf.eth3.autoconf = 0
net.ipv6.conf.eth3.dad_transmits = 1
net.ipv6.conf.eth3.router_solicitations = 3
net.ipv6.conf.eth3.router_solicitation_interval = 4
net.ipv6.conf.eth3.router_solicitation_delay = 1
net.ipv6.conf.eth3.force_mld_version = 0
net.ipv6.conf.eth3.use_tempaddr = 1
net.ipv6.conf.eth3.temp_valid_lft = 604800
net.ipv6.conf.eth3.temp_prefered_lft = 86400
net.ipv6.conf.eth3.regen_max_retry = 3
net.ipv6.conf.eth3.max_desync_factor = 600
net.ipv6.conf.eth3.max_addresses = 16
net.ipv6.conf.eth3.accept_ra_defrtr = 1
net.ipv6.conf.eth3.accept_ra_pinfo = 1
net.ipv6.conf.eth3.accept_ra_rtr_pref = 1
net.ipv6.conf.eth3.router_probe_interval = 60
net.ipv6.conf.eth3.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.eth3.proxy_ndp = 0
net.ipv6.conf.eth3.accept_source_route = 0
net.ipv6.conf.eth3.optimistic_dad = 0
net.ipv6.conf.eth3.mc_forwarding = 0
net.ipv6.conf.eth3.disable_ipv6 = 0
net.ipv6.conf.eth3.accept_dad = 1
net.ipv6.conf.eth3.force_tllao = 0
net.ipv6.conf.eth2.forwarding = 0
net.ipv6.conf.eth2.hop_limit = 64
net.ipv6.conf.eth2.mtu = 1500
net.ipv6.conf.eth2.accept_ra = 1
net.ipv6.conf.eth2.accept_redirects = 1
net.ipv6.conf.eth2.autoconf = 1
net.ipv6.conf.eth2.dad_transmits = 1
net.ipv6.conf.eth2.router_solicitations = 3
net.ipv6.conf.eth2.router_solicitation_interval = 4
net.ipv6.conf.eth2.router_solicitation_delay = 1
net.ipv6.conf.eth2.force_mld_version = 0
net.ipv6.conf.eth2.use_tempaddr = 0
net.ipv6.conf.eth2.temp_valid_lft = 604800
net.ipv6.conf.eth2.temp_prefered_lft = 86400
net.ipv6.conf.eth2.regen_max_retry = 3
net.ipv6.conf.eth2.max_desync_factor = 600
net.ipv6.conf.eth2.max_addresses = 16
net.ipv6.conf.eth2.accept_ra_defrtr = 1
net.ipv6.conf.eth2.accept_ra_pinfo = 1
net.ipv6.conf.eth2.accept_ra_rtr_pref = 1
net.ipv6.conf.eth2.router_probe_interval = 60
net.ipv6.conf.eth2.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.eth2.proxy_ndp = 0
net.ipv6.conf.eth2.accept_source_route = 0
net.ipv6.conf.eth2.optimistic_dad = 0
net.ipv6.conf.eth2.mc_forwarding = 0
net.ipv6.conf.eth2.disable_ipv6 = 0
net.ipv6.conf.eth2.accept_dad = 1
net.ipv6.conf.eth2.force_tllao = 0
net.ipv6.conf.eth3-ifb.forwarding = 0
net.ipv6.conf.eth3-ifb.hop_limit = 64
net.ipv6.conf.eth3-ifb.mtu = 1500
net.ipv6.conf.eth3-ifb.accept_ra = 1
net.ipv6.conf.eth3-ifb.accept_redirects = 1
net.ipv6.conf.eth3-ifb.autoconf = 1
net.ipv6.conf.eth3-ifb.dad_transmits = 1
net.ipv6.conf.eth3-ifb.router_solicitations = 3
net.ipv6.conf.eth3-ifb.router_solicitation_interval = 4
net.ipv6.conf.eth3-ifb.router_solicitation_delay = 1
net.ipv6.conf.eth3-ifb.force_mld_version = 0
net.ipv6.conf.eth3-ifb.use_tempaddr = 0
net.ipv6.conf.eth3-ifb.temp_valid_lft = 604800
net.ipv6.conf.eth3-ifb.temp_prefered_lft = 86400
net.ipv6.conf.eth3-ifb.regen_max_retry = 3
net.ipv6.conf.eth3-ifb.max_desync_factor = 600
net.ipv6.conf.eth3-ifb.max_addresses = 16
net.ipv6.conf.eth3-ifb.accept_ra_defrtr = 1
net.ipv6.conf.eth3-ifb.accept_ra_pinfo = 1
net.ipv6.conf.eth3-ifb.accept_ra_rtr_pref = 1
net.ipv6.conf.eth3-ifb.router_probe_interval = 60
net.ipv6.conf.eth3-ifb.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.eth3-ifb.proxy_ndp = 0
net.ipv6.conf.eth3-ifb.accept_source_route = 0
net.ipv6.conf.eth3-ifb.optimistic_dad = 0
net.ipv6.conf.eth3-ifb.mc_forwarding = 0
net.ipv6.conf.eth3-ifb.disable_ipv6 = 0
net.ipv6.conf.eth3-ifb.accept_dad = -1
net.ipv6.conf.eth3-ifb.force_tllao = 0
net.ipv6.ip6frag_high_thresh = 262144
net.ipv6.ip6frag_low_thresh = 196608
net.ipv6.ip6frag_time = 60
net.ipv6.route.gc_thresh = 1024
net.ipv6.route.max_size = 4096
net.ipv6.route.gc_min_interval = 0
net.ipv6.route.gc_timeout = 60
net.ipv6.route.gc_interval = 30
net.ipv6.route.gc_elasticity = 9
net.ipv6.route.mtu_expires = 600
net.ipv6.route.min_adv_mss = 1220
net.ipv6.route.gc_min_interval_ms = 500
net.ipv6.icmp.ratelimit = 1000
net.ipv6.bindv6only = 0
net.ipv6.ip6frag_secret_interval = 600
net.ipv6.mld_max_msf = 64

