Virtual WiFi on Linux?

Jouni Malinen jkmaline
Wed Oct 19 10:23:28 PDT 2005

On Wed, Oct 19, 2005 at 09:37:08AM -0700, Ben Greear wrote:

> If someone could implement the ability to make one WiFi NIC appear to
> be multiple NICs, even if connected to the same AP, it would be something
> that my company is interested in sponsoring.
> The requirements would be something like:
> * Each virtual interface is a real net-device with it's own IP, MAC and (potentially) WiFi settings.
> * To the AP, it appears as if N laptops/PCs are connected to it sending & receiving pkts.

The IEEE 802.11 stack released by Devicescape couple of weeks ago under
GPLv2 (see netdev mailing list for some discussion) supports this kind
of functionality. In other words, you can create multiple virtual
netdevs and have each one act as a separate client. Since each clients
shows up as a netdev in the kernel, you can do whatever you want with
them, i.e., own IP address and all other protocols supported by Linux
should work fine. However, sending IP packets between different IP
addresses of the same host is going to require some kernel patching.

Since this is using multiple MAC addresses over air, one will of course
have to use hardware that actually supports this.

> My goal is to use this for testing purposes to do AP loading and such.

This is indeed one of the main uses for this feature (though not the
only one). I've emulated more than 2000 stations with one Atheros radio
with this implementation.

Another use is to do this virtual Wi-Fi thing properly ;-), i.e.,
without triggering re-association and jumping between APs or being
limited to plaintext mode. The current implementation does not support
multiple channels (i.e., you need to have one radio for each channel),
but if someone had real use for being able to talk with one radio to
multiple APs on different channels, some kind of more intellegent
channel hopping with power save use could be implemented.

Jouni Malinen                                            PGP id EFC895FA

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