From nobody Sat Jul 06 00:17:39 2024 X-Original-To: freebsd-net@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4WG9vK3cfKz5Nx3x for ; Sat, 06 Jul 2024 00:17:49 +0000 (UTC) (envelope-from freebsd-rwg@gndrsh.dnsmgr.net) Received: from gndrsh.dnsmgr.net (pdx.rh.CN85.dnsmgr.net [65.75.216.6]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4WG9vK0s8Zz4JCC for ; Sat, 6 Jul 2024 00:17:48 +0000 (UTC) (envelope-from freebsd-rwg@gndrsh.dnsmgr.net) Authentication-Results: mx1.freebsd.org; none Received: from gndrsh.dnsmgr.net (localhost [127.0.0.1]) by gndrsh.dnsmgr.net (8.13.3/8.13.3) with ESMTP id 4660Heno030550; Fri, 5 Jul 2024 17:17:40 -0700 (PDT) (envelope-from freebsd-rwg@gndrsh.dnsmgr.net) Received: (from freebsd-rwg@localhost) by gndrsh.dnsmgr.net (8.13.3/8.13.3/Submit) id 4660HdGk030549; Fri, 5 Jul 2024 17:17:39 -0700 (PDT) (envelope-from freebsd-rwg) From: "Rodney W. Grimes" Message-Id: <202407060017.4660HdGk030549@gndrsh.dnsmgr.net> Subject: Re: OpenVPN suddenly working one way only In-Reply-To: <20bf2eb4-7ed9-4c6f-8cfb-41d96073113c@netfence.it> To: Andrea Venturoli Date: Fri, 5 Jul 2024 17:17:39 -0700 (PDT) CC: "Rodney W. Grimes" , Ronald Klop , freebsd-net@FreeBSD.org X-Mailer: ELM [version 2.4ME+ PL121h (25)] List-Id: Networking and TCP/IP with FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-net List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-net@FreeBSD.org MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII X-Spamd-Bar: ---- X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:10494, ipnet:65.75.216.0/23, country:US] X-Rspamd-Queue-Id: 4WG9vK0s8Zz4JCC > On 7/5/24 16:32, Rodney W. Grimes wrote: > > >> However, I just changed UDP port and it seems to work! > > The "solution" didn't last: after a little more than 3 hours, this > tunnel stopped working again :( > > Strangely restarting openvpn on both sides fixed this, this time. > > > > > > Or host A has a zombie process with a UDP listen on the port? > > It's host B listening as a server: host A connects to it. > So I guess I should look into host B... Host A *still* has/had a port open, and that port can lingere for several reasons, and that can cause issues. It can also happen on Host B, but we always look there, right? What I am getting at is you shouldnt assume the problem could not be on the orignating(client) end. > > And no, "netstat -na" show no udp4 line with the choosen port, after I > stop openvpn. Ok, good, check both A and B. > > To my ignorance, this reminds me of the "no buffer space available" I > sometimes get with ping. Thats usually a stuffed up tunnel that can't transmit for some reason. ppp will do this if it things the link is down for any reason. > That's just a wild guess, of course, but I suspect something is wrong > with UDP on the "server" host... MTU's? Have you manually checked path MTU to make sure that it can carry your payload correctly IN BOTH DIRECTIONS. I have seen asymetrical routes cause MTU issues due to it being smaller in one direction. > bye & Thanks > av. -- Rod Grimes rgrimes@freebsd.org