Date: Mon, 15 Sep 2025 19:15:03 +0100 From: Roy Marples <roy@marples.name> To: "Karl Denninger" <karl@denninger.net> Cc: "Freebsd net" <freebsd-net@freebsd.org> Subject: Re: IPv6 networking problems in 14.3 Message-ID: <1994e966819.20444a00373298.5175621979752895403@marples.name> In-Reply-To: <dda91d8e-2a27-4af6-8c3b-06c84a60fc7f@denninger.net> References: <4C00D174-21FE-47C4-A30A-A382138571A5@keehole.org> <A9EBD993-D77D-49F9-9FFB-0E42EA0BEE6E@keehole.org> <DC84D8EC-B084-4AF1-B3F4-413323DA613A@distal.com> <dfa7af0c-334f-4b36-86dc-b2d75d1477d3@denninger.net> <E06E4F40-0E2C-4C4E-9C27-3BCF086347FA@distal.com> <6fce77fb-9ba8-4c7b-bb9b-0e337d91f278@denninger.net> <1780EFAC-DA9C-4593-BE37-28E7FFCE4388@distal.com> <6e7a8fc6-12c8-4097-ad70-bcb1e4967ade@denninger.net> <092f8b7a-9b98-4e2a-b6c5-361b40549cce@denninger.net> <A8F67A5F-70B1-4336-B6AA-FBAC48F7000C@distal.com> <dda91d8e-2a27-4af6-8c3b-06c84a60fc7f@denninger.net>
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[-- Attachment #1 --]
dhcpcd already has this behaviour.
Good luck!
Roy
---- On Mon, 15 Sep 2025 18:59:15 +0100 Karl Denninger<karl@denninger.net> wrote ----
On 9/15/2025 13:20, Chris Ross wrote:
On Sep 15, 2025, at 08:59, Karl Denninger
mailto:karl@denninger.net wrote:
Hmmmmm.... just came in via git pull:
dhclient: improve UDP checksum handling
This could potentially apply to other bpf-using things
-- which includes dhcpcd. And you have tso/lro turned
on.
It is a patch to dhclient, not dhcpcd but does the same
issue potentially apply?
I don’t know, but I think that isn’t my problem. It seems like
the NS that
dhcpcd is sending is alright, and tcpdump doesn’t see an NA
coming
back in at all.
- Chris
Unfortunately without being able to snoop on the ONT's glass side
that's hard to diagnose; are they sending it at all, are they
sending it to the wrong place, does the ONT have a map that's
wrong between its fiber interface and the MAC connected to it,
etc.
Fortunately the ISP I'm connected to when this sort of thing
happened to me had people who actually knew what they were doing
and were able to snoop the packets coming and going on their side
when I was on the phone with them. Good luck getting a large ISP
like Verizon to connect you to someone with the appropriate level
of access into their gear to be able to do that. It took me a
couple of rounds with KUB here before they went beyond "we cleared
our ARP table entry for your ONT but we don't know why it did
that" to getting someone on the line that actually was willing and
able to snoop the traffic and determine WHY it happened.
The interesting part in this case (but probably the fortunate
part!) was that their infrastructure for delegating an IPv4
(single address, you do the NAT) and /56 IPv6 is apparently
entirely distinct thus that one had a hissy fit didn't prevent the
other from coming up and functioning.
--
Karl Denninger
mailto:karl@denninger.net
The Market Ticker
[S/MIME encrypted email preferred]
[-- Attachment #2 --]
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta content="text/html;charset=UTF-8" http-equiv="Content-Type"></head><body ><div style='font-size:10pt;font-family:Verdana,Arial,Helvetica,sans-serif;color:#000000;'><div ><div>dhcpcd already has this behaviour.</div><div><br></div><div>Good luck!</div><div><br></div><div><div>Roy</div></div> <br> </div><div class="zmail_extra_hr" style="border-top-width: 1px; border-top-style: solid; border-top-color: rgb(204, 204, 204); height: 0px; margin-top: 10px; margin-bottom: 10px; line-height: 0px;"></div> <br> <div class="replyHeader">---- On Mon, 15 Sep 2025 18:59:15 +0100 Karl Denninger<karl@denninger.net> wrote ----</div><div><br></div><blockquote style="border-left: 0px; padding-left: 0px; margin-left: 0px;"> <meta content="text/html; charset=UTF-8">
<div>
<div class="x_630959011moz-cite-prefix">On 9/15/2025 13:20, Chris Ross wrote:<br>
</div>
<blockquote><br>
<div>
<blockquote>
<div>On Sep 15, 2025, at 08:59, Karl Denninger
<a class="x_630959011moz-txt-link-rfc2396E" href="mailto:karl@denninger.net" target="_blank"><karl@denninger.net></a> wrote:</div>
<br class="x_630959011Apple-interchange-newline">
<div>
<meta content="text/html; charset=UTF-8">
<div>
<p>Hmmmmm.... just came in via git pull:</p>
<p> dhclient: improve UDP checksum handling<br>
<br>
This could potentially apply to other bpf-using things
-- which includes dhcpcd. And you have tso/lro turned
on.</p>
<p>It is a patch to dhclient, not dhcpcd but does the same
issue potentially apply?</p>
</div>
</div>
</blockquote>
<div><br>
</div>
I don’t know, but I think that isn’t my problem. It seems like
the NS that</div>
<div>dhcpcd is sending is alright, and tcpdump doesn’t see an NA
coming</div>
<div>back in at all.</div>
<div><br>
</div>
<div>- Chris</div>
<div><br>
</div>
</blockquote>
<p>Unfortunately without being able to snoop on the ONT's glass side
that's hard to diagnose; are they sending it at all, are they
sending it to the wrong place, does the ONT have a map that's
wrong between its fiber interface and the MAC connected to it,
etc.</p>
<p>Fortunately the ISP I'm connected to when this sort of thing
happened to me had people who actually knew what they were doing
and were able to snoop the packets coming and going on their side
when I was on the phone with them. Good luck getting a large ISP
like Verizon to connect you to someone with the appropriate level
of access into their gear to be able to do that. It took me a
couple of rounds with KUB here before they went beyond "we cleared
our ARP table entry for your ONT but we don't know why it did
that" to getting someone on the line that actually was willing and
able to snoop the traffic and determine WHY it happened.</p>
<p>The interesting part in this case (but probably the fortunate
part!) was that their infrastructure for delegating an IPv4
(single address, you do the NAT) and /56 IPv6 is apparently
entirely distinct thus that one had a hissy fit didn't prevent the
other from coming up and functioning.</p>
<div class="x_630959011moz-signature">-- <br>
Karl Denninger<br>
<a href="mailto:karl@denninger.net" class="x_630959011moz-txt-link-freetext" target="_blank">karl@denninger.net</a><br>
<i>The Market Ticker</i><br>
<font size="-2"><i>[S/MIME encrypted email preferred]</i></font></div>
</div> </blockquote></div><br></body></html>
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