Date: Thu, 15 Jan 2004 11:11:41 -0800 (PST) From: Julian Elischer <julian@elischer.org> To: Vlad Galu <dudu@diaspar.rdsnet.ro> Cc: freebsd-net@freebsd.org Subject: Re: Dummy Network Interface Message-ID: <Pine.BSF.4.21.0401151109180.26778-100000@InterJet.elischer.org> In-Reply-To: <20040115053524.2c6e8db2.dudu@diaspar.rdsnet.ro>
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On Thu, 15 Jan 2004, Vlad Galu wrote: > Robert Watson <rwatson@freebsd.org> writes: > > | > |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. ng_iface <-> ng_hole would yield a 'black hole' interface if that is what is being looked for.. ng_iface is similar to both tun and tap exceot that it can route the packets to arbitrary netgraph moudles or to any subsystem to which netgraph has a supported interface. (e.g. userland or a tty) > > | > |Robert N M Watson FreeBSD Core Team, TrustedBSD Projects > |robert@fledge.watson.org Senior Research Scientist, McAfee > |Research > | > | > |_______________________________________________ > |freebsd-net@freebsd.org mailing list > |http://lists.freebsd.org/mailman/listinfo/freebsd-net > |To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" > | > > > ---- > If it's there, and you can see it, it's real. > If it's not there, and you can see it, it's virtual. > If it's there, and you can't see it, it's transparent. > If it's not there, and you can't see it, you erased it. >
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