pfSense does not reply to NS sent by ISP router, ISP does not respond to DHCPv6 request as a result
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@JKnott Everything here is captured in the same way, Wireshark with a port mirror.
Here is the order:
duplicate address detection
solicit XID (x5)
neighbor solicit from 2a00:7660::248 and 2a00:7660::249This pattern repeats, as pfSense is waiting for a reply to the solicit XID and ISP routers are waiting for a reply to the neighbor solicits before sending a reply to the XID.
Interestingly I also tried setting up a pure FreeBSD 12.2 machine, just to see if that would reply to the NS, but no dice, so it seems that the problem lies somewhere below pfSense.
Here is a capture of that NS-no-response.pcapng
As you can see, same pattern, the ISP routers refuses to do anything before they get a reply to the NS they are sending out, while FreeBSD refuses to reply.
I know that everything will work, if I can just get pfSense/FreeBSD to reply to that NS, as I have experimented with Linux, which replies to the NS after which everything runs smoothly:
10 5.677136 2a00:7660::248 ff02::1:ffc9:11ee ICMPv6 86 Neighbor Solicitation for fe80::541e:337d:38c9:11ee from e6:5d:37:84:53:17 11 5.677141 fe80::541e:337d:38c9:11ee 2a00:7660::248 ICMPv6 86 Neighbor Advertisement fe80::541e:337d:38c9:11ee (sol, ovr) is at ac:16:2d:94:bb:d3 12 5.677527 2a00:7660::249 ff02::1:ffc9:11ee ICMPv6 86 Neighbor Solicitation for fe80::541e:337d:38c9:11ee from fe:33:42:10:c8:6b 13 5.677724 fe80::541e:337d:38c9:11ee 2a00:7660::249 ICMPv6 86 Neighbor Advertisement fe80::541e:337d:38c9:11ee (sol, ovr) is at ac:16:2d:94:bb:d3 14 5.678332 fe80::e65d:37ff:fe84:5317 fe80::541e:337d:38c9:11ee ICMPv6 78 Router Advertisement from e6:5d:37:84:53:17 15 5.678687 fe80::fe33:42ff:fe10:c86b fe80::541e:337d:38c9:11ee ICMPv6 78 Router Advertisement from fe:33:42:10:c8:6b -
@cnrd said in pfSense does not reply to NS sent by ISP router, ISP does not respond to DHCPv6 request as a result:
This pattern repeats, as pfSense is waiting for a reply to the solicit XID and ISP routers are waiting for a reply to the neighbor solicits before sending a reply to the XID.
pfsense startup.pcapng
Interestingly I also tried setting up a pure FreeBSD 12.2 machine, just to see if that would reply to the NS, but no dice, so it seems that the problem lies somewhere below pfSense.It looks to me like the problem is with the ISP, given the lack of responses. I assume your modem is in bridge mode, not gateway.
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@JKnott I'm using a fiber modem, so there is no other routers in between.
I don't think it's a problem on my ISP's side, as everything works as soon as the client on my side replies to the NS send by the ISP router.
Booting into another OS that will reply to the ISP router NS and then back into pfSense results in pfSense getting both an IPv6 and a PD. The problem is that this only works for a couple of hours until the ISP router's cache run out and pfSense does not reply to the new NS send out at that time.
I'm starting to suspect that this may actually be a bug in the ND implementation of FreeBSD.
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If whatever device is in gateway mode, pfsense will not work properly. Do you get NAT addresses on IPv4? If so, the modem is likely in gateway mode. I don't know what you have, but around here, the phone company provides fibre connections through the exact same device as they use for ADSL. It has connectors for both a phone line and Ethernet. If the customer is on fibre, then the Ethernet port connects to the fibre interface. I have a cable modem and the first thing I did when I got it, was to put it in bridge mode.
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@JKnott there is no router function in the modem I have it is literally a fiber modem. I have a public IPv4 and in other OS'es than pfSense I get an IPv6-PD/NA.
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Well, I don't know what else to tell you. It works fine for me and many others. But when I look at your capture and see all those unanswered solicitations I don't think the problem is with pfsense. You have to find out why the ISP is not responding to them. I see 14 lines of them and not a single response. While I don't see a router solicitation, I do see the solicit XID to a multicast address. Why no response to that?
What is your WAN config? Mine says DHCP6.
Also, in your first post you said "When pfSense sends out a DHCPv6 request, my ISP sends out an NS, which pfSense never replies to <-- This seems to be what causes the problem.", but I don't see that in the packet capture.
