WEP "open" mode?

[Ian Goldberg]

My desktop acts as my 802.11 gateway.  It's running orinoco_cs in ad-hoc
mode, using a 104-bit WEP key.  In wireless.opts I have:

KEY="16284....ae6f open"

The idea is that I want *my* machines to use WEP, but I want to allow
*visitors* (and random warwalkers) to be able to use the node without
WEP.

If I do tcpdump, what I see is that the desktop can in fact see the
unencrypted packets from the visitors, but the _replies_ it sends are
always encrypted.  :-(

Have I set up something wrong?

Thanks,

   - Ian