NULL or DUMMY parent interface to "park" interface setups?

[Nadrek]

Is there a way to set up a NULL or DUMMY parent interface?

I'd like to be able to set up a set of regular Interfaces (say, OPT2_AccessOtherWifi, OPT3_AccessOtherPhysicalNet, OPT4_ProvideOwnPhysicalNet, OPT5_ProvideOwnWifi, etc.) which are normally assigned to a NULL physical or WiFi parent interface (i.e. are disabled, but keep all their settings).

Then, when I'm at my friend's house with only physical networking, I could take my tiny physical pfSense firewall, or with a VMWare Player pfSense firewall, and plug in any one of my supported USB Ethernet adapters, assign OPT3_AccessOtherPhysicalNet to it, and then plug in any supported USB WiFi adapter and assign OPT5_ProvideOwnWifi to it, thus providing them with a (temporary) WiFi access point.

Similarly, at another friend's house with only WiFi , I could plug in a different USB WiFi adapter and assign OPT2_AccessOtherWifi to it, then plug in any supported USB Ethernet and assign OPT4_ProvideOwnPhysicalNet to it, plug it into my little switch, and have a firewalled physical network.

My basic question is: Before or after I unplug all the USB adapters, how do I "park" the interface assignments I've given, knowing that I may want to use an identical configuration with a different USB adapter next time?

My apologies if this has been answered before - if it has, I failed to search on the correct keywork.

P.S. The advanced variants include putting an OpenVPN connection in the middle of each of these, but I don't think that's relevant to the question.

[wallabybob]

@Nadrek:

Is there a way to set up a NULL or DUMMY parent interface?

Not with the functionality you describe. On startup pfSense complains if configured adapters aren't present and forces an interface reassignment from the console. Perhaps this behaviour could be changed to ignore missing adapters that weren't enabled.  (I haven't checked recently but I have a recollection that disabled adapters must be present to avoid the console reassignment dialogue.)

[Nadrek]

Thank you for the quick and useful answer.

What's the best way to put in a feature request for something like this?

[wallabybob]

A possible solution:
The PCI Atheros driver/chipset can operate as multiple WiFi Access Points. You could create multiple virtual interfaces, configure them and selectively enable them. The FreeBSD man page for the ath driver (http://www.freebsd.org/cgi/man.cgi?query=ath&apropos=0&sektion=0&manpath=FreeBSD+8.2-RELEASE&arch=default&format=html ) suggests multiple AP and client interfaces can operate concurrently. I have no experience with this feature. I can't recall reading any reports of anyone using a feature like this on supported USB WiFi devices.

[jimp]

the problem there is when you unplug the USB wireless you'd have to remove the interface assignment as well or it would drop to an interface reassignment prompt at bootup.

If you move a wireless interface config to a non-wireless interface, it wouldn't retain the wireless settings.