From nobody Thu Nov 30 03:34:59 2023 X-Original-To: questions@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 4Sghf34ytJz52gNG for ; Thu, 30 Nov 2023 03:35:07 +0000 (UTC) (envelope-from Olivier.Nicole@cs.ait.ac.th) Received: from mail.cs.ait.ac.th (mail.cs.ait.ac.th [192.41.170.16]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4Sghf14MYzz4DRC for ; Thu, 30 Nov 2023 03:35:05 +0000 (UTC) (envelope-from Olivier.Nicole@cs.ait.ac.th) Authentication-Results: mx1.freebsd.org; dkim=pass header.d=cs.ait.ac.th header.s=selector1 header.b=EnW5X9a7; spf=pass (mx1.freebsd.org: domain of Olivier.Nicole@cs.ait.ac.th designates 192.41.170.16 as permitted sender) smtp.mailfrom=Olivier.Nicole@cs.ait.ac.th; dmarc=pass (policy=none) header.from=cs.ait.ac.th Received: from mail.cs.ait.ac.th (localhost [127.0.0.1]) by mail.cs.ait.ac.th (Postfix) with ESMTP id 76BE63AB04 for ; Thu, 30 Nov 2023 10:35:00 +0700 (+07) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cs.ait.ac.th; h= content-type:content-type:mime-version:message-id:date:date :subject:subject:from:from:received:received:received; s= selector1; t=1701315300; x=1703129701; bh=9mNvoFSgcTma8+orkgB4EM sdRdZbZgWSV2Mi9HThMH0=; b=EnW5X9a7ImC7nk5ondUNc/rxhZjp5NkmQPRMGz +OljmvqFUxLhxBLkFfUpHIxzq2588Fu1FyNOfWZzJZeHpF39CZGu/SIWpf5R29+l tsgohBuDXKsMCS6D+vH4vEjyz5y2Mvyl9LoKd6hohp0v0Jo6dM75EWEQcwltmr9/ TtewE= X-Virus-Scanned: amavisd-new at cs.ait.ac.th Received: from mail.cs.ait.ac.th ([127.0.0.1]) by mail.cs.ait.ac.th (mail.cs.ait.ac.th [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id MGWnjMhVwCBc for ; Thu, 30 Nov 2023 10:35:00 +0700 (+07) Received: from banyan.cs.ait.ac.th (banyan.cs.ait.ac.th [192.41.170.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.cs.ait.ac.th (Postfix) with ESMTPS id 45A613AB02 for ; Thu, 30 Nov 2023 10:35:00 +0700 (+07) Received: (from on@localhost) by banyan.cs.ait.ac.th (8.15.2/8.15.2/Submit) id 3AU3YxXf028620; Thu, 30 Nov 2023 10:34:59 +0700 (ICT) (envelope-from on@banyan.cs.ait.ac.th) From: Olivier To: questions@freebsd.org Subject: tap interface forcing a permanent ARP association Date: Thu, 30 Nov 2023 10:34:59 +0700 Message-ID: List-Id: User questions List-Archive: https://lists.freebsd.org/archives/freebsd-questions List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-questions@freebsd.org X-BeenThere: freebsd-questions@freebsd.org MIME-Version: 1.0 Content-Type: text/plain X-Spamd-Result: default: False [-4.70 / 15.00]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-1.000]; DMARC_POLICY_ALLOW(-0.50)[cs.ait.ac.th,none]; RCVD_DKIM_ARC_DNSWL_MED(-0.50)[]; R_DKIM_ALLOW(-0.20)[cs.ait.ac.th:s=selector1]; R_SPF_ALLOW(-0.20)[+mx]; RCVD_IN_DNSWL_MED(-0.20)[192.41.170.16:from]; MIME_GOOD(-0.10)[text/plain]; FROM_EQ_ENVFROM(0.00)[]; MLMMJ_DEST(0.00)[questions@freebsd.org]; DKIM_TRACE(0.00)[cs.ait.ac.th:+]; RCVD_TLS_LAST(0.00)[]; MID_RHS_MATCH_FROMTLD(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_COUNT_THREE(0.00)[4]; PREVIOUSLY_DELIVERED(0.00)[questions@freebsd.org]; RCPT_COUNT_ONE(0.00)[1]; TO_DN_NONE(0.00)[]; ASN(0.00)[asn:4767, ipnet:192.41.170.0/24, country:TH] X-Rspamd-Queue-Id: 4Sghf14MYzz4DRC X-Spamd-Bar: ---- Hi, I have an OpenVPN server running on FreeBSD (13.2-p5). I have included the following in /etc/rc.conf: cloned_interfaces="tap0 bridge0" ifconfig_bridge0="addm vmx0 addm tap0" ifconfig_tap0="UP" openvpn_enable="YES" And it works fine, except that ip maps the MAC address of tap0 to the IP of my web server (on another machine), and the mapping is "permament": www.cs.ait.ac.th (10.41.170.42) at aa:bb:cc:dd:ee:ff on tap0 permanent [ethernet] That has two adverse effects: - any VPN client cannot access my web server as they would get a wrong MAC address; - the VPN server will sometime reply to an ARP request on my LAN, providing an obviously wrong answer. Poking around, I found out that it was due to the "ifconfig_tap0=UP" line. Further more, that line is not needed for OpenVPN to start properly; so I have disabled it. But I would like to understand why turning up the tap interface causes it to update the ARP table. Best regards, Olivier --