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Date:      Mon, 22 May 2023 10:35:56 +0100
From:      Alexander Chernikov <melifaro@FreeBSD.org>
To:        "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net>
Cc:        net@freebsd.org
Subject:   Re: connection loss related to ndp?
Message-ID:  <0BA534C4-EA11-46C0-B225-B18CD2C37F07@FreeBSD.org>
In-Reply-To: <ors2q662-73q8-5s64-9082-3oqs042q3orq@yvfgf.mnoonqbm.arg>
References:  <ors2q662-73q8-5s64-9082-3oqs042q3orq@yvfgf.mnoonqbm.arg>

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> On 22 May 2023, at 00:34, Bjoern A. Zeeb =
<bzeeb-lists@lists.zabbadoz.net> wrote:
>=20
> Hi,
Hi Bjoern,
>=20
> I am on 14-CUREENT (6fa88a4ad35e from April) and I recently started to
Could you please check if that=E2=80=99s a local commit? I=E2=80=99m not =
able to find this one in -main.
> experience something which looks like:
>=20
> ping6 -n ff02::1%wlan0 works
> ping6 -n host works
Is =E2=80=98host=E2=80=99 a global unicast address reachable via the =
default route?
>=20
> but ssh to host hangs.  Given this seemed to be periodic-ish and I =
only
> always notice way after the facts I started to poke around and found:
>=20
> ndp -P
> ndp -R
> rtsol wlan0
>=20
> fixes things.
>=20
>=20
> I've seen similar problems with NDP vs. routing table updates and
> another rtsol call would not bring back the default route unless
> ndp -R was run before and I wonder if these are connected.
>=20
> Both have become a bit annoying problems on a day-to-day IPv6-only =
usage
> for me that I had never experienced like this (in the last decade) =
before.
>=20
> If anyone has ideas and saves me from spending too many hours digging
> into this now I'd appreciate.
There were a number of changes related to routing/ndp (by me) and PCB =
table split work, so there are multiple candidates for the issue.
I=E2=80=99d start with checking with tcpdump (w/o promisc) output when =
running ssh. Specifically, checking if
* SYN is sent to the right destination with the right source address
* Destination MAC is correct
* S+A Is received
I=E2=80=99d also check if NDP record for the default GW looks sane & =
check the PCB status while SSH is trying to connect.

>=20
> /bz
>=20
> --=20
> Bjoern A. Zeeb                                                     =
r15:7
>=20




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