[sclug] Home wireless lan

[Bob Franklin]

On Mon, 14 Jul 2003, Tim Sutton wrote:

> Can this can be done without a base station thingy?

The whole point of the 'ad hoc' mode is that you don't need a base
station; you can just put two (or more) devices in range and they will see
each other and chat.  So: 'yes'.

Obviously, that just sorts out the layer 2 side of things - so generally
you'll need to give them compatible IP addresses.  Windows 98+ and MacOS
(9+? definitely OS X) will use that 'autoconfiguration IP' range which
invents addresses beginning '169.254' and should just work, in the absence
of a DHCP server.  I don't know what the various DHCP clients for Linux
are doing, these days.

Obviously, this does mean you've have no DNS and dynamic IPs, so probably
the only way for two machines to usefully find each other is the dreaded
Windows 'Network Neighborhood' (or 'Computers Near Me' as it seems to be
called these days).  Mac OS X machines have 'Rendezvous' which does some
clever discovery and service location stuff.

Under [say] Linux, you'll have to somehow find the IP of each device to be
able to ssh (you won't be using telnet or FTP over wireless, will you?
;-).


> Can anyone tell me whether I can expect my 4 pc network to work ok
> without a base station?

It will, *if* you set all the devices to 'ad hoc' mode.  If you set them
to 'infrastructure' mode (or whatever the exact term is, used on your
device), they will search for a special 'access point' (=> base station)
wireless device, which will offer the gateway out of the wireless network
and onto the backend wired network.


> Can anyone recommend the cheapest most plug 'n play pcmcia & usb devices
> to purchase?

Nope.  The stuff I like the best is the various rebranded Lucent cards: I
have an Apple AirPort card in my Mac, an AirPort (802.11b - 11Mbps) base
station and a Toshiba laptop with Toshiba mini-PCI wireless card which
worked under Linux fine.  All these are Lucent devices underneath.

The Lucent stuff isn't particularly cheap, but I've yet to have a problem
with it (c.f. some other makes).

A D-Link card I bought for someone worked fine but needed a lot of messing
around with drivers first.

All that said, I've seen stuff from various manufacturers all just working
OK and people using them who are not highly computer-literate (including
these autoconfiguring NATing wireless gateways for home).  People I know
are just using those without trouble - no messing around with iptables,
like wot I do [I wonder why I bother!]


> Any other gotchas I should look out for?

Probably not, but just consider whether you should be going for 802.11g
(54Mbps) rather than plain 'b'.  I'm quite happy with 'b' and the extra
speed wouldn't really be worth it for me - the convenience of wireless is
enough and, if I need the bandwidth, I prefer the 'genuine' ~100Mbps of
wired to the 'if you're lucky' 11Mbps (typically around 5/6Mbps) on
wireless and there are lot less questions with 'b', although 'g' is
supposedly all backwards compatible.

One thing to bear in mind is how insecure wireless is.  WEP isn't worth
much (it also slows down your connection to about 75% of without it, in my
tests) so expect to need to use SSH and SFTP (or something else encrypted)
if you're going to be logging in over it.  If you need to read email with
POP/IMAP [for example] and can't use SSL on the actually connection, use
SSH to tunnel a port-forwarded connection (or VPN or somesuch).

If you end up with a base station, I would recommend (to stop authorised
people connecting):

  - disabling SSID advertisement (make it a 'closed' network)
  - using WEP (128-bit), although it's use is debatably pointless
  - limiting the MAC addresses which can connect

These are all easily circumventable security layers, but it does stop
people accidently joinging your network (especially the first one, if
nothing else).

Aside from all that, wireless is great.  Once you've had it, you won't
want to lose it.

  - Bob


-- 
 Bob Franklin <r.c.franklin at reading.ac.uk>          +44 (0)118 378 6630
 Systems and Communications, IT Services, The University of Reading, UK