IPv6 traceroute not showing first hop (pfSense)

[JKnott]

I am trying to resolve a problem which I believe is caused by my ISP. In the process of testing, I'm running traceroute to www.yahoo.com. On IPv4, I see pfSense as the first hop. However, on IPv6, I only get an asterisk, which indicates no response from the router. Is this default on pfSense? Can it be fixed?

[JKnott]

I just checked with Wireshark and don't even see a time exceeded message from pfSense on IPv6, but I do on IPv4. Is pfSense discarding IPv6 traceroute? On IPv4, I see both the UDP packet going out and ICMP timeout coming back, but on IPv6, I only see the UDP packet going out, without even an single timeout packet coming back.

[johnpoz]

Your going to have to give us more to work with here... I see pfsense as my first hop in a ipv6 trace.. Nothing special here..

That was from windows, here is from linux on a different ipv6 vlan even

Windows normally does a trace via icmp, while linux udp.

[JKnott]

$ traceroute -6 ipv6.google.com
traceroute to ipv6.google.com (2607:f8b0:400b:808::200e), 30 hops max, 80 byte packets
1 * * *
2 * * *
3 * * *
4 * * *
5 * * *
6 * * *
7 * * *
8 * * *
9 * * *

As you can see, no response, not even from pfSense.

[johnpoz]

Well you got something else going on then.. What are you rules... You doing that stupid ULA shit you love?

[JKnott]

@johnpoz said in IPv6 traceroute not showing first hop (pfSense):

You doing that stupid ULA shit you love?

The packets show global addresses, not ULA. They are received at pfSense, as shown in Packet Capture. They are also leaving pfSense and out to the Internet, as shown with Wireshark, between pfSense computer and modem. I'm just not getting any response from pfSense.

[johnpoz]

what packet capture? I don't see any capture..

[JKnott]

Here's the file. However, I was just mentioning that valid addresses were shown in the captures.
0_1547757089735_packetcapture.pcapng

Curious, this site wouldn't accept the Packet Capture .cap file. I had to use Wireshark to save as .pcapng.

[johnpoz]

I have a meeting I have to run to, take a look see later - do a sniff my own trace, etc. And compare. Again what are you rules? Are you bridging? Your also a big fan of that ;)

[JKnott]

@johnpoz said in IPv6 traceroute not showing first hop (pfSense):

Are you bridging? Your also a big fan of that ;)

The modem is in bridge mode. It's the only way to use a /56 prefix.

[Pippin]

@jknott said in IPv6 traceroute not showing first hop (pfSense):

Curious, this site wouldn't accept the Packet Capture .cap file. I had to use Wireshark to save as .pcapng.

Yeah, I found the same, just renamed it to .*pcap
https://forum.netgate.com/topic/138124/posting-to-a-forum-issue/8

[johnpoz]

What do you mean your modem is in bridge mode? So your gateway is NOT pfsense?

001700 ARRIS Group, Inc.

From your cap that is where your sending the UDP traffic with a TTL of 1, I assume that is your "modem" and not pfsense... So if that is the case why would you think pfsense should answer back as your first hop?

Trace being sent to ipv6.google.com - the mac is pfsense, not my cable modem..

And you notice pfsense sends back answer since the TTL has expired..

[JKnott]

@johnpoz said in IPv6 traceroute not showing first hop (pfSense):

I have a meeting I have to run to, take a look see later

WOW!! That was a long meeting!!!

@johnpoz said in IPv6 traceroute not showing first hop (pfSense):

What do you mean your modem is in bridge mode? So your gateway is NOT pfsense?

Traceroute was run on a computer behind my firewall/router, so pfSense is the first hop

001700 ARRIS Group, Inc.

From your cap that is where your sending the UDP traffic with a TTL of 1, I assume that is your "modem" and not pfsense... So if that is the case why would you think pfsense should answer back as your first hop?

As I mentioned above, it is the first hop. The modem is in bridge mode, so it should be transparent. The capture is done on a computer that's behind pfSense.

Trace being sent to ipv6.google.com - the mac is pfsense, not my cable modem..

<image removed>

And you notice pfsense sends back answer since the TTL has expired..

That's the whole issue. I'm not getting a response from pfSense on IPv6, though I do on IPv4.

BTW, what led to this issue is a problem I have with my ISP. I noticed I was having some performance issues and found IPv6 was not working from my local network. For example pinging & traceroute to Google or Yahoo, with IPv6 failed. However, I could do both from pfSense. In addition, host lookup on the host name for my pfSense firewall shows two different IPv6 addresses, with the last segment of the prefix differing, as well as the entire 64 bit suffix. This leads me to believe there's a routing error on the return path, possibly related to the two addresses. I just spent over an hour on the phone with my ISP's tech support, including 2nd level. They agree there's likely a problem in their network causing this issue.

[johnpoz]

Why would pfsense answer you - you didn't send the traffic to pfsense you sent it to your casa mac address - why would pfsense answer that.. Its not sent to is interface... Look at your pcap - your send it to a 00:17:10:X:X:X via mac which is NOT pfsense is it?? Unless your pfsense is using an interface made by casa?? ;)

You can not expect pfsense to send you back an answer to something that was not SENT to it..

Look again at your pcap...

