wireless.opt options for different reasons

Jim Carter jimc at math.ucla.edu
Thu Sep 26 05:38:44 EST 2002

On Wed, 25 Sep 2002, Rob wrote:

> Is there a site or book that describes ALL options for wireless.opt for the
> different situations or explains the different options?

What do you expect, Microsoft tech writers?  :-)  Seriously, it's a very
appropriate request.  Jean Tourrilhes' page is a good place to start.

> The main thing is i am reading the 802.11 Wireless Networks Definitive Guide
> and it doesnt explain why we would want Managed over Ad-Hoc.

Good book.  My initial reasons for trying Ad-Hoc: you don't have to buy an
access point at (then) US$ 500 to 1000.  You have full control over the
configuration, which is handled by your linux box.

My reasons for switching to Managed mode now: There's a bad interaction
between firmware bugs (finger of blame points to Intersil I think) in
Ad-Hoc mode which, for jinxed people like me, drags the network throughput
down to 21 Kbyte/sec. Consumer-type AP's have greatly dropped in price:
Agere Orinoco AP-200 was US$ 160 last June, probably less now. Linksys
WAP-11 recently was $120, **cheaper** than a PCMCIA card and a PCI<->PCMCIA
converter to put it in, for a desktop machine. And you can more easily put
the AP on a high shelf, avoiding metallic obstructions, which were a
problem in my house. You can also hook up the Linksys AP as a "wireless
bridge", but we didn't actually try that.

> I would like
> to setup my linux box as a firewall (iptables, ipsec...freeswan, etc) and it
> doesnt give much info on how to do this...

The real info on security is scattered in various man pages and FAQs, none
of which are really relevant to wireless. In my own setup I assume that the
black hats are going to get onto my house network through my AP (or
Ad-Hoc), no matter how carefully I set it up, so my machines are able to
take care of themselves. But if you use WEP and turn off convenience
features (like telling the WEP key to compatible firmware over the aether -
"learn mode"), it can keep the local teenager from downloading MP3's over
your DSL connection. Also set up your DHCP to give an IP address only to
known MAC addresses, and similarly your firewall should pass only packets
from known MAC addresses. MAC can be spoofed, but likely the local teenager
won't take the trouble to actually *read* a FAQ about how to set the
parameter on the wireless card.

> The info that i am looking for is the options for:
> NWID		Ignore.  Let the firmware set it.
> MODE		See above for my preferences.
> FREQ		1-1 correspondence with channel.  Channel is easier to set.
> CHANNEL	Set this on the AP, in Managed mode.  Must be set
		explicitly in Ad-Hoc mode.  For efficient spectrum use at
		11 Mb/s, use 1, 6 or 11 (11 is not legal everywhere).
> SENS		Not sure what this is.
> RATE		Leave at default; cards will negotiate the fastest rate.
> KEY		Your WEP key.  Set this explicitly on the AP and the card.
> RTS		Irrelevant at home, and many firmwares can't even do it.
> FRAG		Irrelevant at home; take the default.
> OWCONFIG	Not sure what this is.
> IWSPY		In Ad-Hoc mode, tells the driver and the card which other
		card to report network quality statistics for.  Take the
		default in Managed mode -- the access point.
> IWPRIV	For engaging the obsolete Ad-Hoc Demo mode, and other wierd
		and wonderful effects that will probably mess you up.

James F. Carter          Voice 310 825 2897    FAX 310 206 6673
UCLA-Mathnet;  6115 MSA; 405 Hilgard Ave.; Los Angeles, CA, USA  90095-1555
Email: jimc at math.ucla.edu    http://www.math.ucla.edu/~jimc (q.v. for PGP key)

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