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Subject: Re: OpenVPN suddenly working one way only
From: Michael Tuexen <michael.tuexen@lurchi.franken.de>
In-Reply-To: <AC8533A8-F877-4934-8907-6532C44D9CF7@punkt.de>
Date: Sat, 6 Jul 2024 18:24:10 +0200
Cc: Andrea Venturoli <ml@netfence.it>,
 "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>
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References: <202407061502.466F28cR033040@gndrsh.dnsmgr.net>
 <dd0115c5-f07b-4f3c-8158-ed2594011890@netfence.it>
 <AC8533A8-F877-4934-8907-6532C44D9CF7@punkt.de>
To: "Patrick M. Hausen" <hausen@punkt.de>
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> On 6. Jul 2024, at 18:13, Patrick M. Hausen <hausen@punkt.de> wrote:
>=20
> Hi all,
>=20
>> Am 06.07.2024 um 18:07 schrieb Andrea Venturoli <ml@netfence.it>:
>> It's almost surely due to a problem with the UDP packets that =
implement the VPN: again, according to tcpdump they go out host B, but =
never reach host A.
>=20
> Is it remotely possible that one of the ISPs blocks these UDP packets =
as part
> of an automatic "DoS protection" mechanism?
Or are any kind of NAT or Firewall involved which might loose state?
Are you using public addresses on host A and B?

Best regards
Michael
>=20
> Kind regards,
> Patrick
> --=20
> punkt.de GmbH
> Patrick M. Hausen
> .infrastructure
>=20
> Sophienstr. 187
> 76185 Karlsruhe
>=20
> Tel. +49 721 9109500
>=20
> https://infrastructure.punkt.de
> info@punkt.de
>=20
> AG Mannheim 108285
> Gesch=C3=A4ftsf=C3=BChrer: Daniel Lienert, Fabian Stein
>=20