[RESOLVED] --was: Re: TCP 3-way-handshake fails

Axel Rau Axel.Rau at chaos1.de
Wed Dec 18 11:47:32 UTC 2019

After router startup, its routingtable shows entries like this:

2a05:bec0:26:2::70                 0c:c4:7a:ce:9e:90       UHLc
2a05:bec0:26:2::71                 link#1                  UHLc

The 2nd one is an alias address for the 1st one (a jail).

After ping6 from the router to this 2nd address, it looks as expected:

fw1# ping6 2a05:bec0:26:2::71
2a05:bec0:26:2::70                 0c:c4:7a:ce:9e:90       UHLc
2a05:bec0:26:2::71                 0c:c4:7a:ce:9e:90       UHLc

The reason for this misbehaviour was that I disabled auto linklocal
(-auto_linklocal in rc.conf).


> Am 10.12.2019 um 11:40 schrieb Axel Rau <Axel.Rau at chaos1.de>:
> Hi all
> I have a fancy behaviour on a FreeBSD 12.1 box, with
> some servers (e.g. rsyslogd, nginx) which happens with
> some clients, with others not (both are in the same sub-
> nets). Everything is dualstack. Disabling IPv6, stops
> the problem.
> The traffic is routed via 2 firewalls OpenBSD 6.6)
> and a VPN.
> I attach 2 textfiles (tcpdump) with an extracted flow:
> gw1, the OpenBSD side
> db3: the FreeBSD side
> I also include an example, where the problem
> does not happen: db3,ok.txt
> Which details needs to be collected to insulate
> the problem?
> Any help is very welcome,
> Axel
> <gw1.32404.txt><db3.32404.txt><db3.ok.txt>
> ---
> PGP-Key: CDE74120  ☀  computing @ chaos claudius

PGP-Key: CDE74120  ☀  computing @ chaos claudius

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