Date: Thu, 15 Jan 2004 15:07:20 -0500 (EST) From: Robert Watson <rwatson@freebsd.org> To: Vlad Galu <dudu@diaspar.rdsnet.ro> Cc: freebsd-net@freebsd.org Subject: Re: Dummy Network Interface Message-ID: <Pine.NEB.3.96L.1040115150648.74950A-100000@fledge.watson.org> In-Reply-To: <20040115053524.2c6e8db2.dudu@diaspar.rdsnet.ro>
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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? Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Senior Research Scientist, McAfee Research
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