Dummy Network Interface

[Vlad Galu]

Robert Watson <rwatson at freebsd.org> writes:

|
|On Tue, 13 Jan 2004 ms419 at 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.

|
|Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
|robert at fledge.watson.org      Senior Research Scientist, McAfee
|Research
|
|
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