Update 2017-07-07 #2:

Provider says both machines are hooked into the same switch. Meaning this has to be a configuration issue.


Update 2017-07-08:

I have upgraded the kernel from 3.4 to 3.16 and the Intel igb NIC driver to the latest package from their website. However, to no avail, observed behaviour didn't change at all.

4

The commands you typed at first look entirely correct given the quoted information from the provider. This leaves us with a few possible guesses as to what might be the problem.

  • The provider gave you incorrect information.
  • The correct interface to use is actually not eth3 but something else.
  • There is a severely misconfigured firewall on the path from your machine to the gateway.
  • The communication is not supposed to be using IPv6 over Ethernet but rather some other protocol, which might be IPv6 over PPP over Ethernet.

A whois lookup will reveal that the IP address you are using is part of 2a00::/12 allocated to RIPE but has not yet been allocated to any ISP. So my guess is that the provider mistyped the IP address in the information you received.

A few additional notes which may or may not be of interest. Your route command could be abbreviated to:

ip -6 route add ::/0 via 2a02:f99:0:64::1

It is redundant to specify dev eth3 here because you already have a route indicating that 2a02:f99:0:64::1

I have seen at least one provider use fe80::1 as gateway address. Given that the provider told you to use 2a02:f99:0:64::1 as gateway address it was not supposed to work, but it was still a sensible attempt at figuring out what was wrong.

A couple of other things you can do to attempt finding out what is going on is to look at a packet capture, for example by typing:

tcpdump -ni eth3 ip6 -s0

And you can try to look for all IPv6 nodes on the segment with:

ping6 ff02::1%eth3

But my best advice is to ask the provider for correct information mentioning that 2a02:f99::/32 is unallocated.

  • You could also, try to let it figure out what it should be from the RAs. – Ron Maupin Jul 5 '17 at 20:31
  • I wasn't entirely truthful about the particular addresses for privacy reasons, which shouldn't have any influence on the technicalities. Trying to ping out results in 2a02:f99:0:64::2 > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has 2a02:f99:0:64::1, length 32 in tcpdump, nothing else. – Cobra_Fast Jul 5 '17 at 20:40
  • Pinging ff02::1%eth3 only ever returns the interface's link-local address. I shot an email over to the hosting provider, I'll see what comes of that. – Cobra_Fast Jul 5 '17 at 20:44
  • @Cobra_Fast That can mean one of two things. Either there is nothing else connected to that segment speaking IPv6, or there is a misconfigured firewall in the mix. – kasperd Jul 5 '17 at 21:29
  • @RonMaupin That is worth a try. If any RAs are being sent they should show up in the output from the tcpdump command I suggested. It isn't guaranteed that there will be any RAs though. A host with a static IP configuration can access the network without receiving any RAs, so it is possible the provider configured their router to not send any. – kasperd Jul 5 '17 at 21:53
1

After a week of back and forth with the hosting provider (and countless hours wasted on trying all sorts of things) it turns out that it was a provider/infrastructure problem after all.

After having them plug the servers into a different router everything works fine.

I guess the lesson to be learned here is that providers are not always right when they tell you it's a machine configuration problem.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.