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@JKnott yeah I don't really know what else there is to try either.
WAN is set to DHCPv6.
The NS from the ISP comes right after the XID in the latest capture.
All I can say is that in other OS'es it's working because they reply to that NS.
I don't really know what to ask my ISP about, as I haven't found any documentation/RFC showing that what they are doing is out of spec.
Anyways thanks for trying :-) as the same thing is happening upstream in FreeBSD, I'll probably try over there.
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You might also mention who your ISP is. Someone else might have experience with them.
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@JKnott My ISP is Gigabit.dk
As I wanted to test my theory that it would not reply to global addresses, I hand-crafted two different packages using scapy.
The only difference between these two packages is the fact that one uses a global IP as the src, while the other uses a local-link address.
I'm going to open a bug-report with those two minimal examples.
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Not sure this is a bug.
How is an IPv6 host supposed to source a packet to a GUA unicast address from a link-local address? Link-local is link-local, not GUA. The host has no idea that the GUA address is on the next hop. If it is not, the router receiving the packet should not forward the packet if it is sourced from the link-local address. The host cannot source the packet from a GUA address because DHCP6 has not occurred yet (It doesn't have one).
I tried to find something hard in the RFCs that states this but came up empty.
macos to pfSense: Ping in the link-local context works: $ ping6 -S fe80::183d:38c9:7896:973b%vlan0 fe80::1:1%vlan0 PING6(56=40+8+8 bytes) fe80::183d:38c9:7896:973b%vlan0 --> fe80::1:1%vlan0 16 bytes from fe80::1:1%vlan0, icmp_seq=0 hlim=64 time=0.168 ms 16 bytes from fe80::1:1%vlan0, icmp_seq=1 hlim=64 time=0.151 ms 16 bytes from fe80::1:1%vlan0, icmp_seq=2 hlim=64 time=0.142 ms 16 bytes from fe80::1:1%vlan0, icmp_seq=3 hlim=64 time=0.225 ms ^C --- fe80::1:1%vlan0 ping6 statistics --- 4 packets transmitted, 4 packets received, 0.0% packet loss round-trip min/avg/max/std-dev = 0.142/0.171/0.225/0.032 ms Ping link-local to GUA fails: $ ping6 -S fe80::183d:38c9:7896:973b%vlan0 2001:470:beef:1::1 PING6(56=40+8+8 bytes) fe80::183d:38c9:7896:973b%vlan0 --> 2001:470:beef:1::1 ^C --- 2001:470:beef:1::1 ping6 statistics --- 5 packets transmitted, 0 packets received, 100.0% packet loss Ping GUA to GUA works: $ ping6 -S 2001:470:beef:1:8444:5b18:abab:96f0 2001:470:beef:1::1 PING6(56=40+8+8 bytes) 2001:470:beef:1:8444:5b18:abab:96f0 --> 2001:470:beef:1::1 16 bytes from 2001:470:beef:1::1, icmp_seq=0 hlim=64 time=0.201 ms 16 bytes from 2001:470:beef:1::1, icmp_seq=1 hlim=64 time=0.203 ms 16 bytes from 2001:470:beef:1::1, icmp_seq=2 hlim=64 time=0.211 ms ^C --- 2001:470:beef:1::1 ping6 statistics --- 3 packets transmitted, 3 packets received, 0.0% packet loss round-trip min/avg/max/std-dev = 0.201/0.205/0.211/0.004 msIs this the same ISP that expected its customers to periodically send a Router Solicitation even though the RFCs explicitly state one MUST NOT do that except in certain instances like an interface reconfiguration, link down/up, etc?
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@Derelict No they are sending out RA as expected, they had a problem where the RA packages was thrown away, but that was fixed by their HW vendor.
I have been speaking to one of their internal IT guys, they have been very helpful and tried changing the config of their routers, such that it would send the NS using a link local address, that fixed this problem, but unfortunately broke the DHCP hand-out.
I tried to find something hard in the RFCs that states this but came up empty.
I know that it sounds wierd, but as Linux supports it and there is nothing in the RFC stating that it's wrong, I can't really see why it shouldn't be okay. I can see your argument, it does make sense, but if it's not disallowed by the RFC, then someone (in this case the HW vendor of my ISP) chooses to do it.
How is an IPv6 host supposed to source a packet to a GUA unicast address from a link-local address?
Here is how debian does it:
2 0.000005 fe80::541e:337d:38c9:11ee 2a00:7660::248 ICMPv6 86 Neighbor Advertisement fe80::541e:337d:38c9:11ee (sol, ovr) is at ac:16:2d:94:bb:d3It is the responsibility of the receiver (router) to not forward that outside of the link local.
