can I use wireless & wired cards together?

[David Wolfskill]

On Wed, Jun 15, 2005 at 04:33:42PM -0700, Gary Kline wrote:
> 	Sorry if this is a really dumb question, but can I buy a
> 	wireless NIC card for my 5.3 ThinkPad and have it
> 	Just-Work?  If not, how/where do I configure?  The 10-100
> 	card I've had since last July works flawlessly with my CAT5.

Well ... it depends.  :-}  On several things, such as:

* Precisely which interface(s) you want activiated under what
  circumstances.

* What sort of "wireless" environment you plan to use the card in.

Most of the places I want to use a wireless card, 802.11b is either all
that is supported or is adequate.  Several of those environments use WEP
(more as a form of "no trespassing" sign that any attempt at real
security); some of those also require that the access point have the MAC
address of the NIC in a "whitelist" and those APs are set up to not
broadcast the SSID.  So a certain amount of preparation (as a one-time
shot) is necessary in such cases.

My previous laptop (a Dell Inspiron 5000e) had no NICs built in, so
whenever I wanted to use a NIC, I inserted it.  I only had it using more
than one NIC at a given time a couple of times, so I was willing to hack
around and issue oddball commands manually to accomplish that; had I
wanted that mode of operation to be more common, more work would have
been called for.

In particular, at home, I have 2 "internal" networks -- a "trusted"
network and a "guest" network.  My access points are only on the guest
net, and access to the trusted net from the guest net is treated almost
the same as access to the trsuted net from the Internet -- effectively,
SSH to a designated host only.

My current laptop (a Dell Inspiron 8200) has both wired (xl0) and
wireless (wi0) NICs built in; this means that I needed to use a somewhat
different strategy for using the wired NIC when I wanted to do that --
after all, if I wanted to be on the wired net, there was usually a
reason for it (and being on the wireless net would not be an acceptable
substitute in my case).

In order to handle selecting the appropriate SSID WEP key, etc., I had
written a Perl script quite a while back, which I invoked from the
/etc/start_if.{an,wi}0 scriptlets.  Then after getting my current
laptop, I cobbled up an additional Perl script to drop any currently
active links, then look for any "wired" NICs (the script has a list of
wireless NIC regxen; NICs that don't match are treated as "wired) in
alphabetical order; if one is found that shows up as "active" (in
ifconfig's output), and attempt is made to make use of it.  If we get to
the end of all the wired NICs and none is active, it then tries to make
use of the first wireless NIC it finds (and invokes the previously-cited
script to do the wireless-specific dirty work).

So, once that sort of things has been handled, I'd think that things
pretty much ought to work, yeah.

Peace,
david
-- 
David H. Wolfskill				david at catwhisker.org
Any given sequence of letters is a misspelling of a great many English words.

See http://www.catwhisker.org/~david/publickey.gpg for public key.