Are you saying this is pfsense mac address of its interface on your lan side?

that 00:17:10 mac

Even if your ISP was not answering trace - you would still see the first hop from pfsense... But I find it hard to believe that 00:17:10 mac is pfsense lan side interface.. Since I show it being casa (my bad read it as 00:17:00 (arris) before... They make modems... So that is the mac of your ISP device?

[JKnott]

@johnpoz

Sorry, I must have uploaded the wrong capture. I just ran Wireshark again and here's the capture.

0_1548087760571_capture.pcapng

Even if your ISP was not answering trace - you would still see the first hop from pfsense...

That is what I expect too. Here again is what happens:

IPv6 - No response from hops beyond pfSense expected due to ISP problem.
$ traceroute -6 www.yahoo.com
traceroute to www.yahoo.com (2001:4998:58:1836::11), 30 hops max, 80 byte packets
1 * * * < I should see the pfSense firewall here
2 * * *
3 * * *
4 * * *
5 * * *
6 * * *
7 * * *
8 * * *
9 * * *

IPv4
$ traceroute -4 www.yahoo.com
traceroute to www.yahoo.com (72.30.35.10), 30 hops max, 60 byte packets
1 [host name removed to protect the guilty] (172.16.0.1) 0.247 ms 0.231 ms 0.219 ms
2 * * *
3 24.156.150.217 (24.156.150.217) 19.862 ms 20.057 ms 20.276 ms
4 0-5-0-6-cgw01.wlfdle.rmgt.net.rogers.com (209.148.233.169) 19.217 ms 0-4-0-6-cgw01.wlfdle.rmgt.net.rogers.com (209.148.233.165) 18.898 ms 0-5-0-6-cgw01.wlfdle.rmgt.net.rogers.com (209.148.233.169) 19.604 ms
5 209.148.237.5 (209.148.237.5) 39.950 ms 209.148.230.26 (209.148.230.26) 39.410 ms 39.699 ms
6 * * *
7 UNKNOWN-216-115-110-X.yahoo.com (216.115.110.238) 50.284 ms ae-4-0.pat1.nyc.yahoo.com (216.115.104.121) 38.405 ms UNKNOWN-216-115-110-X.yahoo.com (216.115.110.236) 40.179 ms
8 ae-0.pat2.bfw.yahoo.com (216.115.111.30) 74.575 ms ae-1.pat1.bfw.yahoo.com (216.115.111.28) 48.381 ms 48.484 ms
9 et-1-0-0.msr2.bf1.yahoo.com (74.6.227.45) 44.879 ms^C

Here's what I get when I run traceroute6 on pfSense
raceroute6 www.yahoo.com
traceroute6: Warning: atsv2-fp-shed.wg1.b.yahoo.com has multiple addresses; using 2001:4998:58:1836::11
traceroute6 to atsv2-fp-shed.wg1.b.yahoo.com (2001:4998:58:1836::11) from 2607:f798:804:90:75f6:4cc0:abcd:xyz, 64 hops max, 20 byte packets
1 * * *
2 2607:f798:10:10d2:0:241:5615:217 12.761 ms 12.572 ms 11.274 ms
3 2607:f798:10:31a:0:2091:4823:3165 19.792 ms
2607:f798:10:349:0:2091:4823:5109 12.531 ms
2607:f798:10:31b:0:2091:4823:3169 20.734 ms
4 2607:f798:10:370:0:2091:4823:7005 26.660 ms
2607:f798:10:d6:0:640:7124:1110 32.538 ms
2607:f798:10:10cf:0:2091:4823:3106 26.588 ms
5 2607:f798:14:2::310 27.666 ms 32.706 ms 24.959 ms
6 2001:4998:f003:224:: 28.924 ms

[johnpoz]

Ok I take it that is your pfsense interface at the 00:16:17 mac..

So did you edit your icmp redirects in tunables? Should be a 1

If you set that for 0 for IPv6, then that would explain why you get them for IPv4 and not for IPv6

[JKnott]

@johnpoz said in IPv6 traceroute not showing first hop (pfSense):

So did you edit your icmp redirects in tunables? Should be a 1

It's set to 1. However, wouldn't that setting affect redirects, when a packet is not supposed to pass through a router? Traceroute is supposed to receive an ICMP message, when the hop limit decrements to 0, which has nothing to do with redirects.

[johnpoz]

When the TTL does not allow it to be forwarded, it sends you a ICMP does it not. I guess I could reboot mine changing it to 0 and see if causes the problem. But that was the only guess I had at the time which could cause that problem..

There might be some other tunable that could cause it not to send the ICMP message I guess. Out of the box this should just work... If its sending the traffic to pfsense, out of the box pfsense should send the ICMP v6 message when TTL on does not allow it to forward.

[JKnott]

@johnpoz said in IPv6 traceroute not showing first hop (pfSense):

Out of the box this should just work.

That is my expectation too. I should at least see a response from pfSense. I just ran Wireshark again and do not see any response at all on IPv6, but see all the TTL exceeded messages on IPv4. As I mentioned above, I'm not expecting response from anything beyond pfSense on IPv6, due to the ISP problem. I'll have to try again after that's been resolved. However, I'd be very surprised if that problem caused pfSense to not respond.

[johnpoz]

So do you have any rules in say floating that would stop the udp... Did you try with icmp vs udp?

Where exactly are you sniff at... The client machine or pfsense interface?