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@cnrd said in pfSense does not reply to NS sent by ISP router, ISP does not respond to DHCPv6 request as a result:
I have been speaking to one of their internal IT guys, they have been very helpful and tried changing the config of their routers, such that it would send the NS using a link local address, that fixed this problem, but unfortunately broke the DHCP hand-out.
One thing I've noticed is the ISPs tech are not fully up to speed on IPv6. A couple of years ago, I had a problem with my ISP where I could not reach the Internet with IPv6. After testing on my own, I had determined the problem was not on my network. I called 2nd level support (I don't waste my time with 1st) and had to talk him through how DHCPv6-PD works and how the WAN address is not used for routing. He was then able to verify the problem was elsewhere. But when he tried to get the network guys to work on it, they refused because I had my own router, even though a neighbour had the same problem and he was only using the ISP's router. I had even determined the failing system, by host name, at the head end, by examining the DHCPv6-PD sequence with Wireshark. I then had a senior tech come to my home and again explained how things worked. He tried, with his own computer and modem, and it failed for him too. He then took his computer to the office and tried with 4 different systems and only the one I was connected to failed. The network guys finally accepted the problem and resolved it.
I was able to work my way through this because I have decades of experience with telecom, computers and networks. An average customer wouldn't have a hope.
Bottom line, you can't always count on the ISP's techs to fully understand what they're doing.
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@JKnott can't really reveal who I talked to, but trust me, not an average tech.
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@cnrd I have been following this thread with great interest.
I use the same ISP, and have exactly the same issue, in that the NS coming in is being ignored, and the DHCP6 requests in turn keep being ignored by Gigabit.
Funny thing is that this worked me for several years, until it stopped, around the time there was a large outage in connection with some infra upgrades being done at the time. It's possibly related with those infrastructure changes.
Did you have any luck with support? I have a support case registered a couple of weeks ago for the same thing, and I think I will point them to this thread, unless you found a workaround on the BSD/pfSense side.
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@abw Unfortunately not. Yeah it seems like the upgrade of hardware caused the problem.
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@cnrd Just had a breakthrough, and now have the full /48 running with DHCPv6 on pfSense.
My problem was due to having a user defined MAC address on the WAN interface.I've always had a user defined MAC address configured on the WAN interface (Interfaces > WAN > MAC Address), so as to ensure my static IPv4 address over several hardware changes.
After reading everything you had tried, I wanted to test the theory that this user-defined address might have an impact on pfSense/FreeBSDs ability to respond to the NS.
It seems that this is the root cause of my issue, because when removed it, and let it default to the hardware MAC, DHCPv6 and the PD came up immediately.
Of course I no longer had an IPv4 address, but I just called up the ISP and they changed the static DHCP4 allocation to my new MAC for me on the spot.Now, with the hardware MAC in use, the NS works perfectly.
So my current root cause theory is that, whatever mechanism pfSense uses to "spoof" the MAC address, does not appear to propagate to the part of FreeBSD that is responsible for NS responses. Only a theory though.
I really hope this helps you.
By the way, I only have the following checked in the WAN configuration now:
Prefix Delegation Size: /48
Send IPv6 Prefix Hint: SETReboot pfSense, and that's it.
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@abw huh wierd, any chance you can try to capture the NS/NA handshake? Maybe they have a different router setup where you are connected.
If you cannot capture the handshake, could you try to figure out what IP the router is presenting in packages?
Thanks!
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@abw said in pfSense does not reply to NS sent by ISP router, ISP does not respond to DHCPv6 request as a result:
So my current root cause theory is that, whatever mechanism pfSense uses to "spoof" the MAC address, does not appear to propagate to the part of FreeBSD that is responsible for NS responses. Only a theory though.
There's a bit in the MAC to designate a universal or locally assigned address. Perhaps that's what's causing the problem. You should be able to check that with a packet capture.
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@JKnott Thanks for the idea!
My old statically coded MAC address OUI was bc:05:43 which came from a FritzBox I had for many years.
The new OUI, which works, is 00:1f:29, which is registered to HP.Both have the second LSB of the first octet set to zero (UAA), so I guess that's not it.
In my working configuration I had also set the tunable net.inet6.icmp6.nd6_onlink_ns_rfc4861 to 1, but I have not yet retested with it set to zero to determine if it's actually necessary.
I still need to experiment a little more to isolate the fix.
