From owner-freebsd-net@FreeBSD.ORG Thu Jan 15 18:24:47 2004 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 043E016A4CE for ; Thu, 15 Jan 2004 18:24:47 -0800 (PST) Received: from cust-65-110-28-221.sfu-resnet.connectwest.net (cust-65-110-28-221.sfu-resnet.connectwest.net [65.110.28.221]) by mx1.FreeBSD.org (Postfix) with ESMTP id F2DF043D46 for ; Thu, 15 Jan 2004 18:24:44 -0800 (PST) (envelope-from ms419@freezone.co.uk) Received: from fis.lat ([192.168.179.43])3.35 #1 (Debian)) id 1AhJf7-0005mF-00 for ; Thu, 15 Jan 2004 18:24:41 -0800 Mime-Version: 1.0 (Apple Message framework v609) In-Reply-To: <20040115204734.GA61637@gargantuan.com> References: <20040115053524.2c6e8db2.dudu@diaspar.rdsnet.ro> <20040115204734.GA61637@gargantuan.com> Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <220D0778-47CB-11D8-907F-000A95C71776@freezone.co.uk> Content-Transfer-Encoding: 7bit From: ms419@freezone.co.uk Date: Thu, 15 Jan 2004 18:24:38 -0800 To: freebsd-net@freebsd.org X-Mailer: Apple Mail (2.609) Subject: Re: Dummy Network Interface X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 16 Jan 2004 02:24:47 -0000 My apologies for such an undescriptive post. I am trying to run a kerberos KDC on a mobile system. Unfortunately, the KDC won't bind to the loopback device, and all interfaces are disabled by the operating system when they are inactive - there is no link detected. So I am trying to configure a device with a private IP address, the only purpose of which will be to connect to the local machine. On Jan 15, 2004, at 12:47 PM, Michael W. Oliver wrote: > On Thu, Jan 15, 2004 at 03:07:20PM -0500, Robert Watson wrote: >> >> On Thu, 15 Jan 2004, Vlad Galu wrote: >> >>> |On Tue, 13 Jan 2004 ms419@freezone.co.uk wrote: >>> | >>> |> How does one create a dummy network interface in FreeBSD? >>> | >>> |Dummy in what sense? An interface where the packets are simply >>> |dropped? if_tap and if_tun both provide pseudo-device in /dev that a >>> |userspace process can attach to in order to emulate a network >>> interface >>> |(used by VMWare, ppp, various tunneling bits, ...) In the absense >>> of a >>> |process sitting on the device, they simply drop the packets. >>> Although >>> |they may get garbage-collected if unused on -CURRENT... You can >>> also >>> |use netgraph to bring pseudo-interfaces, perhaps without anywhere >>> for >>> |packets to go. >>> | >>> |And, I suppose, create in what sense? Are you looking at this from >>> a >>> |developer perspective, or you just need one from a user perspective. >>> |If writing a device driver (and hence needing a starting point), >>> if_tap >>> |and if_tun are fairly decent models for a pseudo-interface. >>> >>> I think he could use the discard interface smoothly. On Linux >>> (from which the dummy interface notion is taken from) it is simply >>> used >>> for testing purposes, as in routing, or perhaps socket programming. I >>> personally have used it for a while, but then I used interface >>> aliasing, >>> which became a habit. >> >> Does the discard interface in Linux "act like" another type of >> interface, >> such as point-to-point, ethernet, etc? > > I believe that he was referring to the discard interface in FreeBSD. I > don't know about Linux at all, but I have used the discard interface in > a FreeBSD router much like a Null interface in a cisco router. > > pseudo-device disc > > man 4 disc > > -- > Mike > perl -e 'print unpack("u","88V]N=&%C=\"!I;F9O(&EN(&AE861E