From owner-freebsd-net@freebsd.org Tue Jun 21 09:33:04 2016 Return-Path: Delivered-To: freebsd-net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id DDB8CAC5ECF for ; Tue, 21 Jun 2016 09:33:04 +0000 (UTC) (envelope-from freebsd@grem.de) Received: from mail.grem.de (outcast.grem.de [213.239.217.27]) by mx1.freebsd.org (Postfix) with SMTP id 501F92753 for ; Tue, 21 Jun 2016 09:33:03 +0000 (UTC) (envelope-from freebsd@grem.de) Received: (qmail 61100 invoked by uid 89); 21 Jun 2016 09:25:40 -0000 Received: from unknown (HELO bsd64.grem.de) (mg@grem.de@194.97.158.70) by mail.grem.de with ESMTPA; 21 Jun 2016 09:25:40 -0000 Date: Tue, 21 Jun 2016 11:25:38 +0200 From: Michael Gmelin To: freebsd-net@freebsd.org Cc: stdin@niklaas.eu Subject: Re: ARP table entries / ifconfig needs to be issued twice when moving IP Message-ID: <20160621112538.784e7b6e@bsd64.grem.de> In-Reply-To: <20160621064800.GB8441@box-hlm-03.niklaas.eu> References: <20160621064800.GB8441@box-hlm-03.niklaas.eu> X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.29; amd64-portbld-freebsd10.2) X-Face: $wrgCtfdVw_H9WAY?S&9+/F"!41z'L$uo*WzT8miX?kZ~W~Lr5W7v?j0Sde\mwB&/ypo^}> +a'4xMc^^KroE~+v^&^#[B">soBo1y6(TW6#UZiC]o>C6`ej+i Face: iVBORw0KGgoAAAANSUhEUgAAADAAAAAwBAMAAAClLOS0AAAAJFBMVEWJBwe5BQDl LASZU0/LTEWEfHbyj0Txi32+sKrp1Mv944X8/fm1rS+cAAAACXBIWXMAAAsTAAAL EwEAmpwYAAAAB3RJTUUH3wESCxwC7OBhbgAAACFpVFh0Q29tbWVudAAAAAAAQ3Jl YXRlZCB3aXRoIFRoZSBHSU1QbbCXAAAAAghJREFUOMu11DFvEzEUAGCfEhBVFzuq AKkLd0O6VrIQsLXVSZXoWE5N1K3DobBBA9fQpRWc8OkWouaIjedWKiyREOKs+3PY fvalCNjgLVHeF7/3bMtBzV8C/VsQ8tecEgCcDgrzjekwKZ7TwsJZd/ywEKwwP+ZM 8P3drTsAwWn2mpWuDDuYiK1bFs6De0KUUFw0tWxm+D4AIhuuvZqtyWYeO7jQ4Aea 7jUqI+ixhQoHex4WshEvSXdood7stlv4oSuFOC4tqGcr0NjEqXgV4mMJO38nld4+ xKNxRDon7khyKVqY7YR4d+Cg0OMrkWXZOM7YDkEfKiilCn1qYv4mighZiynuHHOA Wq9QJq+BIES7lMFUtcikMnkDGHUoncA+uHgrP0ctIEqfwLHzeSo+eUA66AqzwN6n 2ZHJhw6Qh/PoyC/QENyEyC/AyNjq74Bs+3UH0xYwzDUC4B97HgLocg1QLYgDDO1v f3UX9Y307Ew4AHh67YAFFsxEpkXwpXY3eIgMhAAE3R19L919nNnuD2wlPcDE3UeT L2ytEICQib9BXgS2fU8PrD82ToYO1OEmMSnYTjSqSv9wdC0tPYC+rQRQD9ESnldF CyqfmiYW+tlALt8gH2xrMdC/youbjzPXEun+/ReXsMCDyve3dZc09fn2Oas8oXGc Jj6/fOeK5UmSMPmf/jL+GD8BEj0k/Fn6IO4AAAAASUVORK5CYII= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 21 Jun 2016 09:33:05 -0000 > Reminds me of what I encountered recently with two virtual > machines at my provider. I haven't further dug into this, as > I didn't check `arp -an`, but what I saw was switching an IP > address from hosts A to B resulted in pings from host C to arrive > at A. Host C said they got lost while tcpdump showed incoming > packets at A although they should have gone to B. As the packets came from host C, this is expected behaviour. Host C had the ARP entry cached (or if it wasn't on the same network, some network equipment had). What I'm describing is the machine having the IP address configured not creating a permanent entry in the local ARP table for its own interface. - Michael -- Michael Gmelin